Prognostic Value of Heart Rate Preceding Ventricular Tachyarrhythmias Among ICD Patients With Left Ventricular Dysfunction.

Studies of heart failure with reduced ejection fraction (HFrEF) and preserved ejection fraction (HFpEF) report high sudden cardiac death (SCD) rates but presume cardiac cause. Underlying causes, guideline-directed medical therapy (GDMT), and implantable cardioverter-defibrillator (ICD) use in community sudden deaths with heart failure (HF) are unknown.This study aims to assess the burden of HF, GDMT, and ICD use among autopsied sudden deaths in the POST SCD (Postmortem Systematic Investigation of Sudden Cardiac Death) study, a countywide postmortem study of all presumed SCDs.Incident WHO-defined (presumed) SCDs for individuals of ages 18 to 90 years were autopsied via prospective surveillance of consecutive out-of-hospital deaths in San Francisco County from February 1, 2011, to March 1, 2014. Sudden arrhythmic deaths (SADs) had no identifiable nonarrhythmic cause (eg, pulmonary embolism), and are thus considered potentially rescuable with ICD.Of 525 presumed SCDs, 100 (19%) had HF. There were 85 patients with known HF (31 HFpEF, 54 HFrEF) and 15 with subclinical HF (postmortem evidence of cardiomyopathy and pulmonary edema without HF diagnosis). SADs comprised 56% (293 of 525) of all presumed SCDs, and 69% (69 of 100) of HF SCDs. The rates were similar in HFrEF (40 of 54 [74%]) and HFpEF (19 of 31 [61%], P = 0.45). Four SAD patients (4%) had ICDs, 3 of which experienced device failure. Twenty-eight SCDs had ejection fraction ≤35%: 22 (79%) with arrhythmic and 6 (21%) with noncardiac causes. Of the 22 SAD patients, 8 (36%) had no identifiable barrier to ICD referral. Complete use of GDMT in HFrEF was 6%.One in 5 community sudden deaths had HF; two-thirds had autopsy-confirmed arrhythmic causes. ICD prevention criteria captured only 8% (22 of 293) of all SAD cases countywide; GDMT and ICD use remain important targets for HF sudden death prevention.