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

The aim of this study was to evaluate the treatment and outcomes of patients with ST-segment 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 sixty-eight 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 ST-segment 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.