Out-of-Hospital Cardiac Arrest in Apparently Healthy, Young Adults

Abstract

Importance: Out-of-hospital cardiac arrest incidence in apparently healthy adults younger than 40 years ranges from 4 to 14 per 100 000 person-years worldwide. Of an estimated 350 000 to 450 000 total annual out-of-hospital cardiac arrests in the US, approximately 10% survive.

Observations: Among young adults who have had cardiac arrest outside of a hospital, approximately 60% die before reaching a hospital (presumed sudden cardiac death), approximately 40% survive to hospitalization (resuscitated sudden cardiac arrest), and 9% to 16% survive to hospital discharge (sudden cardiac arrest survivor), of whom approximately 90% have a good neurological status (Cerebral Performance Category 1 or 2). Autopsy-based studies demonstrate that 55% to 69% of young adults with presumed sudden cardiac death have underlying cardiac causes, including sudden arrhythmic death syndrome (normal heart by autopsy, most common in athletes) and structural heart disease such as coronary artery disease. Among young adults, noncardiac causes of cardiac arrest outside of a hospital may include drug overdose, pulmonary embolism, subarachnoid hemorrhage, seizure, anaphylaxis, and infection. More than half of young adults with presumed sudden cardiac death had identifiable cardiovascular risk factors such as hypertension and diabetes. Genetic cardiac disease such as long QT syndrome or dilated cardiomyopathy may be found in 2% to 22% of young adult survivors of cardiac arrest outside of the hospital, which is a lower yield than for nonsurvivors (13%-34%) with autopsy-confirmed sudden cardiac death. Persons resuscitated from sudden cardiac arrest should undergo evaluation with a basic metabolic profile and serum troponin; urine toxicology test; electrocardiogram; chest x-ray; head-to-pelvis computed tomography; and bedside ultrasound to assess for pericardial tamponade, aortic dissection, or hemorrhage. Underlying reversible causes, such as ST elevation myocardial infarction, coronary anomaly, and illicit drug or medication overdose (including QT-prolonging medicines) should be treated. If an initial evaluation does not reveal the cause of an out-of-hospital cardiac arrest, transthoracic echocardiography should be performed to screen for structural heart disease (eg, unsuspected cardiomyopathy) or valvular disease (eg, mitral valve prolapse) that can precipitate sudden cardiac death. Defibrillator implant is indicated for young adult sudden cardiac arrest survivors with nonreversible cardiac causes including structural heart disease and arrhythmia syndromes.

Conclusions and relevance: Cardiac arrest in apparently healthy adults younger than 40 years may be due to inherited or acquired cardiac disease or noncardiac causes. Among young adults who have had cardiac arrest outside of a hospital, only 9% to 16% survive to hospital discharge. Sudden cardiac arrest survivors require comprehensive evaluation for underlying causes of cardiac arrest and cardiac defibrillator should be implanted in those with nonreversible cardiac causes of out-of-hospital cardiac arrest.

Figure 1.. Worldwide Incidence of Out-of-Hospital Cardiac Arrest, Presumed Sudden Cardiac Death, and Sudden Cardiac Death in Young Adults

^aMeeting Cardiac Arrest Registry to Enhance Survival (CARES) criteria emergency medical service primary impression “cardiac arrest.” ^bIncludes pulmonary embolism, overdose, hemorrhage, neurological, diabetic ketoacidosis, sepsis, gastrointestinal disorders, aortic aneurysm, aortic dissection. ^cStructural heart disease includes coronary artery disease, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy, valvular heart disease (mitral valve prolapse, aortic stenosis), left ventricular hypertrophy, myocarditis. ^dSudden arrhythmic death syndrome, also referred to as primary electrical disease with normal heart or unexplained sudden cardiac death in nonsurvivors. This condition is termed primary arrhythmia syndrome in survivors. ^eTamponade, myocardial infarction with wall rupture, acute heart failure with pulmonary edema. WHO indicates World Health Organization.

Figure 2.. Evaluation of the Resuscitated Young Adult Sudden Cardiac Arrest Patient

^aIncludes aortic dissection, gastrointestinal bleeding, diabetic ketoacidosis, infection, neurologic causes, overdose, pulmonary embolism, renal failure, respiratory causes. ^bIncludes chronic coronary artery disease, cardiomyopathy (eg, arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy, hypertrophic cardiomyopathy, left ventricular noncompaction), hypertrophy, myocarditis, sarcoidosis, valvular heart diseases (eg, mitral valve prolapse). ^cIncludes long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, idiopathic ventricular fibrillation, bradyarrhythmias. ICD indicates implantable cardioverter-defibrillator.

Figure 3.. Representative Electrocardiographs of High-Risk Arrhythmia Conditions

B, The black arrowhead points to the coved ST elevation. C, The pink arrowheads point to the delta wave. D, The blue arrowheads point to the epsilon wave.