Abstract 12643: Sub-Endocardial Viability Index and Survival in the HF-ACTION Trial

Abstract

Introduction: Myocardial perfusion relative to left-ventricular workload may be estimated by the sub-endocardial viability index (SVI). This can be calculated myocardial oxygen supply-demand balance, which is the ratio of diastolic to systolic pressure-time indices, i.e. [(DBP - PAWP) x (60sec/heart rate - 0.2sec)] / (SBP x 0.2sec), assuming fixed 0.2sec for systole. Low SVI indicates reduced sub-endocardial perfusion and was hypothesized to associate with negative outcomes in HFrEF patients. Methods: HF-ACTION was a randomized trial evaluating the efficacy of aerobic exercise training and usual care versus usual care in chronic HFrEF patients. SVI was calculated in HF-ACTION trial patients with complete hemodynamic data. PAWP was calculated using the Nagueh formula from echocardiographic-derived measurements ([PAWP=1.24*(E/e’) +1.9] with e’ = [(e’lateral + e’septal)/2]). The association of SVI with the combined endpoint of death or hospitalization, as well as all-cause death, was assessed. Results: Of 2331 patients in HF-ACTION, 807 had complete data. The mean SVI was 1.59 ± 0.47. The Cox proportional hazards model for the combined endpoint and all-cause death had HR of 0.66 per unit increase in SVI (p<0.00001, 95% CI 0.55-0.79) and 0.67 (p=0.04, 95% CI 0.46-0.98), respectively. Survival during 4 year follow-up was worse below the mean SVI (p=0.0073) ( Figure 1) . In 26 patients below the critical sub-endocardial ischemia SVI of 0.7, survival was worse (p=0.0013) ( Figure 2) . Conclusion: Reduced SVI, a metric of the adequacy of sub-endocardial perfusion, is associated with negative outcomes in HFrEF patients. Figure 1. Figure 2.