Eur .I Cardio-thorac
Surg (1991) 5:436-439
Surgery 0 Spring;-Verlag 1991
Recurrent atria1 arrhythmias following treatment for postoperative atria1 fibrillation after coronary bypass operations * R. W. Landymore and F. Howell Department
of Surgery, Division of Cardiovascular
Surgery, Dalhousie University,
Halifax, Nova Scotia, Canada
Abstract. Ambulatory Holter monitoring was performed in 58 patients during the early convalescence after myocardial revascularization in order to determine the incidence of recurrent atria1 arrhythmias following treatment for postoperative atria1fibrillation. Fifteen patients who had undergone coronary bypass and had not developed spontaneous atria1fibrillation following operation served as the controls (group 1). The remaining patients developed spontaneous symptomatic atria1 fibrillation after coronary bypass that required digitalization for rate control. Sixteen patients (group 2) continued taking digoxin for 8 weeks following operation, 13 patients (group 3) discontinued digoxin treatment 5 weeks following operation, and 14 patients (group 4) discontinued digoxin treatment 3 weeks following operation. Twenty-four-hour Holter monitoring indicated that asymptomatic atria1 fibrillation was common in the treatment groups after digitalization just before discharge from hospital. Atria1 fibrillation, however, rarely recurred following discharge from hospital and was never symptomatic. Our data indicate that patients who develop spontaneous postoperative atria1 fibrillation should be treated with digoxin for 3 weeks following operation and then drug therapy may be discontinued indefinitely. [Eur J Cardio-thorac Surg (1991) 5: 436-4391 Key words: Atria1 arrhythmia - Cardiac monitoring
Atria1 fibrillation occurs spontaneously in 8%-46% of patients following aortocoronary bypass operations [5, 161. The unheralded onset of supraventricular tachycardia is rarely associated with significant morbidity, although most patients require drug therapy and reinstitution of cardiac monitoring until the rapid ventricular response is controlled. The frequent occurrence of atria1 arrhythmias after cardiac operations has prompted numerous clinical trials that have investigated the efficacy of prophylactic antiarrhythmic drug therapy for the prevention of postoperative supraventricular arrhythmias [l-3, 5, 7, 8, 10, 11, 13, 14, 16, 181. However, there have been no clinical investigations that have specifically addressed the requirements for drug therapy following discharge from hospital. We felt that this was an important tissue to resolve, considering that many of our patients come from small, outlying communities where their convalescent care is provided solely by their personal physician. Frequently these patients may continue to take digoxin for protracted periods during their convalesReceived for publication: Accepted for publication: * Supported
March 4, 1991 May 2, 1991
by a New Brunswick Heart Foundation
Grant
cence. Thus, we designed this study, the aim of which was to determine the incidence of recurrent atria1 fibrillation after discharge in those patients who had required digitalization for symptomatic postoperative artrial fibrillation, in order to develop therapeutic guidelines for the pharmacological management of these patients during the early convalescence after coronary bypass. Patients and methods Fifty-eight patients undergoing elective myocardial revascularization gave informed consent to undergo 24-h Holter monitoring following operation. All patients undergoing coronary bypass operations were eligible to be entered into the study with the exception of patients requiring nonelective procedures and patients with a prior history of atria1 fibrillation. Cardiac anaesthesia was similar in all cases. Diazepam and papaveretum (Pantopon) were routinely used for preoperative sedation while anaesthesia was maintained with enflurane. Cardiopulmonary bypass was established with a single venous cannula while myocardial protection was provided with a combination of systemic cooling to 25 “C, multidose crystalloid cardioplegia (25 mEq K/l), and topical cooling. A combination of internal mammary artery and saphenous vein grafts were used for myocardial revascularization. Proximal and distal anastomoses were completed under a single aortic cross-clamp.
437
Patient subgroups The patients were prospectively randomized into two groups. Sixteen patients (group 2) were digitalized following the onset of atria1 fibrillation and instructed to continue taking digoxin for 8 weeks. Thirteen patients (group 3) were digitalized after developing spontaneous postoperative atria1 fibrillation and were instructed to discontinue digoxin 5 weeks after operation. Adequacy of digitalization was verified by measuring serum digoxin levels and by observing the therapeutic response to digitalization as evidenced by control of the tachycardia. The control group (group 1) was formed by 15 patients who had undergone coronary bypass and did not develop subsequent atria1 fibrillation. After the initial study was completed and the data were analysed, it became apparent that atria1 fibrillation was extremely uncommon following discharge from hospital in both treated groups. A further 14 patients (group 4) who had developed spontaneous atria1 fibrillation following coronary bypass were entered into the study to determine the effects of a shorter treatment period on the recurrence of postoperative atria1 arrhythmias. These patients were instructed to continue digoxin for only 3 weeks following operation.
Table 1. Patient profiles Age
Group 1
61
NYHA functional disability III
IV
IO
5
No. of grafts per pt.
