Outcome of Apparently Unexplained Cardiac Arrest

Abstract

Background— The Cardiac Arrest Survivors with Preserved Ejection Fraction Registry (CASPER) enrolls patients with apparently unexplained cardiac arrest and no evident cardiac disease to identify the pathogenesis of cardiac arrest through systematic clinical testing. Exercise testing, drug provocation, advanced cardiac imaging, and genetic testing may be useful when a cause is not apparent. Methods and Results— The first 200 survivors of unexplained cardiac arrest from 14 centers across Canada were evaluated to determine the results of investigation and follow-up (age, 48.6±14.7 years, 41% female). Patients were free of evidence of coronary artery disease, left ventricular dysfunction, or evident repolarization syndromes. Advanced testing determined a diagnosis in 34% of patients at baseline, with a diagnosis emerging during follow-up in 7% of patients. Of those who were diagnosed, 28 (35%) had an underlying structural condition and 53 (65%) had a primary electric disease. During a mean follow-up of 3.15±2.34 years, 23% of patients had either a shock or an appropriate antitachycardia pacing from their implantable cardioverter defibrillator, or both. The implantable cardioverter defibrillator appropriate intervention rate was 8.4% at 1 year and 18.1% at 3 years, with no clear difference between diagnosed and undiagnosed subjects, or between those diagnosed with a primary electric versus structural pathogenesis. Conclusions— Obtaining a diagnosis in previously unexplained cardiac arrest patients requires systematic clinical testing and regular follow-up to unmask the cause. Nearly half of apparently unexplained cardiac arrest patients ultimately received a diagnosis, allowing for improved treatment and family screening. A substantial proportion of patients received appropriate implantable cardioverter defibrillator therapy during medium-term follow-up. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00292032.

Sudden Cardiac Death and Arrhythmias

“…40 In patients who have an ICD implanted, further appropriate ICD therapy is seen in >23 % of cases. 32 Identifying the cause of the cardiac arrest is important as this may allow directed therapy that reduces the risk of future cardiac arrest, and may also allow for the identification and prevention of the same, potentially inherited, condition in first-degree relatives.…”

“…Additionally, structural cardiac abnormalities, Patients Where the Cardiac Arrest is Apparently Unexplained: The Barts Protocol Where cases of ischaemic heart disease are excluded, EF is preserved and repolarisation disorders are not apparent on the resting ECG, further assessment is required. This may increase the diagnostic yield and provide a diagnosis in nearly half of patients where aninitial diagnosis is unclear 32.…”

Significance of Coronary Artery Spasm Diagnosis in Patients With Early Repolarization Syndrome

“…The prevalence of CAS in patients resuscitated from cardiopulmonary arrest is 7.4% in Japan3 and 8.6% in Western countries 6. In addition, inferolateral J wave has been reported in 21% to 36% of patients with CAS 9, 10.…”

“…The prevalence of CAS in patients resuscitated from cardiopulmonary arrest ranges from 3.3% to 8.6% 3, 4, 5, 6. It is known that CAS may induce fatal ventricular arrhythmias without apparent chest symptoms 7, 8.…”

Life-long tailoring of diagnosis and management of patients with idiopathic ventricular fibrillation—future perspectives in research

“…Therefore, follow-up and re-evaluation of the diagnosis are important aspects of the management of patients with idiopathic ventricular fibrillation. Of patients with idiopathic ventricular fibrillation, 7 to 35% reveal a different diagnosis during follow-up due to disease progression or more extensive or more sophisticated diagnostic evaluation [9–13]. Since the underlying disease substrate is often not known, discovery of new disease entities and novel diagnostic techniques can reveal causes not detectable or known during initial evaluation.…”