The effect of disopyramide therapy on functional capacity improvement in patients with obstructive hypertrophic cardiomyopathy

Background: Hypertrophic cardiomyopathy (HCM) is characterized by left ventricular outflow tract obstruction (LVOTO), leading to symptoms and adverse outcomes. Disopyramide, with its negative inotropic effects, is commonly used to reduce LVOTO in obstructive HCM (HOCM). This study evaluates the impact of disopyramide on functional capacity in HOCM patients.

Methods: Symptomatic HOCM patients evaluated between October 2021 and May 2024 were divided into two groups: those receiving disopyramide and those treated with beta-blockers or calcium channel blockers due to disopyramide unavailability. A treatment response was defined as at least a 1-stage improvement in NYHA class. Clinical and laboratory data, including NT-proBNP levels and LVOT gradient, were compared between groups.

Results: A total of 127 patients were included (median age 54.0 years, 58.2% male). 79% of patients were in NYHA class 2. After follow-up, 62% of the disopyramide group (the mean follow-up duration was 15.2 months, and the mean daily dose was 395 mg) showed at least a 1-stage improvement in functional capacity, compared to 26% in the control group. Disopyramide use and presence of extent LGE were independent predictors of functional improvement. Despite functional gains, there was no difference in overall clinical outcomes between the groups. Disopyramide-related side effects were minimal, and no patients discontinued due to QT prolongation.

Conclusions: Disopyramide significantly improved functional capacity in HOCM patients, with 62% achieving a 1-stage NYHA improvement compared to 26% in the control group. These results highlight the need for better accessibility to disopyramide in regions where it is difficult to obtain.