Clamp time (min)
No. of pts. with intra-op AF
2.7
53
4
Group 2
61
12
4
2.5
51
3
Group 3
64
11
2
2.4
45
0
Group 4
59
10
4
3.0
59
3
NYHA = New York Heart Association;
Table 2. Holter monitoring l-3 No. of pts.
AF = atrial fibrillation
following coronary
Holter monitor before discharge
Holter monitoring Twenty-four-hour Holter monitoring was carried out just prior to discharge. All patients at this time were asymptomatic and had not complained of any paroxysms of atria1 tachycardia for at least 2-3 days prior to Holter monitoring. The control group and patients in groups 2 and 3 returned for further Holter monitoring at 3 and 6 weeks following operation, while the patients in group 4 underwent Holter monitoring prior to discharge and at 4 weeks following operation. Holter tapes were scanned manually for the presence of atria1 fibrillation and/or atria1 flutter. The electrophysiology laboratory reported the presence of atria1 tibrillation or atria1 flutter if more than four consecutive beats of the atria1 arrhythmia were present any time during the 24-h Holter monitoring.
Holter monitoring Results of the 24-h Holter monitoring are shown in Tables 2 and 3. Holter monitoring detected asymptomatic atria1 fibrillation in three patients in the control group just prior to discharge. Two patients experienced short runs of atria1 fibrillation, the longest run consisting of 18 beats. The third patient had a run of atria1 flutter for a duration of 191 beats. Patients in the treatment groups who had required digitalization for postoperative atria1 fibrillation did not have any recurrence of symptomatic atria1 arrhythmias after digitalization although 24-h
Atria1 fibrillation or flutter 3 wks after op.
6 wks after op.
Group 1
15
3 Patients 1. 1 Run 18 beats 2. 1 Run A-flutter 191 beats 3. 2 Runs longest 10 beats
Nil
Nil
Group 2
16
6 Patients 1. 1 Run 9 beats 2. 2 Runs longest 37 beats 3. 626 Runs longest 21 beats 4. 44 runs longest 520 beats 5. 2 Runs longest 9 beats 6. 53 Runs longest 519 beats
1 Patient 19 runs longest 512 beats
1 Patient 26 Runs longest 518 beats
Group 3
13
6 Patients 1. 593 Runs longest 21 beats 2. 650 Runs longest 212 beats 3. 1471 Runs longest 109 beats 4. Underlying rhythm mainly AF-A-flutter 5. Underlying rhythm mainly AF 6. Underlying rhythm mainly AF
Nil
Nil
Results
The patient profiles are displayed in Table 1. The four groups were similar with respect to age, functional disability, number of grafts and clamp time. Spontaneous intraoperative atria1 fibrillation occurred after unclamping of the aorta in a few patients in each group. The intra-operative atria1 arrhythmia was electrically cardioverted. Four patients in the control group and three patients in group 2 developed postpericardiotomy syndrome.
bypass in groups
’ Four consecutive beats were considered a run of atrial tibrillation
Holter monitoring detected runs of atria1 fibrillation in these groups. Holter monitoring detected atria1 fibrillation in six patients in group 2, six patients in group 3 and five patients in group 4. The number of runs of atria1 fibrillation and the duration of the longest run are given in tables. Although atria1 fibrillation was frequently detected during Holter monitoring, the ventricular rate was
438 Table 3. Holter monitoring
Group 4
following coronary bypass in group 4”
No. of pts.
Holter monitor before discharge
14
5 Patients 1. Underlying rhythm mainly AF
1. 2RunsofAF longest 16 beats
2. 63 Runs AF longest 41 beats
2. 1 Run AF 5 beats
3. 1 Run AF I beats
3. 1 Run AF $ beats
4. 53 Runs AF longest 56 beats
4. 5 Runs AF longest 22 beats
5. 1 Run AF 4 beats
5. 4 Runs atria1 longest 17 beats
Atria1 fibrillation or flutter 3 wks after operation
a Four consecutive beats were considered a run of atria1 fibrillation well-controlled which failed to generate any
explains
why
these
arrhythmias
symptomatology. Atria1 fibrillation was uncommon in the control group and in groups 2 and 3 three weeks following operation. There were no episodes of atria1 fibrillation in the control group or group 3, but Holter monitoring demonstrated asymptomatic atria1 fibrillation in one patient in group 2 taking digoxin. This patient had 19 runs of atria1 fibrillation, the longest run consisting of 512 beats. Group 4 had discontinued digoxin 3 weeks following operation and underwent Holter monitoring 1 week later. Five out of 14 patients had evidence of atria1 fibrillation and/or flutter; however, the runs of atria1 fibrillation were of short duration and were asymptomatic. Holter monitoring was repeated 6 weeks after operation in the control group and in groups 2 and 3. At this time group 2 was still taking digoxin while group 3 had discontinued the drug 5 weeks after operation and 1 week prior to ambulatory monitoring. There was no atria1 fibrillation recorded in the control group or group 3 at this time. However, asymptomatic atria1 fibrillation was demonstrated in one patient in group 2 taking digoxin. The Holter tape identified 26 runs of atria1 fibrillation, the longest run consisting of 518 beats. This patient had also showed Holter evidence of asymptomatic atria1 fibrillation at 3 weeks and was noted to have had postpericardiotomy syndrome following operation.
