Novel Echocardiographic Index for Risk Stratification of Ventricular Arrhythmias and Mortality Based on Right Ventricular Function

ABSTRACT Background Right ventricular (RV) dysfunction is independently predictive of sudden cardiac death. This study aimed to compare the performance of different risk stratification methods for death and appropriate implantable cardioverter‐defibrillator (ICD) therapy using echocardiography and cardiac magnetic resonance imaging (CMR) to quantify RV function. Methods Consecutive patients undergoing ICD implantations who had completed both preprocedural echocardiography and CMR were retrospectively enrolled. Patients with channelopathies or arrhythmogenic right ventricular disease were excluded. The RV fractional area change (RVFAC) and estimated pulmonary artery pressure (EPAP) were calculated from echocardiography. The contraction pressure index (CPI) was defined as the quotient of the RVFAC divided by the EPAP. Both metrics were used to predict the composite endpoint of death and an appropriate ICD therapy. RV dysfunction was defined by either RVFAC < 35% or RV ejection fraction (RVEF) < 45%. Results In total, 88 patients (60.4 ± 14.7 years, 61 males) including 15 with ischemic cardiomyopathy were retrospectively enrolled. Forty‐two patients received ICDs as secondary prevention. The mean RVFAC, CPI, and RVEF were 35.9% ± 9.22%, 1.4% ± 0.7%/mmHg, and 39.5% ± 14.4%, respectively. Regarding the composite endpoint, the best cut‐off value of the CPI was 1.59 (specificity 0.45, sensitivity 0.96, ROC‐AUC 0.68). The hazard ratio of a low RVFAC was 3.28 (95% CI: 1.39–7.77, p = 0.007, concordance = 0.622), a low CPI, 14.2 (95% CI: 1.91–104.9, p = 0.010, c = 0.665), and a low RVEF, 3.44 (95% CI: 1.17–10.1, p = 0.003, c = 0.620). Conclusion Both CMR‐derived RVEF and the echocardiographic CPI predicted appropriate ICD therapy and death. The CPI may provide superior risk stratification.