Oral disopyramide therapy for obstructive hypertrophic cardiomyopathy

Area of Science:

• Cardiology
• Pharmacology

Background:

• Obstructive hypertrophic cardiomyopathy (HC) is a significant cause of morbidity.
• Current treatments for HC include medications and surgery, with varying efficacy and side effects.

Purpose of the Study:

• To evaluate the efficacy of oral disopyramide in reducing left ventricular outflow tract (LVOT) gradients in patients with obstructive HC.
• To assess the long-term effects and safety of disopyramide treatment in this patient population.

Main Methods:

• Seven patients with obstructive HC received oral disopyramide.
• LVOT gradients were measured using echocardiography before, during, and after disopyramide treatment.
• Disopyramide serum levels were monitored concurrently with gradient measurements.

Main Results:

• Acute disopyramide administration significantly reduced mean LVOT gradients from 64 to 14 mm Hg (p < 0.0001).
• Chronic treatment maintained gradient reduction (mean 13 mm Hg after 23 days), with gradients returning to baseline upon withdrawal and decreasing again upon rechallenge.
• High disopyramide serum levels correlated with lower LVOT gradients (r = -0.77, p < 0.0001), with a 49% reduction observed even at low therapeutic levels.
• Four patients experienced symptomatic improvement and were maintained on disopyramide for over a year.

Conclusions:

• Oral disopyramide effectively and acutely decreases obstruction in patients with obstructive HC.
• Disopyramide provides sustained pharmacologic control of obstruction and is a potential alternative to other treatments like adrenergic blockers, calcium antagonists, or surgery.