Discussion
Atria1 fibrillation occurs spontaneously in as many as one-third of patients undergoing aortocoronary bypass operations [5]. The actual incidence of clinical arrhythmias, however, is lower because many studies have included asymptomatic atria1 arrhythmias. Hammon et al. [5] reported a 46% incidence of atria1 fibrillation after coronary bypass but included arrhythmias that lasted less than 10 s. White and associates [19] indicated that supraventricular tachycardia occurred in 35% of patients but included tachycardias that lasted less than 10 s or for a duration of 10 beats. Similarly, Janssen et al. [7] re-
ported a 36% incidence of supraventricular tachycardia after coronary bypass but included arrhythmias that lasted less than 1 min. The incidence of symptomatic postoperative atria1 fibrillation, however, is considerably lower and lies within a range of 16%-30% [8,10,13,18]. The prophylactic use of drug therapy to prevent postoperative atria1 fibrillation after coronary bypass has received considerable attention but has met with conflicting results. Mills et al. [lo] and Csiscko et al. [l] have indicated that prophylactic digitalization reduces the incidence of postoperative supraventricular tachycardia while Tyras and associates [18] observed that prophylactic digitalization increased the number of postoperative supraventricular arrhythmias. Smith and colleagues [14] reported that low-dose verapamil treatment failed to reduce the incidence of postoperative atria1 arrhythmias. In contrast, Davidson et al. [3] demonstrated that verapamil reduced the incidence of supraventricular tachyarrhythmias but cautioned against the prophylactic use of verapamil because its administration had frequently precipitated hypotension. Numerous clinical trials have examined the effects of beta-blockers on the incidence of postoperative supraventricular tachycardia. A review of these studies indicates that the prophylactic use of propranolol, or more selective beta-blockers, will significantly reduce but not prevent postoperative atria1 fibrillation [2, 8, 11, 13, 161. The aetiology of atria1 fibrillation after coronary bypass is uncertain. Smith and colleagues [15], in an experimental study, suggested that atria1 arrhythmias were related to inadequate atria1 and atrioventricular nodal protection during cardioplegic arrest after they demonstrated that the atrium received far less cardioplegia then the myocardium. They also discovered that the atria1 temperature rose almost immediately following the infusion of cardioplegia and that the atrium was always warmer than the myocardium. Tchervenkov and associates [I 71have also indicated that postoperative supraventricular tachyarrhythmias may be a manifestation of inadequate atria1 protection by demonstrating an association between the duration of atria1 activity during cardioplegic arrest and the occurrence of postoperative atria1 fibrillation. Although inadequate atria1 protection may play a role in the development of postoperative supraventricular tachycardia, the aetiology is probably multifactorial rather than related to a single determinant factor, as atria1 arrhythmias have been reported not only after interminant aortic cross-clamping [1,9,18] but after the use of cardioplegia [5, 10, 171. Furthermore, clinical studies reported by Rolfman and Fieldman [12] and Dixon et al. [4] have shown that older age, clamp time, left atria1 enlargement and cardiomegaly are associated with postoperative supraventricular arrhythmias. Atria1 fibrillation frequently complicates the postoperative convalescence of our patients following coronary bypass operations, but it is rarely associated with significant morbidity. Electrocardiographic monitoring in the intensive care unit will often demonstrate the presence of multiple premature atria1 contractions just prior to the onset of this arrhythmia, which usually becomes manifest within the first 4 days following operation. Rate control
439
and bedside monitoring are indicated in almost all patients following the onset of rapid atria1 fibrillation. Intravenous digitalization usually controls the ventricular response in most patients, although intravenously administered propranolol and/or verapamil may be required initially to control the ventricular rate. Cardioversion is only occasionally necessary in the rare patient who develops haemodynamic compromise. Ambulatory Holter monitoring has demonstrated that some patients may develop asymptomatic atria1 fibrillation or flutter within the first few days following a coronary bypass operation. Twenty percent of our control group had Holter evidence of atria1 fibrillation after operation without being aware of the arrhythmia. Twenty-four-hour Holter monitoring of the treatment groups indicated that atria1 fibrillation frequently reoccurs after digitalization. Slightly less than one-half of the patients in the treatment groups had episodes of asymptomatic atria1 fibrillation after digitalization, but these patients were unaware of their arrhythmias because the rate of the supraventricular tachycardia had been adequately controlled by drug therapy. There were no symptomatic atria1 arrhythmias after discharge from hospital. Holter monitoring failed to detect any arrhythmias in the control group and group 3, while there was only one patient with Holter evidence of atria1 fibrillation in group 2. Even the patients in group 4 had no significant atria1 arrhythmias, after taking digoxin for only 3 weeks following the initial treatment of atria1 fibrillation. Ambulatory monitoring, therefore, has shown that postoperative atria1 fibrillation is a transient arrhythmia that rarely recurs after initial treatment and discharge from hospital.
