Coronary Artery Disease
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

https://doi.org/10.1016/j.amjcard.2014.07.006Get rights and content

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.

Section snippets

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

Results

From January 1, 2011, to June 30, 2012, a total of 1,289 patients with OOHCA with restoration of spontaneous circulation were transported to 34 participating hospitals. Of these patients, 348 patients were diagnosed with STEMIs on the basis of prehospital and/or initial hospital electrocardiographic findings made up the study cohort. Of the patients with STEMIs, a total of 52 patients (15%) died in the emergency department. Two hundred nineteen patients (63%) went to the cardiac catheterization

Discussion

This study reinforces the significance of a shockable arrest rhythm on the outcomes of patients with OOHCA plus STEMI. Although the OOHCA plus STEMI population has substantially better survival than the broader OOHCA population, initial arrest rhythm remains as a strong predictor of outcomes. This finding persists even in the “true” STEMI population treated in the cardiac catheterization laboratory. It is unclear whether the arrest rhythm distinction reflects different pathophysiology or

Disclosures

The authors have no conflicts of interest to disclose.

References (19)

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Cited by (19)

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    The shockable ECG rhythms comprising ventricular fibrillation (VF) and ventricular tachycardia (VT) can potentially revert to normal sinus rhythm with the restoration of adequate cardiac pump function upon emergency administration of electrical shock delivered via implantable cardioverter-defibrillator devices [5] or automatic external defibrillator (AED) [4]. In contrast, shock therapy will neither reestablish sinus rhythm, nor cardiac flow in non-shockable rhythms, which comprise asystole (absent electrical activity in the heart) and pulseless electrical activity, where electromechanical decoupling disables heart contraction despite organized electrical heart rhythm [2,4–7,120,121]. Given that downstream management and prognosis are based on the correct ECG interpretation during cardiac arrest, artificial intelligence (AI) methods have been increasingly incorporated into computer-aided arrhythmia classification (CAAC) systems to enhance the accuracy of real-time detection of shockable ECG rhythms [9–11].

  • Characteristics and outcomes of in-hospital cardiac arrest in adults hospitalized with acute coronary syndrome in China

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    ACS has three different diagnoses, including acute ST-elevation myocardial infarction (STEMI), non-STEMI (NSTEMI) and unstable angina (UA) [5]. Previous studies have focused on highly selected myocardial infarction (MI) patients undergoing PCI or coronary artery bypass graft surgery (CABG), including STEMI [1,6,7] and NSTEMI [8,9], with the majority of the published studies conducted on patients suffering sudden death [10,11] or out-of-hospital cardiac arrest [12,13]. Few studies have been performed to investigate resuscitation outcomes after IHCA, based on an unselected cohort.

  • Prognostic significance of shockable and non-shockable cardiac arrest in ST-segment elevation myocardial infarction patients undergoing primary angioplasty

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    In a large nation-based retrospective study [6] including the whole spectrum of STEMI (regardless the presence or the type of reperfusion therapy), patients with CA due to asystole were at increased risk of 30-day mortality compared to patients with either ventricular arrhythmia or pulseless electrical activity. In the setting of PPCI, few studies enrolling small [7–9] or selected [10] series of STEMI patients showed that CA with non-shockable rhythm is associated with an increased risk of mortality compared to patients experiencing a CA with an initial shockable rhythm. Thus, objectives of the present study enrolling a large unselected cohort of patients undergoing PPCI in the context of a territorial network for STEMI treatment were the following: 1) to evaluate the risk of 1 year cardiac mortality in patients with initial shockable CA and non-shockable CA as compared to patients without CA, 2) to determine in patients with CA the independent predictors of both 1-y cardiac mortality and 3) poor neurological outcome.

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