Evaluation of Flow After Transcatheter Aortic Valve Replacement in Patients With Low-Flow Aortic Stenosis: A Secondary Analysis of the PARTNER Randomized Clinical Trial.

Abstract

Low-flow (LF) severe aortic stenosis (AS) is an independent predictor of mortality in patients undergoing aortic valve replacement (AVR). Little is known about improvement in flow after AVR and its effects on survival. To determine whether higher flow (left-ventricular stroke volume index [LVSVI]) after transcatheter AVR (TAVR) would indicate better clinical outcomes in this at-risk population. A substudy analysis of data from the Placement of Aortic Transcatheter Valves (PARTNER) randomized clinical trial and continued-access registry was conducted. A total of 984 participants with evaluable echocardiograms and baseline LF AS (LVSVI ≤35 mL/m2) were included. The trial was conducted at 26 sites in the United States and Canada. Patients were stratified after TAVR into tertiles by discharge LVSVI status (severe low flow [SLF], moderate low flow [MLF], and normal flow [(NF]). The present study was conducted from May 11, 2007, to January 9, 2012, with data analysis performed from April 25, 2014, to January 21, 2016. The primary end point was all-cause mortality at 1 year. Baseline characteristics of 984 patients with LF AS included mean (SD) age, 84 (7) years; 582 (59.1%) men; mean Society of Thoracic Surgeons (STS) score, 11.4% (4.0%); and mean LVSVI, 27.6 (5.0) mL/m2. The discharge LVSVI values by group were SLF, 23.1 (3.5) mL/m2; MLF, 31.7 (2.2) mL/m2; and NF, 43.1 (7.0). All-cause mortality at 1 year was SLF, 26.5%; MLF, 20.1%; and NF, 19.6% (P = .045). Mean LVSVI normalized by 6 months in the MLF (35.9 [9.3] mL/m2) and NF (38.8 [11.1] mL/m2) groups, but remained low in the SLF group at 6 months and 1 year (31.4 [8.4] and 33.0 [8.3] mL/m2], respectively) (P < .001 for all groups). Reported as multivariate hazard ratio, mortality at 1 year was higher in the SLF group compared with the other groups (1.61; 95% CI, 1.17-2.23; P = .004). In addition to SLF, sex (1.59; 95% CI, 1.18-2.13; P = .002), presence of atrial fibrillation (1.41; 95% CI, 1.06-1.87; P = .02), STS score (1.03; 95% CI, 1.01-1.06; P = .02), presence of moderate or severe mitral regurgitation at discharge (1.65; 95% CI, 1.21-2.26; P = .001), pre-TAVR mean transvalvular gradient (0.98; 95% CI, 0.97-0.99; P = .004), and effective orifice area index (1.87; 95% CI, 1.09-3.19; P = .02) were independent predictors of 1-year mortality. Severe LF at discharge is associated with an increased risk of mortality following TAVR in patients with severe AS and preexisting LF. The identification of remedial causes of persistent LF after TAVR may represent an opportunity to improve the outcome of these patients. clinicaltrials.gov Identifier: NCT00530894.