Conclusion
Atria1 fibrillation is a common but extremely transient arrhythmia following coronary bypass operations. The arrhythmia requires digitalization for rate control but does not require prolonged drug therapy. It is our practise now to digitalize patients initially after onset of the arrhythmia and then only treat these patients for a period of 3 weeks. This treatment regimen has not resulted in recurrence of symptomatic atria1 arrhythmias in any of our patients after coronary bypass operations.
3.
4.
5.
6.
I.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18. Acknowledgement. We would like to thank C. E. Kinley, MD, FRCSC, D. A. Murphy, MD, FRCSC, and J. Wood, MD, FRCSC, for allowing us to investigate some of their patients. 19.
acebutolol after coronary bypass grafting. Am J Cardioi 58: 933-936 Davison R, Hartz R, Kaplan K, Parker M, Feiereisel P, Michaelis L (1985) Prophylaxis of supraventricular tachyarrhythmia after coronary bypass surgery with oral verapamil: a randomized, double-blind trial. Ann Thorac Surg 39: 336-339 Dixon F, Genton E, Vacek J, Moore C, Landry J (1986) Factors predisposing to supraventricular tachyarrhythmias after coronary artery bypass grafting. Am J Cardiol 58:476-478 Hammon JW, Wood A, Prager R, Wood M, Muirhead J, Bender H (1984) Perioperative beta blockade with propranolol: reduction in myocardial oxygen demands and incidence of atria1 and ventricular arrhythmias. Ann Thorac Surg 38: 363 -367 Ivey M, Ivey T, Bailey W, Williams D, Hessel E, Miller D (1983) Influence of propranolol on supraventricular tachycardia early after coronary artery revascularization. J Thorac Cardiovasc Surg 85: 214-218 Janssen J, Loomans L, Harink J, Taams M, Brunninkhuis L, van der Starre P, Kootstra G (1986) Prevention and treatment of supraventricular tachycardia shortly after coronary artery bypass grafting: a randomized open trial. Angiology 37: 601-608 Matangi M, Neutze J, Graham K, Hill D, Kerr A, BarrettBoyes B (1985) Arrhythmia prophylaxis after aorta-coronary bypass. J Thorac Cardiovasc Surg 89: 439-443 Michelson E, Morganroth J, MacVaugh H (1979) Postoperative arrhythmias after coronary artery and cardiac valvular surgery detected by long-term electrocardiographic monitoring. Am Heart J 911442-447 Mills S, Poole G, Breyer R et al. (1983) Digoxin and propranolo1 in the prophylaxis of dysrhythmias after coronary artery bypass grafting. Circulation 68 [Suppl II]: 222-225 Mohr R, Smolinsky A, Goor D (1981) Prevention of supraventricular tachyarrhythmia with low-dose propranolol after coronary bypass. J Thorac Cardiovasc Surg 81: 840-845 Rolfman J, Fieldman A (1981) Digoxin and propranolol in the prophylaxis of supraventticular tachydysrhythmias after coronary artery bypass surgery. Ann Thorac Surg 31:496-501 Silverman N, Wright R, Levitsky S (1982) Efficacy of low-dose propranolol in preventing postoperative supraventricular tachyarrhythmias. Ann Surg 196: 194-197 Smith E, Shore D, Monro J, Ross J (1985) Oral verapamil fails to prevent supraventricular tachycardia following coronary artery surgery. Int J Cardiol 9: 37-44 Smith P, Buhrman W, Levett J, Ferguson T, Holman W, Cox J (1983) Supraventricular conduction abnormalities following cardiac operations. J Thorac Cardiovasc Surg 85: 105-115 Stephenson LW, MacVaugh H, Tomasello D, Josephson M (1980) Propranolol for prevention of postoperative cardiac arrhythmias: a randomized study. Ann Thorac Surg 29: 1I3 - 116 Tchervenkov C, Wynands J, Symes J, Malcolm I, Dobell R, Morin J (1983) Persistent atria1 activity during cardioplegic arrest: a possible factor in the etiology or postoperative supraventricular tachyarrhythmias. Ann Thorac Surg 36437-443 Tyras D, Stothert J, Kaiser G, Barner H, Codd J, Willman V (1979) Supraventricular tachyarrhythmias after myocardial revascularization: a randomized trial of prophylactic digitalization. J Thorac Cardiovasc Surg 77: 310-313 White H, Antman E, Glynn M, Collins J, Cohn L, Shemin R, Friedman P (1984) Efficacy and safety of timolol for prevention of supraventricular tachyarrhythmias after coronary artery bypass surgery. Circulation 70: 479-484
References 1. Csicsko J, Schatzlein M, King R (1981) Immediate postoperative digitalization in the prophylaxis of supraventricular arrhythmias following coronary artery bypass. J Thorac Cardiovasc Surg 81: 419-422 2. Daudon P, Corcos T, Gandjbakhch I, Levasseur J, Cabrol A, Cabrol C (1986) Prevention of atria1 fibrillation or flutter by
Dr. R. W. Landymore Room 3065 R.C. Dickson Centre Victoria General Hospital Halifax, Nova Scotia, Canada B3H 2Y9
Surg (1991) 5:436-439
Surgery 0 Spring;-Verlag 1991
Recurrent atria1 arrhythmias following treatment for postoperative atria1 fibrillation after coronary bypass operations * R. W. Landymore and F. Howell Department
of Surgery, Division of Cardiovascular
Surgery, Dalhousie University,
Halifax, Nova Scotia, Canada
