NASPE POLICY STATEMENT
Catheter Ablation for Cardiac Arrhythmias, Personnel, and Facilities MELVIN M. SCHEINMAN, Chairman For the NASPE Ad Hoc Committee on Catheter Ablation*
Introduction Catheter ablation for control of cardiac arrhythmias was first introduced approximately 10 years ago. Since then these procedures have largely supplanted the need for expensive and potentially more dangerous open heart surgical procedures. Catheter ablative procedures constitute a major, dramatic advance in patient care and as such have become the most widely practiced nonpharmacological technique for management of patients with supraventricular tachycardia. The current CPT code 93650 “Intracardiac Catheter Ablation of Arrhythmogenic Focus or Tracts With or Without Temporary Pacemaker Placement” does not compensate for ablative procedures. This article was approved by the North American Society of Pacing and Electrophysiology Board of Trustees on May 27,1991 and was presented to the Health Care Finance Administration in order to document the need for adequate reimbursement of catheter ablative procedures.
A. Definition of Terms and Methods of Procedure Ablation refers to the intentional destruction of arrhythmogenic myocardial tissue, accessory
* NASPE Ad Hoc Committee on Catheter Ablation members: Masood Akhtar, Leonard Dreifus, G. Thomas Evans, Jr., Paul Gillette, S.K. Stephen Huang, Warren Jackman, Jonathan J. Langberg, James Maloney, Fred Morady, Jeremy Ruskin, Sanjeev Saksena, A1 Waldo, and Douglas Zipes. Address for reprints: Melvin Scheinman, M.D., Room 312, Moffitt Hospital, Box 0214, University of California, San Francisco, CA 94143. Fax: (415) 476-6260. Received February 5, 1992; accepted February 6, 1992.
PACE, Vol. 15
atrioventricular connections, or parts of the specialized conduction system in order to cure or control cardiac rhythm disturbances. Ablative procedures may be performed by using surgical or electrode catheter methods, or by delivery of caustic substances to the target area. Catheter ablative procedures involve delivery of either direct current shocks or radiofrequency pulses via standard electrode catheters. The energy sources are delivered via either a direct current defibrillator or radiofrequency unit. The methods of procedure vary depending on the type of arrhythmia treated and include: complete ablation of the atrioventricular junction, modification of the atrioventricular node, and ablation of accessory atrioventricular pathways. Complete ablation of the atrioventricular junction involves insertion of an electrode catheter in the region of the atrioventricular junction with delivery of direct current or radiofrequency current in order to interrupt impulse transmission from atrium to ventricle. Modification of the atrioventricular node is used to eliminate atrioventricular nodal reentrant tachycardia while leaving atrioventricular nodal conduction intact. For patients with accessory atrioventricular connections, the catheter is placed in close approximation to the pathway in order to desiccate this tissue by delivery of radiofrequency energy pulses.
B. Safety and Efficacy of Catheter Ablative Procedures Catheter ablation was first used clinically in 1981 and initially involved use of high energy di-
rect current shocks for destruction of the atrioventricular junction in patients with drug refractory supraventricular arrhythmias. This particular ab-
May 1992
715
SCHEINMAN, ET AL.
lative procedure has been used in more than 1,000 patients worldwide and the early results have been well summarized in a recent monograph.' The largest single report of high energy direct current ablation comes from the Percutaneous Catheter Mapping and Ablation Registry (PCMAR), which has accumulated data for 552 patients fol18 months.' These palowed for a mean of 23 tients were intolerant to or failed to respond to a mean of 3 . 5 antiarrhythmic medications. Sixtyfour percent of patients had atrial fibrillation or flutter, had atrioventricular nodal reentry tachycardia, and the remainder had a variety of supraventricular arrhythmias.
*
Efficacy and Safety of Direct Current Shocks for Atrioventricular Junctional Ablation Sixty-four percent of patients who achieved third-degree atrioventricular block remain without symptoms or need for antiarrhythmic therapy. However, chronic cardiac pacing is required. Eight percent of patients had return of conduction but with arrhythmia control without a requirement for antiarrhythmic therapy. Twelve percent of patients had a return of conduction without symptoms but required an antiarrhythmic drug for arrhythmia control. Sixteen percent of patients were considered to have failed ablation therapy. Acute major complications of high energy direct current ablation are rare but include induction of ventricular arrhythmias, myocardial perforation, or venous thrombosis. The most serious in-
hospital complication is polymorphous ventricular tachycardia, and occurs in approximately 4% of patients. The most serious reported complication is a 1.5% incidence of sudden cardiac death that may occur from 3 days to 6 months after ablation. Data describing the course of 49 patients followed for a mean of 4 1 f 20 months have been de~cribed.~ At the time that this report was being prepared, little published information was available regarding the safety and efficacy of catheter ablative procedures using radiofrequency energy. The Committee decided to pool the available data from five of the most active U.S. centers as of October 1991 (nonpeer reviewed) performing radiofrequency ablation procedures. Data from these centers are summarized in Tables I, 11, and 111. The incidence of the type of ablative procedure varies among the institutions as well as the incidence of procedures involving pediatric patients (< 16 years) (0%-12%). It should be emphasized that patient follow-up time was not provided and that in most instances was < 2.5 years. Results of Radiofrequency Ablation of the Atrioventricular Junction The reported efficacy of radiofrequency ablation of the atrioventricular junction varies from 70%-95%. Only a limited number of published reports using radiofrequency ablation have been p u b l i ~ h e d .Pooled ~ . ~ data submitted from five centers in the United States as of October 1991, are
Table I. Atrioventricular Junction Ablation (260 patients) Center A
Center B
Center C
Center D
Patients 30 Success 99% Complications EMD and death in patient with severe myocardial disease (1 patient)
Patients 95 Success 99% Complications None
Patients 14 Success 86% Complications Myocardial infarction (1 patient) Sudden death (1 patient)
Patients 66 Success 98% Complications Tamponade (1 patient) Groin hernatoma (1 patient) Pericarditis (1 Datient)
EMD
716
=
Center
E
Patients 55 Success 95% Complications Mild chest pain (4 patients)
electromechanical dissociation.
