Prognostic significance of energy loss index in patients with low gradient severe aortic stenosis and preserved ejection fraction

Abstract

We hypothesized that among patients with low gradient severe aortic stenosis (LG-AS) and preserved left ventricular ejection fraction (LVEF), reclassification of AS severity as moderate by pressure recovery adjusted indexed aortic valve area (AVAi)–energy loss index (ELI)–may identify a subgroup of patients with a better outcome. In total, 379 patients with LG-AS (defined by AVAi ≤ 0.6 cm2/m2 and mean aortic pressure gradient < 40 mmHg) and preserved LVEF ≥ 50%were studied. Reclassification as moderate AS by ELI was defined as AVAi ≤ 0.6 cm2/m2 but an ELI > 0.6 cm2/m2. All-cause and cardiac mortality were studied. In total, 148 patients (39%) were reclassified as moderate AS by ELI. Reclassification as moderate AS was independently associated with absence of coronary artery disease, decreased body surface area, normal flow status, and decreased left ventricular mass index (all P < 0.05). While reclassification as moderate AS by ELI was not associated with overall mortality during follow-up, reclassification as moderate AS by ELI was associated with a significant reduction of risk of cardiac mortality after adjustment for variables of prognostic interest including aortic valve replacement as a time-dependent covariable (adjusted HR 0.44 [95% CI, 0.21–0.91]; P = 0.027). In patients with low gradient severe AS and preserved LVEF, calculation of ELI permits to reclassify almost 40% of patients as having moderate AS. These reclassified patients have a considerable reduction of risk of cardiac mortality during follow-up. Calculation of ELI may be useful for decision making in patients with low gradient severe AS and preserved ejection fraction.