Women undergoing transcatheter aortic valve replacement (TAVR) for severe aortic stenosis have lower 1-year mortality than men, even though their 30-day rates of vascular complications and major bleeding are worse, according to a report published online Feb. 23 in Annals of Internal Medicine.
“These findings for TAVR directly contrast with the abundant literature on aortic valve surgery, in which female sex has been shown to be an established risk factor for adverse prognosis,” said Dr. Susheel Kodali of Columbia University, New York and New York–Presbyterian Hospital, and his associates.
Previous studies assessing sex-specific differences in outcomes after TAVR, which have been small in size and limited to the experience at only one or two medical centers, have yielded conflicting results. Dr. Kodali and his associates examined sex-specific outcomes in what they described as the largest such study to date – a secondary analysis of data from a large clinical trial and a patient registry, involving 2,559 patients treated at 25 sites in the United States, Canada, and Germany. Their analysis involved nearly equal numbers of women (1,220) and men (1,339).
One-year unadjusted all-cause mortality was significantly lower for women (19.0%) than men (25.9%), for an HR of 0.72. In a further analysis that adjusted for numerous potential confounding factors, female sex remained independently associated with lower 1-year mortality, also with an HR of 0.72. Women also had a lower rate of rehospitalization at 1 year (15.8% vs. 18.9%; HR, 0.82). In contrast, stroke incidence did not differ significantly between women and men (5.2% vs. 4.5%; HR, 1.16).
Mortality was lower for women regardless of access route: 17.4% (vs. 24.0% in men) for the transfemoral approach and 20.8% (vs. 28.8% in men) for the transapical approach, the investigators said (Ann Intern Med. 2016 Feb 23. doi: 10.7326/M15-0121).
This mortality benefit occurred despite the fact that women had higher rates of vascular complications (17.3% vs. 10.0%) and of major bleeding (10.5% vs. 7.7%) at 30 days.
Although this study was not designed to elucidate why women have lower mortality than men following TAVR, there are several plausible reasons. First, men in this study had a greater burden of comorbid conditions than women.
Second, women had smaller annulus sizes and greater ejection fractions than men at baseline, and they also had less aortic regurgitation after undergoing the procedure. “These echocardiographic differences may [represent] better preoperative preservation of contractility and superior hemodynamics in women after the procedure,” Dr. Kodali and his associates said.
Third, previous studies have reported that after undergoing surgical aortic valve replacement, women with aortic stenosis have less cardiac fibrosis and more rapid left-ventricular remodeling than men do. “These salutary benefits may extend to women having TAVR” as well, the investigators added.