May 1992
PACE, Vol. 15
NASPE POLICY STATEMENT
Table It. Accessory Atrioventricular Connection Ablation (787 patients)
Center A
Center B
Patients 247 Patients 260 Success 99% Success 95% Complications Complications Complete AVB Left circumflex occlusion (1 patient) Tamponade (1 patient) (1 patient) Left coronary artery Pericarditis spasm (1 patient) (1 patient) TIA I-week Groin hematoma postablation (1 patient) (1 patient) Femoral artery Large pelvic pseudoaneurysm hematoma (1 patient) (1 patient) Right atrial clot Femoral artery (2 patients) pseudoaneurysm Left at rial (1 patient) hematoma Aortic valve perforation, mild Al (1 patient) (1 patient) Complete AVB, permanent pacemaker (1 Datient) Al = aortic insufficiency; A V B
=
Center C
Center D
Center E
Patients 98 Success 88% Complications Damage to a congenitally fenestrated aortic valve (1 patient) Pulmonary embolus (1 patient) AVB (1 patient) Pneumothorax (1 patient) Groin hematoma (1 patient)
Patients 126 Success 88% Complications Tamponade (2 patients) Microembolus to foot (1 patient) Coronary artery spasm (1 patient)
Patients 56 Success 95% Complications Mildmoderate chest pain (6 patients)
atrioventricular block; TIA
=
transient ischemic attack.
Table Ill. Atrioventricular Modification for Atrioventricular Node Reentry Tachycardia
Center A
Center B
Center C
Center D
Center E
Patients 57 Success 99% Complications AVB (1 patient) Pulmonary embolus (1 patient)
Patients 130 Success 85% Complications Complete AVB (7 patients)
Patients 41 Success 85% Complications AVB (4 patients)
Patients 50 Success 05% Complications Complete AVB (6 patients) Leg deep vein thrombosis (1 patient) Pericardial effusion (asympt o mat ic) (1 Patient)
Patients 37 Success 97% Complications None
AVB
=
atrioventricular block.
PACE, Vol. 15
May 1992
71 7
SCHEINMAN, ET AL.
included in Table I. Data compiled for 260 consecutive patients who underwent radiofrequency ablation of the atrioventricular junction were supplied to the Committee from five centers in the U.S. The procedure was successful as defined by induction of complete atrioventricular block in 86%-99% of patients. Serious complications include late sudden death in one, electromechanical dissociation (EMD) and death, and acute myocardial infarction within 1 week after the procedure. In summary, the radiofrequency technique appears safer and is as effective as direct current shock. There is only one reported sudden cardiac death following radiofrequency ablation," and use of radiofrequency energy obviates the need for general anesthesia during the ablative procedure. Results of Catheter Ablation of Accessory Atrioventricular Connections The worldwide experience using direct current ablation or destruction of accessory atrioventricular connections has been summarized.' The largest reported series using direct current ablation was reported by Warin et al.,7 who reported a 96% success rate in 246 consecutive patients. Significant complications included a 2% incidence of cardiac tamponade, a 2% incidence of sudden death, and four patients required permanent cardiac pacemakers. Radiofrequency energy has largely supplanted use of high energy direct current shocks for ablation of accessory atrioventricular connections. The pooled results of using radiofrequency energy for catheter ablation of accessory connections as of October 1991 are summarized in Table 11. Data for 787 patients who underwent attempted radiofrequency ablation of accessory atrioventricular connections are detailed. The reported success rate defined as ablation of pathway function and tachycardia control without medications ranged from 88%-99Y0. Significant acute complications included coronary arterial spasm in three with myocardial infarction in one. There were two instances of aortic valve damage and three patients had cardiac tamponade requiring pericardiocentesis. Three instances of atrioventricular block were reported in attempted ablation of septa1 accessory pathways. Clots in either the right or left atrium appear to be infrequent, and only one systemic and
718
one pulmonary embolus has been reported. The incidence of emboli is low whether postprocedure anticoagulants are used or not used. No procedure related deaths or sudden deaths postprocedure have been reported. Results of Atrioventricular Nodal Modification for Patients with Atrioventricular Nodal Reentry Initial reports described the use of high energy direct current discharges for patients with atrioventricular nodal r e e n t r ~ . Efficacy ~.~ in terms of tachycardia cure is approximately 85% but the procedure is associated with a 5%-10% incidence of atrioventricular block. Selective ablation of the slow atrioventricular nodal pathway may reduce the risk of complete atrioventricular block. More recently, other groups have described using radiofrequency energy for atrioventricular nodal modification.'Oal* The composite experience for five reporting centers as of October 1991 is detailed in Table 111. Data from 315 consecutive patients undergoing attempted radiofrequency modification of the atrioventricular nodal region were reported. Successful modification was defined as complete ablation or modification of either fast or slow atrioventricular nodal conduction resulting in tachycardia cure without producing third-degree atrioventricular block. The procedure was found to be successful in 85Y0-99Y0 of patients. The chief complication reported was induction of complete atrioventricular block, which occurred almost exclusively for those patients who had attempted fast pathway ablation.
