To study the effect of oral disopyramide therapy on left ventricular function, a subject of some controversy, we obtained first-pass radionuclide ventriculograms with a multicrystal gamma camera in 19 patients with or without therapy. Our findings demonstrated that disopyramide causes deterioration in left ventricular function in patients with abnormal ejection fractions. This effect is rarely recognized clinically and occurs despite safe therapeutic serum levels.
