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Oral disopyramide therapy for obstructive hypertrophic cardiomyopathy
1Division of Cardiology, St. Luke's-Roosevelt Hospital Center, New York, New York 10019.
Insights
Disopyramide effectively reduces obstructive hypertrophic cardiomyopathy (HC) gradients. This medication offers sustained pharmacologic control, improving symptoms and serving as a viable treatment alternative.
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.
Abstract:
Seven patients with obstructive hypertrophic cardiomyopathy (HC) were treated with oral disopyramide. Left ventricular outflow tract gradients were estimated using either Doppler or M-mode echocardiography. Gradients were measured before treatment, after acute and chronic dosing, after washout and after rechallenge. Disopyramide serum levels were measured at the time of echocardiography. With the first dose, mean outflow gradient decreased from 64 to 14 mm Hg (p less than 0.0001). This decrease in gradient was still present after long-term oral treatment 23 days later, with a mean gradient of 13 mm Hg (p less than 0.001). After withdrawal from the drug, gradient returned to the pretreatment value, 79 mm Hg. After rechallenge, the gradient once again declined to 30 mm Hg (p less than 0.001). High disopyramide serum levels correlated with lower outflow tract gradients, r = -0.77 (p less than 0.0001). Even at low therapeutic drug levels, there was a 49% reduction in outflow tract gradient. Four patients were symptomatically improved and have been maintained on disopyramide for greater than 1 year. In symptomatic patients, disopyramide acutely decreases obstruction and also provides sustained pharmacologic control of obstruction. Disopyramide should be considered as a good alternative to treatment with adrenergic blockers, calcium antagonists or surgery.