C. Indication for Use Catheter ablation of the atrioventricular junction is currently considered the procedure of choice for patients with drug refractory arrhythmias arising from atrial tissue. Similarly, catheter ablation of the accessory atrioventricular connection is the procedure of choice for patients with drug refractory accessory pathway mediated tachycardias. The remarkable efficacy and safety of the latter procedure allows for extension of its use for patients with symptomatic tachycardias [involving an accessory connection) who refuse lifelong dependence on drug therapy. Catheter modifica-
May 1992
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NASPE POLICY STATEMENT
since: (1)it does not eliminate the arrhythmia and tion of the atrioventricular node is the procedure patients remain symptomatic from their arrhythof choice for patients with drug refractory atriomias or during pacing induced termination; (2) apventricular nodal reentrant tachycardia and may plication of antitachycardia pacing puts the pabe used to avoid lifelong dependence on drug thertient at risk for induction of atrial fibrillation or apy for symptomatic patients with atrioventricular atrial flutter, which may result in life-threatening nodal reentry. This procedure is believed preferaarrhythmias for patients with Wolff-Parkinsonble to surgery in terms of expense, pain, and other White syndrome. discomfort. These recommendations are supported by a recent “state-of-the-art” statement from the ECG E. Considerations of Cost and Electrophysiology Committee of the American Heart Association’’ peer reviewed l i t e r a t ~ r e , ’ ~ . ~ ~ Catheter ablation of most supraventricular tachycardias involves a 1-2-day hospital stay in a and by the major textbooks of ~ardiology.l’-~~ unit with ECG monitoring. Initial diagnostic and follow-up studies to document successful ablation D. Comparison with Other are also required and may be performed at a referTechniques or Procedures ring institution. The total cost of the ablative procedure itself, including the physician fee, ranges Alternative therapy includes use of drugs for from $12,000-$18,000. This is approximately one tachycardia control, antitachycardia pacing, and third the total cost of surgical treatment.” direct cardiac surgical ablation. Heretofore, carThe length of the ablative procedure includdiac surgery has been considered the treatment of ing electrophysiological assessment averages 3-6 choice for patients with drug refractory supraven12 hours. Considering the hours but could exceed Cardiac surgery is effectricular arrhythmias. training, expertise, and time required for catheter tive but requires an open heart procedure, a hospiablation, the physician compensation (typically tal stay of 5-8 days and prolonged convalescence < 50% of the currently accepted $5,000-$8,000) is until complete recovery is achieved. Catheter ablarate for comparable procedures. An example tion is preferable to surgery in patients with drug would be coronary balloon angioplasty. It should refractory arrhythmias arising from atrial tissue be further emphasized that the catheter ablative because it is associated with a lower immediate procedure has a better than 90% rate of permanent morbidity and mortality and costs much less than cure. surgery. Catheter ablation for patients with accessory pathway mediated tachycardia or atrioventricular nodal reentrant arrhythmia is curative and F. Unanswered Questions and thus obviates lifelong need for drug therapy. The Future Research catheter approach involves a short hospital stay Future research will involve development of (1-3 days) after which the patient resumes normal catheters with better steerability to allow for easier activities. access to sites of accessory atrioventricular conDrug therapy for patients with resistant arnections. In addition, future research will unrhythmias who require multiple drugs may be exdoubtedly focus on additional energy sources and pensive, especially when factored over the ablations of other arrhythmias in order to improve projected life of younger patients and are often asthe safety and efficacy of these procedures. The sociated with adverse effects. Many of the availpotential long-term risks of radiation exposure able drugs are not suitable for pregnant women sometimes required for lengthy procedures need because of unknown (or known) potential for terato be more fully assessed. In some institutions, abtogenic effects. Drugs often require meticulous atlative procedures are being used for selected patention to proper timing and dosage since missing tients with ventricular tachycardia. or altering a single dose may place the patient at There is a need for long-term follow-up surrisk for recurrent arrhythmias and many patients veillance of patients undergoing catheter ablation are averse to lifelong dependence on drug therapy. in terms of long-term efficacy and safety. Antitachycardia pacing is seldom used today
PACE, Vol. 15
May 1992
719
SCHEINMAN, ET AL.
