Objective: Women have lower flow, i.e., lower stroke volume (SV) than men even after adjustment for body size (SVi). Using the same cut-off value for defining low flow in both women and men may contribute to the described higher prevalence of paradoxical low-flow low-gradient (PLFLG) aortic stenosis (AS) in women. Using sex-specific thresholds for low flow is suggested, but the influence on the prevalence of PLFLG AS is unknown.                                 

Methods: Retrospective data from 614 patients pre-transcatheter aortic valve implantation (TAVI) was used. Paradoxical low gradient AS was defined as combined aortic valve area (AVA) ≤1.0 cm² and mean aortic gradient <40 mmHg with preserved left ventricular (LV) ejection fraction. PLFLG AS was present in patients having low-flow. Low flow was defined as SVi ≤35ml/m² for both sexes and sex-specific low flow as SVi ≤32ml/m² in women and ≤40ml/m² in men. Distribution of SVi in men and women was analyzed. Prevalence of PLFLG AS using sex-specific thresholds for low SVi was compared to using the same thresholds in both sexes.

Results:  Paradoxical low-gradient AS was present in 113 patients, 44% male with a mean age of 82.4 ± 6.2 years. The mean SVi was 37±9ml/m², 92% of patients presented in NYHA class III and 3.5% in NYHA class IV, 74% were hypertensive, 50% in atrial fibrillation and coronary heart disease was present in 62%. The mean calcium score (Agatston) was 2290±1353. Distribution of SVi in men and women shows significantly lower SVi in women compared to men (P<0.01) (Figure). PLFLG AS was present in 49% (n=42) (42.9%, n=15 male and 52.9%, n= 27 female) and sex-specific PLFLG AS in 42% (n=36) (62.9%, n=22 male and 27.5%, n= 14 female) (P<0.01).

Conclusions: Using sex specific thresholds for defining low flow contributes to lower prevalence of PLFLG AS, particularly in women.