Imaging modality for left ventricular ejection fraction estimation and effect of implantable cardioverter-defibrillator on mortality in patients with heart failure

BACKGROUND Implantable cardioverter-defibrillators (ICDs) improve outcomes in patients with heart failure (HF) with left ventricular ejection fraction (LVEF) <= 35%. Less is known about whether outcomes varied between the 2 noninvasive imaging modalities used to estimate LVEF-2-dimensional echocardiography (2DE) and multigated acquisition radionuclide ventriculography (MUGA)-which use different principles (geometric vs countbased, respectively). OBJECTIVE The purpose of this study was to examine whether the effect of ICD on mortality in patients with HF and LVEF <= 35% varied on the basis of LVEF measured by 2DE or MUGA. METHODS Of the 2521 patients with HF with LVEF <= 35% in the Sudden Cardiac Death in Heart Failure Trial, 1676 (66%) were randomized to either placebo or ICD, of whom 1386 (83%) had LVEF measured by 2DE (n 5 971) or MUGA (n 5 415). Hazard ratios (HRs) and 97.5% confidence intervals (CIs) for mortality associated with ICD were estimated overall, checking for interaction, and within the 2 imaging subgroups. RESULTS Of the 1386 patients in the present analysis, all-cause mortality occurred in 23.1% (160 of 692) and 29.7% (206 of 694) of patients randomized to ICD or placebo, respectively (HR 0.77; 97.5% CI 0.61-0.97), which is consistent with that in 1676 patients in the original report. HRs (97.5% CIs) for all-cause mortality in the 2DE and MUGA subgroups were 0.79 (0.60-1.04) and 0.72 (0.461.11), respectively (P 5.693 for interaction). Similar associations were observed for cardiac and arrhythmic mortalities. CONCLUSION We found no evidence that in patients with HF and LVEF <= 35%, the effect of ICD on mortality varied by the noninvasive imaging method used to measure LVEF.