G. Personnel Physicians The minimum requirements for physician performance of catheter ablation procedures include completion of training for Electrophysiology Board eligibility. The individual should have been the primary operator for a minimum of 30 catheter ablation procedures, including at least 15 accessory atrioventricular connection ablations. It was felt desirable that two physicians be involved in complex catheter ablation procedures, particularly those involving ablation of accessory pathways or ventricular tachycardia. The second physician need not be a trained electrophysiologist but should be adept in catheter manipulation and treatment of cardiac emergencies. A cardiology or electrophysiology postdoctoral fellow could fill this role. To assure good quality and continued competence, it was felt that the physician should perform at least 20 ablative procedures per year with anticipated success rates of at least 80% for complete atrioventricular junctional ablation, atrioventricular node modification for atrioventricular node reentry, and accessory pathway ablation. The success rate for ventricular tachycardia should be at least 30%. Laboratory Personnel Laboratory personnel should include two nurses (or technicians). One nurse (or physician assistant) is required to administer sedation and carefully monitor vital signs throughout the procedure. The committee felt that ablation procedures should only be performed in centers with ready availability of cardiac surgical support and percutaneous translurninal coronary angioplasty (PTCA)teams. It was not felt that a cardiac surgeon or anesthesiologist need be present, but they should be available for emergencies. It is not necessary to perform these procedures in the operating room. Facilities and Equipment Ablative procedures should be performed in a facility set up for invasive electrophysiological studies. The minimum standards for x-ray equipment should constitute a rotatable C arm or table
720
with good quality x-ray image. A video recording system for the fluoroscopic images is recommended. Biplane x-ray equipment is felt to be desirable but not absolutely necessary. State-of-theart roentgenographic equipment is favored in order to minimize radiation exposure and the radiation times should be carefully logged for all procedures. It was felt that the laboratory should establish guidelines for total radiation exposure for these procedures (a recent study” showed that the highest exposure of radiation was to the posterior 9th thoracic vertebral body, which received an average of approximately 19 rads. Radiation experts feel that this degree of exposure would be associated with a lifetime excess risk of fatal malignancy of approximately 1in 1,000 of dying from a maIignancy during their lifetime. It should be noted that the background risk of dying from a malignancy is 200 per 1,000 for a 35-year-old individual. This level of risk was felt to be lower than the risk of alternative medical or surgical treatment). The laboratory should be equipped to care for patients with acute coronary complications (i.e., thrombus, spasm, cardiac tamponade, coronary dissection). In addition, facilities for temporary and permanent pacemaker insertion should be available. It is recommended that the devices used for such ablation procedures be utilized in a manner conforming to hospital, local, and national regulations governing their application.
H. Recommendations 1. Catheter ablation of the atrioventricular junction is recommended as the procedure of choice for patients with drug refractory symptomatic atrial arrhythmias, when complete atrioventricular block is the therapy of choice. 2. Catheter ablation of accessory pathway(s) is the treatment of choice for patients with drug intolerant or drug resistant arrhythmias mediated by accessory pathways. 3. Catheter modification of the atrioventricular junction is the treatment of choice for patients with drug intolerant or drug resistant atrioventricular nodal reentrant tachycardia. 4. These procedures are also recommended as alternative therapy for patients with symptomatic arrhythmias who desire avoidance of lifelong drug therapy.
May 1992
PACE, Vol. 15
NASPE POLICY STATEMENT
References 1. Newman D, Evans GT Jr, Scheinman MM. Catheter
2.
3.
4.
5.
6.
7.
8.
9.
10.
ablation of cardiac arrhythmias. In RA O’Rouke (ed.): Current Problems in Cardiology. St. Louis, MO, Year Book Medical Publishers, 1989, 14(4); pp. 123-164. Evans GT Jr, Scheinman MM, the Executive Committee of the Registry. The Percutaneous Cardiac Mapping and Ablation Registry: Final summary of results. PACE 1988; 11(1):1621-1626. Rosenqvist M, Lee MA, Moulinier L, et al. Longterm follow-up of patients after transcatheter direct current ablation of the atrioventricular junction. J Am Coll Cardiol 1990; 16:1467-1474. Langberg JJ, Chin MC, Rosenqvist M, et al. Catheter ablation of the atrioventricular junction with radiofrequency energy. Circulation 1989; 80:1527-1535. Jackman WM, Wang X, Friday KJ, et al. Catheter ablation of atrioventricular junction using radiofrequency current in 1 7 patients: Comparison of standard and large-tip catheter electrodes. Circulation 1991; 83:1562-1576. Evans GT, Scheinman MM, Bardy G, et al. Predictors of in-hospital mortality after direct current catheter ablation of the atrioventricular junction: Results of a prospective, international, multicenter study. Circulation 1991; 84:1924-1937. Warin J-F. Catheter ablation of accessory pathways: Technique and results in 248 patients. PACE 1990; 13:1609-1614. Haissaguerre M, Warin J-F, Lematayer P, et al. Closed-chest ablation of retrograde conduction in patients with atrioventricular nodal reentrant tachycardia. N Engl J Med 1989; 320:426-433. Epstein LM, Scheinman MM, Langberg JJ, et al. Percutaneous catheter modification of the atrioventricular node: A potential cure for atrioventricular nodal tachycardia. Circulation 1989; 80:757-768. Lee MA, Morady F, Kadish A, et al. Catheter modification of the atrioventricular junction with radiofrequency energy for control of atrioventricular nodal reentry tachycardia. Circulation 1991; 83:827-835.
