Objective Alcohol septal ablation (ASA) improves symptoms in hypertrophic obstructive cardiomyopathy (HOCM). We conducted a large retrospective analysis investigating gender effects on outcome after ASA.

Methods and results 1367 ASAs between 2002 and 2020 were analysed. Women (47.2%) were older (66.0 years (IQR 55.0–74.0) vs 54.0 years (IQR 45.0–62.0); p<0.0001) with more severe symptoms. The interventricular septal diameter (IVSD) was higher in men (21.0 mm (IQR 19.0–24.0) vs 20.0 mm (IQR 18.0–23.0); p<0.0001) but the IVSD indexed to body surface area was higher in women (10.9 mm/m² (IQR 9.7–12.7) vs 10.2 mm/m² (IQR 9.0–11.7); p<0.0001). Women had lower exercise-induced left ventricular outflow tract gradients (LVOTG) 1–4 days after ASA (55.0 mm Hg (IQR 30.0–109.0) vs 71.0 mm Hg (IQR 37.0–115.0); p=0.0006). There was a trend for lower resting LVOTG 1–4 days after ASA (20.0 mm Hg (IQR 12.0–37.5) vs 22.0 mm Hg (IQR 13.0–40.0); p=0.0062) and lower exercise-induced LVOTG after 6 months in women (34.0 mm Hg (IQR 21.0–70.0) vs 43.5 mm Hg (IQR 25.0–74.8); p=0.0072), but this was not statistically significant after Bonferroni correction. More women developed atrioventricular (AV) block (20.3% vs 13.3%; p=0.0005) and required a pacemaker (17.4% vs 10.4%; p=0.0002) but not a cardioverter defibrillator (9.0% vs 11.6% in men; p=n .s.). However, in multivariable regression models, there was no evidence that sex independently influenced LVOTG and the occurrence of AV block.

Conclusion Female patients with HOCM were older and had more advanced disease at the time of ASA. Women had superior short-term haemodynamic response to ASA but more often developed AV block after ASA. These results are important to consider for sex-specific counselling before ASA.