Sex-related Differences in the Association Between Septal Wall Thickness and Survival

Background: In many conditions characterised by septal hypertrophy, females have been shown to have worse outcomes compared to males. In clinical practice and research, similar cutoff points for septal hypertrophy are still used for both sexes. Here, we explore the association between different cutoff points for septal hypertrophy and survival in relation to sex. Methods and results: We performed a retrospective analysis of consecutive patients undergoing echocardiography between March 2010 and February 2021 in a large tertiary referral centre. A total of 70,965 individuals were included. Over a mean follow-up period of 59.1 +/- 37 months, 9631 (25 %) males and 8429 (26 %) females died. When the same cutoff point for septal hypertrophy was used for both sexes, females had worse prognosis than males. The impact of septal hypotrophy on survival became statistically significant at a lower threshold in females compared to males: 11.1 mm (HR 1.13, CI 95 %:1.03-1.23, p = 0.01) vs 13.1 mm (HR 1.21, CI 95 %: 1.12-1.32, p < 0.001). However, when indexed wall thickness was used, the cutoff points were 6 mm/body surface area (BSA) (HR 1.08, CI 95 %: 1-1.18, p = 0.04) and 6.2 mm/BSA (HR 1.07, CI 95 %: 1-1.15, p = 0.05) for females and males, respectively. Conclusions: Septal hypertrophy is associated with increased mortality at a lower threshold in females than in males. This may account for the worse prognosis reported in females in many conditions characterised by septal hypertrophy. Applying a lower absolute value or using indexed measurements may facilitate early diagnosis and improve prognostication in females.