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11. Roman CA, Wang X, Friday KJ, et al. Catheter tech-
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
May 1992
nique for selective ablation of slow pathway in AV nodal reentrant tachycardia. (abstract) PACE 1990; 13:498. Scheinman MM, Laks MM, DiMarco J, et al. Current role of catheter ablative procedures in patients with cardiac arrhythmias. Circulation 1991; 83:2146-2153. Calkins H, Sousa J, El-Atassi R, et al. Diagnosis and cure of the Wolff-Parkinson-White syndrome or paroxysmal supraventricular tachycardias during a single electrophysiologic test. N Engl J Med 1991; 324:1612-1618. Jackman WM, Xunzhang W, Friday KJ. Catheter ablation of accessory atrioventricular pathways (Wolff-Parkinson-White syndrome) by radiofrequency current. N Engl J Med 1991; 324:1605-1611. Braunwald E. Heart Disease Update. A Textbook of Cardiovascular Medicine, Third Edition. Philadelphia, PA, W.B. Saunders, p. 334-342. Scheinman MM. Treatment of cardiac arrhythmias with catheter ablative techniques. In JW Hurst, RC Schlant (eds.):The Heart. New York, NY, McGrawHill (In press). Scheinman MM. Catheter ablation for cardiac arrhythmias. In WW Parmley, K Chatterjee (eds.): Cardiology, Volume 1. Philadelphia, PA, J.B. Lippincott, pp. 1-11. Cox JL, Gallagher JJ, Cain ME. Experience with 118 consecutive patients undergoing operation for the Wolff-Parkinson-White syndrome. J Thorac Cardiovasc Surg 1985; 90:490-501. Guiraudon GM, Klein GJ, Sharma AD, et al. Closed heart technique for Wolff-Parkinson-White syndrome: Further experience and potential limitations. Ann Thorac Surg 1986; 42:651-657. DeBuitleir JD, Sousa J, Bolling SF, et al. Reduction in medical care cost associated with radiofrequency catheter ablation of accessory pathways. Am J Cardiol 1991; 68:1656-1661. Calkins H, Nicklason L, Sousa J, et al. Radiation exposure during radiofrequency ablation of accessory atrioventricular connections. Circulation 1991; 84:2376-2382.
721
Catheter Ablation for Cardiac Arrhythmias, Personnel, and Facilities MELVIN M. SCHEINMAN, Chairman For the NASPE Ad Hoc Committee on Catheter Ablation*
Introduction Catheter ablation for control of cardiac arrhythmias was first introduced approximately 10 years ago. Since then these procedures have largely supplanted the need for expensive and potentially more dangerous open heart surgical procedures. Catheter ablative procedures constitute a major, dramatic advance in patient care and as such have become the most widely practiced nonpharmacological technique for management of patients with supraventricular tachycardia. The current CPT code 93650 “Intracardiac Catheter Ablation of Arrhythmogenic Focus or Tracts With or Without Temporary Pacemaker Placement” does not compensate for ablative procedures. This article was approved by the North American Society of Pacing and Electrophysiology Board of Trustees on May 27,1991 and was presented to the Health Care Finance Administration in order to document the need for adequate reimbursement of catheter ablative procedures.
A. Definition of Terms and Methods of Procedure Ablation refers to the intentional destruction of arrhythmogenic myocardial tissue, accessory
* NASPE Ad Hoc Committee on Catheter Ablation members: Masood Akhtar, Leonard Dreifus, G. Thomas Evans, Jr., Paul Gillette, S.K. Stephen Huang, Warren Jackman, Jonathan J. Langberg, James Maloney, Fred Morady, Jeremy Ruskin, Sanjeev Saksena, A1 Waldo, and Douglas Zipes. Address for reprints: Melvin Scheinman, M.D., Room 312, Moffitt Hospital, Box 0214, University of California, San Francisco, CA 94143. Fax: (415) 476-6260. Received February 5, 1992; accepted February 6, 1992.
PACE, Vol. 15
atrioventricular connections, or parts of the specialized conduction system in order to cure or control cardiac rhythm disturbances. Ablative procedures may be performed by using surgical or electrode catheter methods, or by delivery of caustic substances to the target area. Catheter ablative procedures involve delivery of either direct current shocks or radiofrequency pulses via standard electrode catheters. The energy sources are delivered via either a direct current defibrillator or radiofrequency unit. The methods of procedure vary depending on the type of arrhythmia treated and include: complete ablation of the atrioventricular junction, modification of the atrioventricular node, and ablation of accessory atrioventricular pathways. Complete ablation of the atrioventricular junction involves insertion of an electrode catheter in the region of the atrioventricular junction with delivery of direct current or radiofrequency current in order to interrupt impulse transmission from atrium to ventricle. Modification of the atrioventricular node is used to eliminate atrioventricular nodal reentrant tachycardia while leaving atrioventricular nodal conduction intact. For patients with accessory atrioventricular connections, the catheter is placed in close approximation to the pathway in order to desiccate this tissue by delivery of radiofrequency energy pulses.
