Streamlined triage and delivery of patients with out-of-hospital cardiac arrest to dedicated heart attack centers can improve functional status and survival, according to an observational study published online January 6, 2015, ahead of print in the American Journal of Cardiology.

Consequently, this research “supports the standardization of care for such patients with the widespread adoption of [heart attack centers],” M. Bilal Iqbal, MD, of Harefield Hospital (Middlesex, England), and colleagues say.

In London, if ambulance personnel decide the etiology of an out-of-hospital cardiac arrest is primarily cardiac, they are permitted to bypass the nearest hospital and take patients to dedicated “heart attack centers” for immediate catheterization and revascularization, if warranted.

Dr. Iqbal and his team analyzed data on 174 patients with out-of-hospital cardiac arrest who were brought to Harefield Hospital—an urban heart attack center—between 2011 and 2013. Functional status at discharge was assessed by using a modified Rankin Scale (mRS), with favorable status defined as scores of 0-3 and poor status as scores of 4-6.

Better Functional Equals Better Survival

Less than two-thirds of patients (63.5%) survived until discharge. In all, 54.6% of discharged patients were categorized as having favorable functional status.

Of those successfully resuscitated, the overall mortality rates were 33.3% and 37.9% at 30 days and 1 year, respectively.

Patients with better function were less likely that those with worse function to die at 30 days (1% vs 72%; P < .001) and 1 year (5.3% vs 77.2%; P < .001). Moreover, Cox proportional hazards regression models found favorable function to predict higher odds of survival at both 30 days and 1 year (adjusted HR 0.03; 95% CI 0.01-0.08)—a result also confirmed through Kaplan-Meier analysis.

Predictors of better function were bystander CPR and ventricular tachycardia or ventricular fibrillation (VT/VF) as initial presenting rhythm, while a higher Charlson Comorbidity Index score, cardiogenic shock, adrenaline administration, and longer duration of resuscitation were associated with worse function (table 1).

In an in-hospital adjusted model, use of intraaortic balloon pump and absence of inotropic support also were identified as independent predictors of favorable functional status.

On multivariate Cox proportional analysis, presence of cardiogenic shock, prehospital use of advanced airway, increased duration of resuscitation, and absence of therapeutic hypothermia all were associated with higher mortality at 30 days and 1 year.

Furthermore, with each added minute of resuscitation the likelihood of surviving with favorable functional status “falls exponentially,” with the optimal duration of resuscitation lasting 8 minutes or less, the researchers say. The specificity for predicting favorable functional status was high for resuscitation lasting 3 minutes or less and decreased each minute thereafter.

Though catheterization predicted 30-day mortality, the association did not remain at 1 year. Upcoming results of the ARREST trial may help resolve the question of whether cardiac catheterization should be used in patients with VT/VF but without ST elevation, the researchers note.

Bystander CPR, Duration of Resuscitation Key to Good Outcomes

Sripal Bangalore, MD, MHA, of New York University School of Medicine (New York, NY),told TCTMD in an email that “the study reinforces many of the factors for survival that we had known previously.”

“Although the study does not provide direct comparison data for heart attack centers vs non–heart attack centers, the lower mortality does point to the benefits of having designed such centers of care where there are protocols in place for such a high-risk group of patients,” Dr. Bangalore explained, adding that “some states in the US have something similar. In New York City, patients with STEMI are usually routed to primary PCI centers.”

“It’s good to reinforce to the public that every minute counts and the first 3 minutes are exceedingly important after a cardiac arrest,” he stated. Though the results of this study are unsurprising, Dr. Bangalore said, they may impart “greater awareness of the duration of resuscitation and importance of bystander CPR on both functional status and outcomes.”

Dr. Iqbal and colleagues say the study demonstrates “that triaging patients to dedicated facilities is associated with improved survival and functional outcomes.” As a result, they recommend a “standardization of care for such patients [and] the widespread adoption of [heart attack centers].”

Source:
Iqbal MB, Al-Hussaini A, Rosser G, et al. Predictors of survival and favourable functional outcomes following an out of hospital cardiac arrest in patients systematically brought to a dedicated heart attack centre (from the Harefield cardiac arrest study). Am J Cardiol. 2015;Epub ahead of print.

Disclosures:

• The paper contains no statement regarding conflicts of interest for Dr. Iqbal.
• Dr. Bangalore reports no relevant conflicts of interest.

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