Abstract. Ambulatory Holter monitoring was performed in 58 patients during the early convalescence after myocardial revascularization in order to determine the incidence of recurrent atria1 arrhythmias following treatment for postoperative atria1fibrillation. Fifteen patients who had undergone coronary bypass and had not developed spontaneous atria1fibrillation following operation served as the controls (group 1). The remaining patients developed spontaneous symptomatic atria1 fibrillation after coronary bypass that required digitalization for rate control. Sixteen patients (group 2) continued taking digoxin for 8 weeks following operation, 13 patients (group 3) discontinued digoxin treatment 5 weeks following operation, and 14 patients (group 4) discontinued digoxin treatment 3 weeks following operation. Twenty-four-hour Holter monitoring indicated that asymptomatic atria1 fibrillation was common in the treatment groups after digitalization just before discharge from hospital. Atria1 fibrillation, however, rarely recurred following discharge from hospital and was never symptomatic. Our data indicate that patients who develop spontaneous postoperative atria1 fibrillation should be treated with digoxin for 3 weeks following operation and then drug therapy may be discontinued indefinitely. [Eur J Cardio-thorac Surg (1991) 5: 436-4391 Key words: Atria1 arrhythmia - Cardiac monitoring
Atria1 fibrillation occurs spontaneously in 8%-46% of patients following aortocoronary bypass operations [5, 161. The unheralded onset of supraventricular tachycardia is rarely associated with significant morbidity, although most patients require drug therapy and reinstitution of cardiac monitoring until the rapid ventricular response is controlled. The frequent occurrence of atria1 arrhythmias after cardiac operations has prompted numerous clinical trials that have investigated the efficacy of prophylactic antiarrhythmic drug therapy for the prevention of postoperative supraventricular arrhythmias [l-3, 5, 7, 8, 10, 11, 13, 14, 16, 181. However, there have been no clinical investigations that have specifically addressed the requirements for drug therapy following discharge from hospital. We felt that this was an important tissue to resolve, considering that many of our patients come from small, outlying communities where their convalescent care is provided solely by their personal physician. Frequently these patients may continue to take digoxin for protracted periods during their convalesReceived for publication: Accepted for publication: * Supported
March 4, 1991 May 2, 1991
by a New Brunswick Heart Foundation
Grant
cence. Thus, we designed this study, the aim of which was to determine the incidence of recurrent atria1 fibrillation after discharge in those patients who had required digitalization for symptomatic postoperative artrial fibrillation, in order to develop therapeutic guidelines for the pharmacological management of these patients during the early convalescence after coronary bypass. Patients and methods Fifty-eight patients undergoing elective myocardial revascularization gave informed consent to undergo 24-h Holter monitoring following operation. All patients undergoing coronary bypass operations were eligible to be entered into the study with the exception of patients requiring nonelective procedures and patients with a prior history of atria1 fibrillation. Cardiac anaesthesia was similar in all cases. Diazepam and papaveretum (Pantopon) were routinely used for preoperative sedation while anaesthesia was maintained with enflurane. Cardiopulmonary bypass was established with a single venous cannula while myocardial protection was provided with a combination of systemic cooling to 25 “C, multidose crystalloid cardioplegia (25 mEq K/l), and topical cooling. A combination of internal mammary artery and saphenous vein grafts were used for myocardial revascularization. Proximal and distal anastomoses were completed under a single aortic cross-clamp.
437
Patient subgroups The patients were prospectively randomized into two groups. Sixteen patients (group 2) were digitalized following the onset of atria1 fibrillation and instructed to continue taking digoxin for 8 weeks. Thirteen patients (group 3) were digitalized after developing spontaneous postoperative atria1 fibrillation and were instructed to discontinue digoxin 5 weeks after operation. Adequacy of digitalization was verified by measuring serum digoxin levels and by observing the therapeutic response to digitalization as evidenced by control of the tachycardia. The control group (group 1) was formed by 15 patients who had undergone coronary bypass and did not develop subsequent atria1 fibrillation. After the initial study was completed and the data were analysed, it became apparent that atria1 fibrillation was extremely uncommon following discharge from hospital in both treated groups. A further 14 patients (group 4) who had developed spontaneous atria1 fibrillation following coronary bypass were entered into the study to determine the effects of a shorter treatment period on the recurrence of postoperative atria1 arrhythmias. These patients were instructed to continue digoxin for only 3 weeks following operation.
Table 1. Patient profiles Age
Group 1
61
NYHA functional disability III
IV
IO
5
No. of grafts per pt.