B. Safety and Efficacy of Catheter Ablative Procedures Catheter ablation was first used clinically in 1981 and initially involved use of high energy di-
rect current shocks for destruction of the atrioventricular junction in patients with drug refractory supraventricular arrhythmias. This particular ab-
May 1992
715
SCHEINMAN, ET AL.
lative procedure has been used in more than 1,000 patients worldwide and the early results have been well summarized in a recent monograph.' The largest single report of high energy direct current ablation comes from the Percutaneous Catheter Mapping and Ablation Registry (PCMAR), which has accumulated data for 552 patients fol18 months.' These palowed for a mean of 23 tients were intolerant to or failed to respond to a mean of 3 . 5 antiarrhythmic medications. Sixtyfour percent of patients had atrial fibrillation or flutter, had atrioventricular nodal reentry tachycardia, and the remainder had a variety of supraventricular arrhythmias.
*
Efficacy and Safety of Direct Current Shocks for Atrioventricular Junctional Ablation Sixty-four percent of patients who achieved third-degree atrioventricular block remain without symptoms or need for antiarrhythmic therapy. However, chronic cardiac pacing is required. Eight percent of patients had return of conduction but with arrhythmia control without a requirement for antiarrhythmic therapy. Twelve percent of patients had a return of conduction without symptoms but required an antiarrhythmic drug for arrhythmia control. Sixteen percent of patients were considered to have failed ablation therapy. Acute major complications of high energy direct current ablation are rare but include induction of ventricular arrhythmias, myocardial perforation, or venous thrombosis. The most serious in-
hospital complication is polymorphous ventricular tachycardia, and occurs in approximately 4% of patients. The most serious reported complication is a 1.5% incidence of sudden cardiac death that may occur from 3 days to 6 months after ablation. Data describing the course of 49 patients followed for a mean of 4 1 f 20 months have been de~cribed.~ At the time that this report was being prepared, little published information was available regarding the safety and efficacy of catheter ablative procedures using radiofrequency energy. The Committee decided to pool the available data from five of the most active U.S. centers as of October 1991 (nonpeer reviewed) performing radiofrequency ablation procedures. Data from these centers are summarized in Tables I, 11, and 111. The incidence of the type of ablative procedure varies among the institutions as well as the incidence of procedures involving pediatric patients (< 16 years) (0%-12%). It should be emphasized that patient follow-up time was not provided and that in most instances was < 2.5 years. Results of Radiofrequency Ablation of the Atrioventricular Junction The reported efficacy of radiofrequency ablation of the atrioventricular junction varies from 70%-95%. Only a limited number of published reports using radiofrequency ablation have been p u b l i ~ h e d .Pooled ~ . ~ data submitted from five centers in the United States as of October 1991, are
Table I. Atrioventricular Junction Ablation (260 patients) Center A
Center B
Center C
Center D
Patients 30 Success 99% Complications EMD and death in patient with severe myocardial disease (1 patient)
Patients 95 Success 99% Complications None
Patients 14 Success 86% Complications Myocardial infarction (1 patient) Sudden death (1 patient)
Patients 66 Success 98% Complications Tamponade (1 patient) Groin hernatoma (1 patient) Pericarditis (1 Datient)
EMD
716
=
Center
E
Patients 55 Success 95% Complications Mild chest pain (4 patients)
electromechanical dissociation.
May 1992
PACE, Vol. 15
NASPE POLICY STATEMENT
Table It. Accessory Atrioventricular Connection Ablation (787 patients)
Center A
Center B
Patients 247 Patients 260 Success 99% Success 95% Complications Complications Complete AVB Left circumflex occlusion (1 patient) Tamponade (1 patient) (1 patient) Left coronary artery Pericarditis spasm (1 patient) (1 patient) TIA I-week Groin hematoma postablation (1 patient) (1 patient) Femoral artery Large pelvic pseudoaneurysm hematoma (1 patient) (1 patient) Right atrial clot Femoral artery (2 patients) pseudoaneurysm Left at rial (1 patient) hematoma Aortic valve perforation, mild Al (1 patient) (1 patient) Complete AVB, permanent pacemaker (1 Datient) Al = aortic insufficiency; A V B
=
Center C
Center D
Center E
Patients 98 Success 88% Complications Damage to a congenitally fenestrated aortic valve (1 patient) Pulmonary embolus (1 patient) AVB (1 patient) Pneumothorax (1 patient) Groin hematoma (1 patient)
Patients 126 Success 88% Complications Tamponade (2 patients) Microembolus to foot (1 patient) Coronary artery spasm (1 patient)
Patients 56 Success 95% Complications Mildmoderate chest pain (6 patients)
atrioventricular block; TIA
=
transient ischemic attack.
Table Ill. Atrioventricular Modification for Atrioventricular Node Reentry Tachycardia
Center A
Center B
Center C
Center D
Center E
Patients 57 Success 99% Complications AVB (1 patient) Pulmonary embolus (1 patient)
Patients 130 Success 85% Complications Complete AVB (7 patients)
Patients 41 Success 85% Complications AVB (4 patients)
Patients 50 Success 05% Complications Complete AVB (6 patients) Leg deep vein thrombosis (1 patient) Pericardial effusion (asympt o mat ic) (1 Patient)
Patients 37 Success 97% Complications None
AVB
=
atrioventricular block.
