Effects of Aortic Valve Replacement on Severe Aortic Stenosis and Preserved Systolic Function: Systematic Review and Network Meta-analysis

The survival benefits of aortic valve replacement (AVR) in the different flow-gradient states of severe aortic stenosis (AS) is not known. A comprehensive search in PubMed/MEDLINE, Embase, Cochrane Library, CNKI and OpenGrey were conducted to identify studies that investigated the prognosis of severe AS (effective orifice area <= 1.0 cm(2)) and left ventricular ejection fraction >= 50%. Severe AS was stratified by mean pressure gradient [threshold of 40 mmHg; high-gradient (HG) and low-gradient (LG)] and stroke volume index [threshold of 35 ml/m(2); normal-flow (NL) and low-flow (LF)]. Network meta-analysis was conducted to assess all-cause mortality among each AS sub-type with rate ratio (RR) reported. The effects of AVR on prognosis were examined using network meta-regression. In the pooled analysis (15 studies and 9,737 patients), LF states (both HG and LG) were associated with increased mortality rate (LFLG: RR 1.88; 95% CI: 1.43-2.46; LFHG: RR: 1.77; 95% CI: 1.16-2.70) compared to moderate AS; and NF states in both HG and LG had similar prognosis as moderate AS (NFLG: RR 1.11; 95% CI: 0.81-1.53; NFHG: RR 1.16; 95% CI: 0.82-1.64). AVR conferred different survival benefits: it was most effective in NFHG (RRwith AVR/RRwithout AVR: 0.43; 95% CI: 0.22-0.82) and least in LFLG (RRwith AVR/ RRwithout AVR: 1.19; 95% CI: 0.74-1.94).