Clamp time (min)
No. of pts. with intra-op AF
2.7
53
4
Group 2
61
12
4
2.5
51
3
Group 3
64
11
2
2.4
45
0
Group 4
59
10
4
3.0
59
3
NYHA = New York Heart Association;
Table 2. Holter monitoring l-3 No. of pts.
AF = atrial fibrillation
following coronary
Holter monitor before discharge
Holter monitoring Twenty-four-hour Holter monitoring was carried out just prior to discharge. All patients at this time were asymptomatic and had not complained of any paroxysms of atria1 tachycardia for at least 2-3 days prior to Holter monitoring. The control group and patients in groups 2 and 3 returned for further Holter monitoring at 3 and 6 weeks following operation, while the patients in group 4 underwent Holter monitoring prior to discharge and at 4 weeks following operation. Holter tapes were scanned manually for the presence of atria1 fibrillation and/or atria1 flutter. The electrophysiology laboratory reported the presence of atria1 tibrillation or atria1 flutter if more than four consecutive beats of the atria1 arrhythmia were present any time during the 24-h Holter monitoring.
Holter monitoring Results of the 24-h Holter monitoring are shown in Tables 2 and 3. Holter monitoring detected asymptomatic atria1 fibrillation in three patients in the control group just prior to discharge. Two patients experienced short runs of atria1 fibrillation, the longest run consisting of 18 beats. The third patient had a run of atria1 flutter for a duration of 191 beats. Patients in the treatment groups who had required digitalization for postoperative atria1 fibrillation did not have any recurrence of symptomatic atria1 arrhythmias after digitalization although 24-h
Atria1 fibrillation or flutter 3 wks after op.
6 wks after op.
Group 1
15
3 Patients 1. 1 Run 18 beats 2. 1 Run A-flutter 191 beats 3. 2 Runs longest 10 beats
Nil
Nil
Group 2
16
6 Patients 1. 1 Run 9 beats 2. 2 Runs longest 37 beats 3. 626 Runs longest 21 beats 4. 44 runs longest 520 beats 5. 2 Runs longest 9 beats 6. 53 Runs longest 519 beats
1 Patient 19 runs longest 512 beats
1 Patient 26 Runs longest 518 beats
Group 3
13
6 Patients 1. 593 Runs longest 21 beats 2. 650 Runs longest 212 beats 3. 1471 Runs longest 109 beats 4. Underlying rhythm mainly AF-A-flutter 5. Underlying rhythm mainly AF 6. Underlying rhythm mainly AF
Nil
Nil
Results
The patient profiles are displayed in Table 1. The four groups were similar with respect to age, functional disability, number of grafts and clamp time. Spontaneous intraoperative atria1 fibrillation occurred after unclamping of the aorta in a few patients in each group. The intra-operative atria1 arrhythmia was electrically cardioverted. Four patients in the control group and three patients in group 2 developed postpericardiotomy syndrome.
bypass in groups
’ Four consecutive beats were considered a run of atrial tibrillation
Holter monitoring detected runs of atria1 fibrillation in these groups. Holter monitoring detected atria1 fibrillation in six patients in group 2, six patients in group 3 and five patients in group 4. The number of runs of atria1 fibrillation and the duration of the longest run are given in tables. Although atria1 fibrillation was frequently detected during Holter monitoring, the ventricular rate was
438 Table 3. Holter monitoring
Group 4
following coronary bypass in group 4”
No. of pts.
Holter monitor before discharge
14
5 Patients 1. Underlying rhythm mainly AF
1. 2RunsofAF longest 16 beats
2. 63 Runs AF longest 41 beats
2. 1 Run AF 5 beats
3. 1 Run AF I beats
3. 1 Run AF $ beats
4. 53 Runs AF longest 56 beats
4. 5 Runs AF longest 22 beats
5. 1 Run AF 4 beats
5. 4 Runs atria1 longest 17 beats
Atria1 fibrillation or flutter 3 wks after operation
a Four consecutive beats were considered a run of atria1 fibrillation well-controlled which failed to generate any
explains
why
these
arrhythmias
symptomatology. Atria1 fibrillation was uncommon in the control group and in groups 2 and 3 three weeks following operation. There were no episodes of atria1 fibrillation in the control group or group 3, but Holter monitoring demonstrated asymptomatic atria1 fibrillation in one patient in group 2 taking digoxin. This patient had 19 runs of atria1 fibrillation, the longest run consisting of 512 beats. Group 4 had discontinued digoxin 3 weeks following operation and underwent Holter monitoring 1 week later. Five out of 14 patients had evidence of atria1 fibrillation and/or flutter; however, the runs of atria1 fibrillation were of short duration and were asymptomatic. Holter monitoring was repeated 6 weeks after operation in the control group and in groups 2 and 3. At this time group 2 was still taking digoxin while group 3 had discontinued the drug 5 weeks after operation and 1 week prior to ambulatory monitoring. There was no atria1 fibrillation recorded in the control group or group 3 at this time. However, asymptomatic atria1 fibrillation was demonstrated in one patient in group 2 taking digoxin. The Holter tape identified 26 runs of atria1 fibrillation, the longest run consisting of 518 beats. This patient had also showed Holter evidence of asymptomatic atria1 fibrillation at 3 weeks and was noted to have had postpericardiotomy syndrome following operation.