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May 1992
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included in Table I. Data compiled for 260 consecutive patients who underwent radiofrequency ablation of the atrioventricular junction were supplied to the Committee from five centers in the U.S. The procedure was successful as defined by induction of complete atrioventricular block in 86%-99% of patients. Serious complications include late sudden death in one, electromechanical dissociation (EMD) and death, and acute myocardial infarction within 1 week after the procedure. In summary, the radiofrequency technique appears safer and is as effective as direct current shock. There is only one reported sudden cardiac death following radiofrequency ablation," and use of radiofrequency energy obviates the need for general anesthesia during the ablative procedure. Results of Catheter Ablation of Accessory Atrioventricular Connections The worldwide experience using direct current ablation or destruction of accessory atrioventricular connections has been summarized.' The largest reported series using direct current ablation was reported by Warin et al.,7 who reported a 96% success rate in 246 consecutive patients. Significant complications included a 2% incidence of cardiac tamponade, a 2% incidence of sudden death, and four patients required permanent cardiac pacemakers. Radiofrequency energy has largely supplanted use of high energy direct current shocks for ablation of accessory atrioventricular connections. The pooled results of using radiofrequency energy for catheter ablation of accessory connections as of October 1991 are summarized in Table 11. Data for 787 patients who underwent attempted radiofrequency ablation of accessory atrioventricular connections are detailed. The reported success rate defined as ablation of pathway function and tachycardia control without medications ranged from 88%-99Y0. Significant acute complications included coronary arterial spasm in three with myocardial infarction in one. There were two instances of aortic valve damage and three patients had cardiac tamponade requiring pericardiocentesis. Three instances of atrioventricular block were reported in attempted ablation of septa1 accessory pathways. Clots in either the right or left atrium appear to be infrequent, and only one systemic and
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one pulmonary embolus has been reported. The incidence of emboli is low whether postprocedure anticoagulants are used or not used. No procedure related deaths or sudden deaths postprocedure have been reported. Results of Atrioventricular Nodal Modification for Patients with Atrioventricular Nodal Reentry Initial reports described the use of high energy direct current discharges for patients with atrioventricular nodal r e e n t r ~ . Efficacy ~.~ in terms of tachycardia cure is approximately 85% but the procedure is associated with a 5%-10% incidence of atrioventricular block. Selective ablation of the slow atrioventricular nodal pathway may reduce the risk of complete atrioventricular block. More recently, other groups have described using radiofrequency energy for atrioventricular nodal modification.'Oal* The composite experience for five reporting centers as of October 1991 is detailed in Table 111. Data from 315 consecutive patients undergoing attempted radiofrequency modification of the atrioventricular nodal region were reported. Successful modification was defined as complete ablation or modification of either fast or slow atrioventricular nodal conduction resulting in tachycardia cure without producing third-degree atrioventricular block. The procedure was found to be successful in 85Y0-99Y0 of patients. The chief complication reported was induction of complete atrioventricular block, which occurred almost exclusively for those patients who had attempted fast pathway ablation.
C. Indication for Use Catheter ablation of the atrioventricular junction is currently considered the procedure of choice for patients with drug refractory arrhythmias arising from atrial tissue. Similarly, catheter ablation of the accessory atrioventricular connection is the procedure of choice for patients with drug refractory accessory pathway mediated tachycardias. The remarkable efficacy and safety of the latter procedure allows for extension of its use for patients with symptomatic tachycardias [involving an accessory connection) who refuse lifelong dependence on drug therapy. Catheter modifica-
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since: (1)it does not eliminate the arrhythmia and tion of the atrioventricular node is the procedure patients remain symptomatic from their arrhythof choice for patients with drug refractory atriomias or during pacing induced termination; (2) apventricular nodal reentrant tachycardia and may plication of antitachycardia pacing puts the pabe used to avoid lifelong dependence on drug thertient at risk for induction of atrial fibrillation or apy for symptomatic patients with atrioventricular atrial flutter, which may result in life-threatening nodal reentry. This procedure is believed preferaarrhythmias for patients with Wolff-Parkinsonble to surgery in terms of expense, pain, and other White syndrome. discomfort. These recommendations are supported by a recent “state-of-the-art” statement from the ECG E. Considerations of Cost and Electrophysiology Committee of the American Heart Association’’ peer reviewed l i t e r a t ~ r e , ’ ~ . ~ ~ Catheter ablation of most supraventricular tachycardias involves a 1-2-day hospital stay in a and by the major textbooks of ~ardiology.l’-~~ unit with ECG monitoring. Initial diagnostic and follow-up studies to document successful ablation D. Comparison with Other are also required and may be performed at a referTechniques or Procedures ring institution. The total cost of the ablative procedure itself, including the physician fee, ranges Alternative therapy includes use of drugs for from $12,000-$18,000. This is approximately one tachycardia control, antitachycardia pacing, and third the total cost of surgical treatment.” direct cardiac surgical ablation. Heretofore, carThe length of the ablative procedure includdiac surgery has been considered the treatment of ing electrophysiological assessment averages 3-6 choice for patients with drug refractory supraven12 hours. Considering the hours but could exceed Cardiac surgery is effectricular arrhythmias. training, expertise, and time required for catheter tive but requires an open heart procedure, a hospiablation, the