Treatment and Outcomes of ST Segment Elevation Myocardial Infarction and Out-of-Hospital Cardiac Arrest in a Regionalized System of Care Based on Presence or Absence of Initial Shockable Cardiac Arrest Rhythm Joseph L. Thomas, MDa,*, Nichole Bosson, MDb, Amy H. Kaji, MDb, Yong Ji, BAc, Gene Sung, MDd, David M. Shavelle, MDe, William J. French, MDa, William Koenig, MDf, and James T. Niemann, MDb The aim of this study was to evaluate the treatment and outcomes of patients with STsegment elevation myocardial infarctions complicated by out-of-hospital cardiac arrest in a regional system of care. In this retrospective study, the effect of the absence of an initial shockable arrest rhythm was analyzed. The primary end point of survival with good neurologic outcome in patients with and without an initial shockable arrest rhythm was adjusted for age, witnessed arrest, bystander cardiopulmonary resuscitation, and treatment with therapeutic hypothermia and percutaneous coronary intervention. One-hundred sixtyeight of 348 patients (49%) survived to hospital discharge. Patients with a shockable initial rhythm were more likely to receive therapeutic hypothermia (48% vs 37%, risk ratio 1.2, 95% confidence interval [CI] 1.0 to 1.5) and to be treated in the cardiac catheterization laboratory (80% vs 43%, risk ratio 2.8, 95% CI 2.0 to 3.8). The likelihood of survival with good neurologic outcome in patients with a shockable initial rhythm compared with those presenting without a shockable rhythm was 4.8 (95% CI 2.7 to 8.7). In patients who underwent percutaneous coronary intervention, the likelihood of survival with good neurologic outcome was higher (risk ratio 2.7, 95% CI 1.1 to 6.8) in those with a shockable rhythm. In conclusion, the absence of an initial shockable rhythm in patients with STsegment elevation myocardial infarctions plus out-of-hospital cardiac arrest is associated with significantly worse survival and neurologic outcome. These differences persist despite application of therapies including therapeutic hypothermia and percutaneous coronary intervention within a regionalized system of care. Ó 2014 Elsevier Inc. All rights reserved. (Am J Cardiol 2014;114:968e971) Available data suggest that out-of-hospital cardiac arrest (OOHCA) and OOHCA with ST-segment elevation myocardial infarction (STEMI) represent different pathophysiologic entities with divergent outcomes. Patients with OOHCA plus STEMI have a better prognosis than the overall OOHCA population without STEMI.1 From a prognostic standpoint, it may be possible to further distinguish patients with OOHCA plus STEMI by initial arrest rhythm. This distinction may be of great importance to patient management, health system planning, and outcomes reporting. The purpose of this study was to compare the characteristics, treatment, and outcomes of patients with OOHCA plus STEMI with and without a shockable initial rhythm in a regional system of care with mandated therapeutic

a Division of Cardiology and bDepartment of Emergency Medicine, Harbor UCLA Medical Center, Torrance, California; cAlbany Medical College, Albany, New York; dDepartment of Neurology and eDivision of Cardiology, University of Southern California, Los Angeles, California; and fLos Angeles County Emergency Medical Services Agency, Los Angeles, California. Manuscript received March 18, 2014; revised manuscript received and accepted July 2, 2014. See page 971 for disclosure information. *Corresponding author: Tel: 310-222-2544; fax: 310-787-0448. E-mail address: [email protected] (J.L. Thomas).

0002-9149/14/$ - see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.amjcard.2014.07.006

hypothermia (TH) and primary percutaneous coronary intervention (PCI).

Methods In 2006, Los Angeles County established regionalized cardiac care for STEMI with a network of designated STEMI receiving centers. These centers are capable of providing immediate primary PCI 24 hours per day, and they are required to have robust quality improvement programs and internal policies for PCI and TH. Since 2010, all patients with OOHCA of presumed cardiac origin with restoration of spontaneous circulation in the field have been transported to these STEMI centers. Participating centers are encouraged to institute TH (target temperature 32
to 34
C) in all eligible patients