Reduced baseline left ventricular function may explain female survival benefit after TAVI

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A new study indicates that the apparent survival benefit after transcatheter aortic valve implantation (TAVI) that women have over men relates to the baseline left ventricular ejection fraction (LVEF). In this study, the survival benefit for women was only observed in patients with preprocedural LVEF ≤50%.

Writing in EuroIntervention, Timm Bauer (University Clinic Giessen, Department of Cardiology, Giessen, Germany) and others report that there is “convincing evidence” that female patients have a lower mortality rate after TAVI than do men, but add “the reasons for this gender-specific differences in outcome are not well understood”. Furthermore, Bauer et al observe that LVEF is a “strong independent predictor” of early and mid-term mortality after TAVI and “affects men and women differently”. Therefore—given that the relationship between gender, LVEF, and post-TAVI prognosis “remains unclear”—they retrospectively reviewed gender-specific differences and one-year outcomes with regard to LVEF within a large, contemporary registry.

Of 15,616 patients in the GARY (German Society for Thoracic and Cardiovascular Surgery) registry, 8,456 were women and 16.4% of these had a baseline LVEF >50% (compared with 17.6% of men). Hospital mortality was similar between women and men (5.1% vs. 5.2%). However, one-year mortality was significantly lower in women—18.1% vs. 22.6% (p<0.0001). Furthermore, in a multivariate analysis, female gender was associated with lower one-year mortality after TAVI.

When grouped by baseline LVEF, there were no significant differences in gender-specific mortality among patients with baseline LVEF >50%. But, the authors comment, one-year mortality was significantly higher in men than in women among patients with LVEF 30–50% (25.7% vs. 21%, respectively; p<0.001) and among those with LVEF <30% (37.6% vs. 26.2%; p<0.001). They add: “In patients with LVEF <30% and with prior myocardial infarction one-year, mortality was similar; whereas in patients with LVEF <30% and without prior myocardial infarction, one-year mortality was significantly lower in women.” Furthermore, testing for interaction confirmed a statistically significant relationship between gender, LVEF, and prognosis in TAVI patients. “This is an important finding since a substantial proportion of TAVI patients have a reduced LVEF,” Bauer et al comment.

Reviewing why reduced LVEF appears to affect men and women differently, the authors observe that gender has been shown to influence cardiac remodelling and fibrosis in patients with severe aortic stenosis. They also note that “women develop a more concentric form of left ventricular hypertrophy and less left ventricular dilation than men” and “interstitial fibrosis is less pronounced in women”. Bauer et al conclude that “baseline left ventricular function is a decisive factor for the gender-specific differences in mortality after TAVI”, nothing that this may relate to “different post-procedural cardiac remodelling”.