Independent Effect of Low Flow on Outcomes in Patients Undergoing Aortic Valve Replacement for Severe Aortic Stenosis

Low flow (LF; i.e., reduced left ventricular stroke volume index <35 mL/m²) can occur with severe aortic stenosis (AS). However, few studies have investigated the effects of LF on early and late outcomes after aortic valve replacement (AVR) for severe AS.

In all, 285 severe AS patients undergoing isolated AVR at Juntendo University Hospital between August 2002 and August 2015 were enrolled in the study. In this cohort, 52 patients (18%) had LF. Compared with patients with normal flow (NF) severe AS, early postoperative mortality (9.6% vs. 1.2%; P=0.006), gastrointestinal complications (5.7% vs. 0.8%; P=0.04), and the duration of the intensive care unit (ICU) stay (81.7 vs. 35.3 h; P=0.02) were increased in LF patients with severe AS. LF was an independent predictor of early mortality (Model A, odds ratio [OR] 6.81, P=0.01; Model B, OR 6.69, P=0.01) and composite complications (Model A, OR 2.44, P=0.02). In propensity score-matched comparisons, early mortality (12.8% vs. 0%; P=0.02), composite complications (28.2% vs. 10.2%; P=0.04), and duration of ICU stay (97.4 vs. 22.1 h; P=0.006) were significantly increased in LF than NF patients.

LF, as an important independent risk factor for postoperative mortality and morbidity, should be included in risk stratification and assessment in severe AS patients.