Sudden cardiac arrest with shockable rhythm in patients with heart failure

BACKGROUND Patients with shockable sudden cardiac arrest (SCA; ventricular fibrillation/tachycardia) have significantly better resuscitation outcomes than do those with nonshockable rhythm (pulseless electrical activity/asystole). Heart failure (HF) increases the risk of SCA, but presenting rhythms have not been previously evaluated. OBJECTIVE We hypothesized that based on unique characteristics, HFpEF (HF with preserved ejection fraction; left ventricular ejection fraction [LVEF] >= 50%), bHFpEF (HF with borderline preserved ejection fraction; LVEF >40% and <50%), and HFrEF (HF with reduced ejection fraction; LVEF <= 40%) manifest differences in presenting rhythm during SCA. METHODS Consecutive cases of SCA with HF (age >= 18 years) were ascertained in the Oregon Sudden Unexpected Death Study (2002-2019). LVEF was obtained from echocardiograms performed before and unrelated to the SCA event. Presenting rhythms were identified from first responder reports. Logistic regression was used to evaluate the independent association of presenting rhythm with HF subtype. RESULTS Of 648 subjects with HF and SCA (median age 72 years; interquartile range 62-81 years), 274 had HFrEF (23.4% female), 92 had bHFpEF (35.9% female), and 282 had HFpEF (42.5% female). The rates of shockable rhythms were 44.5% (n = 122), 48.9% (n = 45), and 27.0% (n = 76) for HFrEF, bHFpEF, and HFpEF, respectively ( P < .001). Compared with HFpEF, the adjusted odds ratios for shockable rhythm were 1.86 (95% confidence interval 1.27-2.74; P = .002) in HFrEF and 2.26 (95% CI 1.35-3.77; P = .002) in bHFpEF. The rates of survival to hospital discharge were 10.6% (n = 29) in HFrEF, 22.8% (n = 21) in bHFpEF, and 9.9% (n = 28) in HFpEF ( P = .003). CONCLUSION The rates of shockable rhythm during SCA depend on the HF clinical subtype. Patients with bHFpEF had the highest likelihood of shockable rhythm, correlating with the highest rates of survival.