Discussion
Atria1 fibrillation occurs spontaneously in as many as one-third of patients undergoing aortocoronary bypass operations [5]. The actual incidence of clinical arrhythmias, however, is lower because many studies have included asymptomatic atria1 arrhythmias. Hammon et al. [5] reported a 46% incidence of atria1 fibrillation after coronary bypass but included arrhythmias that lasted less than 10 s. White and associates [19] indicated that supraventricular tachycardia occurred in 35% of patients but included tachycardias that lasted less than 10 s or for a duration of 10 beats. Similarly, Janssen et al. [7] re-
ported a 36% incidence of supraventricular tachycardia after coronary bypass but included arrhythmias that lasted less than 1 min. The incidence of symptomatic postoperative atria1 fibrillation, however, is considerably lower and lies within a range of 16%-30% [8,10,13,18]. The prophylactic use of drug therapy to prevent postoperative atria1 fibrillation after coronary bypass has received considerable attention but has met with conflicting results. Mills et al. [lo] and Csiscko et al. [l] have indicated that prophylactic digitalization reduces the incidence of postoperative supraventricular tachycardia while Tyras and associates [18] observed that prophylactic digitalization increased the number of postoperative supraventricular arrhythmias. Smith and colleagues [14] reported that low-dose verapamil treatment failed to reduce the incidence of postoperative atria1 arrhythmias. In contrast, Davidson et al. [3] demonstrated that verapamil reduced the incidence of supraventricular tachyarrhythmias but cautioned against the prophylactic use of verapamil because its administration had frequently precipitated hypotension. Numerous clinical trials have examined the effects of beta-blockers on the incidence of postoperative supraventricular tachycardia. A review of these studies indicates that the prophylactic use of propranolol, or more selective beta-blockers, will significantly reduce but not prevent postoperative atria1 fibrillation [2, 8, 11, 13, 161. The aetiology of atria1 fibrillation after coronary bypass is uncertain. Smith and colleagues [15], in an experimental study, suggested that atria1 arrhythmias were related to inadequate atria1 and atrioventricular nodal protection during cardioplegic arrest after they demonstrated that the atrium received far less cardioplegia then the myocardium. They also discovered that the atria1 temperature rose almost immediately following the infusion of cardioplegia and that the atrium was always warmer than the myocardium. Tchervenkov and associates [I 71have also indicated that postoperative supraventricular tachyarrhythmias may be a manifestation of inadequate atria1 protection by demonstrating an association between the duration of atria1 activity during cardioplegic arrest and the occurrence of postoperative atria1 fibrillation. Although inadequate atria1 protection may play a role in the development of postoperative supraventricular tachycardia, the aetiology is probably multifactorial rather than related to a single determinant factor, as atria1 arrhythmias have been reported not only after interminant aortic cross-clamping [1,9,18] but after the use of cardioplegia [5, 10, 171. Furthermore, clinical studies reported by Rolfman and Fieldman [12] and Dixon et al. [4] have shown that older age, clamp time, left atria1 enlargement and cardiomegaly are associated with postoperative supraventricular arrhythmias. Atria1 fibrillation frequently complicates the postoperative convalescence of our patients following coronary bypass operations, but it is rarely associated with significant morbidity. Electrocardiographic monitoring in the intensive care unit will often demonstrate the presence of multiple premature atria1 contractions just prior to the onset of this arrhythmia, which usually becomes manifest within the first 4 days following operation. Rate control
439
and bedside monitoring are indicated in almost all patients following the onset of rapid atria1 fibrillation. Intravenous digitalization usually controls the ventricular response in most patients, although intravenously administered propranolol and/or verapamil may be required initially to control the ventricular rate. Cardioversion is only occasionally necessary in the rare patient who develops haemodynamic compromise. Ambulatory Holter monitoring has demonstrated that some patients may develop asymptomatic atria1 fibrillation or flutter within the first few days following a coronary bypass operation. Twenty percent of our control group had Holter evidence of atria1 fibrillation after operation without being aware of the arrhythmia. Twenty-four-hour Holter monitoring of the treatment groups indicated that atria1 fibrillation frequently reoccurs after digitalization. Slightly less than one-half of the patients in the treatment groups had episodes of asymptomatic atria1 fibrillation after digitalization, but these patients were unaware of their arrhythmias because the rate of the supraventricular tachycardia had been adequately controlled by drug therapy. There were no symptomatic atria1 arrhythmias after discharge from hospital. Holter monitoring failed to detect any arrhythmias in the control group and group 3, while there was only one patient with Holter evidence of atria1 fibrillation in group 2. Even the patients in group 4 had no significant atria1 arrhythmias, after taking digoxin for only 3 weeks following the initial treatment of atria1 fibrillation. Ambulatory monitoring, therefore, has shown that postoperative atria1 fibrillation is a transient arrhythmia that rarely recurs after initial treatment and discharge from hospital.
