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Survival by Cause of Cardiac Arrest After Resuscitation
Quick Takes
- In this study of out-of-hospital cardiac arrests, only one-third were sudden, of which one-half were resuscitated to hospitalization and one in five survived to discharge.
- Underlying cause had a significant impact on survival, with arrhythmic cause found in 92% of sudden cardiac arrest patients who survived to hospital discharge but in only 57% of nonsurvivors.
- Several noncardiac conditions predispose to high mortality among initial survivors of out-of-hospital cardiac arrest, including stroke, sepsis, and pulmonary embolism.
Study Questions:
What are the causes and outcomes of resuscitated sudden cardiac arrests (SCAs)?
Methods:
Among out-of-hospital cardiac arrests (OHCAs) in San Francisco County, the authors identified subjects who had been resuscitated from SCA and survived to hospitalization. Whether the event was a true SCA or just sudden death from another cause was determined by comprehensive pre-event and post-event medical record review.
Results:
The authors identified a total of 734 OHCAs. About one-third of them (239 subjects) met SCA criteria. Among the bona fide SCA cases, 133 (56%) lived to hospitalization, and 47 (20%) survived to discharge. Arrhythmic causes accounted for significantly more resuscitated SCAs overall (92 of 133, 69%), particularly among survivors (43 of 47, 92%), than World Health Organization (WHO)-defined sudden cardiac deaths (SCDs) in the San Francisco POST SCD Study (Postmortem Systematic Investigation of Sudden Cardiac Death, 293 of 525, 56%; p < 0.004 for both). Among resuscitated SCAs, arrhythmic cause, ventricular tachycardia/fibrillation as initial rhythm, and white race were independent predictors of survival. None of the resuscitated SCAs due to neurologic causes survived.
Conclusions:
In this study of OHCAs, only one-third of the events were sudden, of which one-half were resuscitated to hospitalization, and one in five survived to discharge. Arrhythmic cause predicted survival and nearly one-half of nonsurvivors had nonarrhythmic causes, suggesting that SCAs are not equivalent to SCDs.
Perspective:
In this important study, the authors attempt to define outcomes among patients with a genuine SCA, as opposed to SCD, which has been defined by the WHO as sudden unexpected death either within 1 hour of symptom onset (event witnessed), or within 24 hours of having been observed alive and symptom free (unwitnessed). Many studies have equated the outcomes of SCA and SCD, and in most reports, the basis for determination of arrhythmic cause is determined solely from the emergency medical services records. The present study shows that among patients who survive SCD and are discharged to home, arrhythmic etiology is by far the most common, while those who succumb early in the chain of survival commonly have noncardiac conditions. More precise identification of arrhythmia and nonarrhythmic causes is likely to focus further research on specific targets for intervention.
Clinical Topics: Acute Coronary Syndromes, Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Prevention, Vascular Medicine, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure
Keywords: Arrhythmias, Cardiac, Acute Coronary Syndrome, Death, Sudden, Cardiac, Heart Arrest, Heart Failure, Medical Records, Out-of-Hospital Cardiac Arrest, Patient Discharge, Pulmonary Embolism, Resuscitation, Secondary Prevention, Sepsis, Stroke, Survivors, Tachycardia, Ventricular, Ventricular Fibrillation
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