Risk of arrhythmic death in ischemic heart disease: a prospective, controlled, observer‐blind risk stratification over 10 years

Abstract

Risk of arrhythmic death is considered highest in ischemic heart disease with severe left ventricular ejection fraction (LVEF) reduction. Non-invasive testing should improve decision-making of prophylactic defibrillator (ICD) implantation. We enrolled 120 patients with ischemic heart disease and LVEF <50% and 30 control subjects without ischemic heart disease and normal LVEF. An initial assessment, a second assessment after 3years and a final follow-up comprised of pharmacological baroreflex testing (BRS), short-term spectral [low-frequency (LF) to high-frequency (HF) ratio] and long-term time-domain analysis of heart rate variability (SDNN), exercise Microvolt T-wave alternans (MTWA) and others. The median follow-up was 7·5years. Resuscitated cardiac arrest and arrhythmic death due to ventricular arrhythmias ≥240/min was observed in 18% and 15% of patients, respectively. Cardiac death was observed in 28% of patients. The incidence of arrhythmic death and resuscitated cardiac arrest was identical in patients with ischemic heart disease with LVEF <30% and ≥30%. No significant difference between subgroups with LVEF of <30%, 30-39% and ≥40% was found either. MTWA, BRS, SDNN and LF to HF ratio failed to identify patients at risk of arrhythmic death in a multiple regression model. Ischemic heart disease patients with LVEF <30% and ≥30% face the same risk of arrhythmic death. Stratification techniques fail to identify high-risk patients. Therefore, the current practice to constrain prophylactic ICDs to patients with severely reduced LVEF seems to be insufficient.