Conclusion
Atria1 fibrillation is a common but extremely transient arrhythmia following coronary bypass operations. The arrhythmia requires digitalization for rate control but does not require prolonged drug therapy. It is our practise now to digitalize patients initially after onset of the arrhythmia and then only treat these patients for a period of 3 weeks. This treatment regimen has not resulted in recurrence of symptomatic atria1 arrhythmias in any of our patients after coronary bypass operations.
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18. Acknowledgement. We would like to thank C. E. Kinley, MD, FRCSC, D. A. Murphy, MD, FRCSC, and J. Wood, MD, FRCSC, for allowing us to investigate some of their patients. 19.
acebutolol after coronary bypass grafting. Am J Cardioi 58: 933-936 Davison R, Hartz R, Kaplan K, Parker M, Feiereisel P, Michaelis L (1985) Prophylaxis of supraventricular tachyarrhythmia after coronary bypass surgery with oral verapamil: a randomized, double-blind trial. Ann Thorac Surg 39: 336-339 Dixon F, Genton E, Vacek J, Moore C, Landry J (1986) Factors predisposing to supraventricular tachyarrhythmias after coronary artery bypass grafting. Am J Cardiol 58:476-478 Hammon JW, Wood A, Prager R, Wood M, Muirhead J, Bender H (1984) Perioperative beta blockade with propranolol: reduction in myocardial oxygen demands and incidence of atria1 and ventricular arrhythmias. Ann Thorac Surg 38: 363 -367 Ivey M, Ivey T, Bailey W, Williams D, Hessel E, Miller D (1983) Influence of propranolol on supraventricular tachycardia early after coronary artery revascularization. J Thorac Cardiovasc Surg 85: 214-218 Janssen J, Loomans L, Harink J, Taams M, Brunninkhuis L, van der Starre P, Kootstra G (1986) Prevention and treatment of supraventricular tachycardia shortly after coronary artery bypass grafting: a randomized open trial. Angiology 37: 601-608 Matangi M, Neutze J, Graham K, Hill D, Kerr A, BarrettBoyes B (1985) Arrhythmia prophylaxis after aorta-coronary bypass. J Thorac Cardiovasc Surg 89: 439-443 Michelson E, Morganroth J, MacVaugh H (1979) Postoperative arrhythmias after coronary artery and cardiac valvular surgery detected by long-term electrocardiographic monitoring. Am Heart J 911442-447 Mills S, Poole G, Breyer R et al. (1983) Digoxin and propranolo1 in the prophylaxis of dysrhythmias after coronary artery bypass grafting. Circulation 68 [Suppl II]: 222-225 Mohr R, Smolinsky A, Goor D (1981) Prevention of supraventricular tachyarrhythmia with low-dose propranolol after coronary bypass. J Thorac Cardiovasc Surg 81: 840-845 Rolfman J, Fieldman A (1981) Digoxin and propranolol in the prophylaxis of supraventticular tachydysrhythmias after coronary artery bypass surgery. Ann Thorac Surg 31:496-501 Silverman N, Wright R, Levitsky S (1982) Efficacy of low-dose propranolol in preventing postoperative supraventricular tachyarrhythmias. Ann Surg 196: 194-197 Smith E, Shore D, Monro J, Ross J (1985) Oral verapamil fails to prevent supraventricular tachycardia following coronary artery surgery. Int J Cardiol 9: 37-44 Smith P, Buhrman W, Levett J, Ferguson T, Holman W, Cox J (1983) Supraventricular conduction abnormalities following cardiac operations. J Thorac Cardiovasc Surg 85: 105-115 Stephenson LW, MacVaugh H, Tomasello D, Josephson M (1980) Propranolol for prevention of postoperative cardiac arrhythmias: a randomized study. Ann Thorac Surg 29: 1I3 - 116 Tchervenkov C, Wynands J, Symes J, Malcolm I, Dobell R, Morin J (1983) Persistent atria1 activity during cardioplegic arrest: a possible factor in the etiology or postoperative supraventricular tachyarrhythmias. Ann Thorac Surg 36437-443 Tyras D, Stothert J, Kaiser G, Barner H, Codd J, Willman V (1979) Supraventricular tachyarrhythmias after myocardial revascularization: a randomized trial of prophylactic digitalization. J Thorac Cardiovasc Surg 77: 310-313 White H, Antman E, Glynn M, Collins J, Cohn L, Shemin R, Friedman P (1984) Efficacy and safety of timolol for prevention of supraventricular tachyarrhythmias after coronary artery bypass surgery. Circulation 70: 479-484
References 1. Csicsko J, Schatzlein M, King R (1981) Immediate postoperative digitalization in the prophylaxis of supraventricular arrhythmias following coronary artery bypass. J Thorac Cardiovasc Surg 81: 419-422 2. Daudon P, Corcos T, Gandjbakhch I, Levasseur J, Cabrol A, Cabrol C (1986) Prevention of atria1 fibrillation or flutter by
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