physician compensation (typically tal stay of 5-8 days and prolonged convalescence < 50% of the currently accepted $5,000-$8,000) is until complete recovery is achieved. Catheter ablarate for comparable procedures. An example tion is preferable to surgery in patients with drug would be coronary balloon angioplasty. It should refractory arrhythmias arising from atrial tissue be further emphasized that the catheter ablative because it is associated with a lower immediate procedure has a better than 90% rate of permanent morbidity and mortality and costs much less than cure. surgery. Catheter ablation for patients with accessory pathway mediated tachycardia or atrioventricular nodal reentrant arrhythmia is curative and F. Unanswered Questions and thus obviates lifelong need for drug therapy. The Future Research catheter approach involves a short hospital stay Future research will involve development of (1-3 days) after which the patient resumes normal catheters with better steerability to allow for easier activities. access to sites of accessory atrioventricular conDrug therapy for patients with resistant arnections. In addition, future research will unrhythmias who require multiple drugs may be exdoubtedly focus on additional energy sources and pensive, especially when factored over the ablations of other arrhythmias in order to improve projected life of younger patients and are often asthe safety and efficacy of these procedures. The sociated with adverse effects. Many of the availpotential long-term risks of radiation exposure able drugs are not suitable for pregnant women sometimes required for lengthy procedures need because of unknown (or known) potential for terato be more fully assessed. In some institutions, abtogenic effects. Drugs often require meticulous atlative procedures are being used for selected patention to proper timing and dosage since missing tients with ventricular tachycardia. or altering a single dose may place the patient at There is a need for long-term follow-up surrisk for recurrent arrhythmias and many patients veillance of patients undergoing catheter ablation are averse to lifelong dependence on drug therapy. in terms of long-term efficacy and safety. Antitachycardia pacing is seldom used today
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G. Personnel Physicians The minimum requirements for physician performance of catheter ablation procedures include completion of training for Electrophysiology Board eligibility. The individual should have been the primary operator for a minimum of 30 catheter ablation procedures, including at least 15 accessory atrioventricular connection ablations. It was felt desirable that two physicians be involved in complex catheter ablation procedures, particularly those involving ablation of accessory pathways or ventricular tachycardia. The second physician need not be a trained electrophysiologist but should be adept in catheter manipulation and treatment of cardiac emergencies. A cardiology or electrophysiology postdoctoral fellow could fill this role. To assure good quality and continued competence, it was felt that the physician should perform at least 20 ablative procedures per year with anticipated success rates of at least 80% for complete atrioventricular junctional ablation, atrioventricular node modification for atrioventricular node reentry, and accessory pathway ablation. The success rate for ventricular tachycardia should be at least 30%. Laboratory Personnel Laboratory personnel should include two nurses (or technicians). One nurse (or physician assistant) is required to administer sedation and carefully monitor vital signs throughout the procedure. The committee felt that ablation procedures should only be performed in centers with ready availability of cardiac surgical support and percutaneous translurninal coronary angioplasty (PTCA)teams. It was not felt that a cardiac surgeon or anesthesiologist need be present, but they should be available for emergencies. It is not necessary to perform these procedures in the operating room. Facilities and Equipment Ablative procedures should be performed in a facility set up for invasive electrophysiological studies. The minimum standards for x-ray equipment should constitute a rotatable C arm or table
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with good quality x-ray image. A video recording system for the fluoroscopic images is recommended. Biplane x-ray equipment is felt to be desirable but not absolutely necessary. State-of-theart roentgenographic equipment is favored in order to minimize radiation exposure and the radiation times should be carefully logged for all procedures. It was felt that the laboratory should establish guidelines for total radiation exposure for these procedures (a recent study” showed that the highest exposure of radiation was to the posterior 9th thoracic vertebral body, which received an average of approximately 19 rads. Radiation experts feel that this degree of exposure would be associated with a lifetime excess risk of fatal malignancy of approximately 1in 1,000 of dying from a maIignancy during their lifetime. It should be noted that the background risk of dying from a malignancy is 200 per 1,000 for a 35-year-old individual. This level of risk was felt to be lower than the risk of alternative medical or surgical treatment). The laboratory should be equipped to care for patients with acute coronary complications (i.e., thrombus, spasm, cardiac tamponade, coronary dissection). In addition, facilities for temporary and permanent pacemaker insertion should be available. It is recommended that the devices used for such ablation procedures be utilized in a manner conforming to hospital, local, and national regulations governing their application.
H. Recommendations 1. Catheter ablation of the atrioventricular junction is recommended as the procedure of choice for patients with drug refractory symptomatic atrial arrhythmias, when complete atrioventricular block is the therapy of choice. 2. Catheter ablation of accessory pathway(s) is the treatment of choice for patients with drug intolerant or drug resistant arrhythmias mediated by accessory pathways. 3. Catheter modification of the atrioventricular junction is the treatment of choice for patients with drug intolerant or drug resistant atrioventricular nodal reentrant tachycardia. 4. These procedures are also recommended as alternative therapy for patients with symptomatic arrhythmias who desire avoidance of lifelong drug therapy.
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