Changes in cardiac output determined by continuous-wave Doppler echocardiography during propafenone or mexiletine...

Antiarrhythmic drugs may induce congestive heart failure in patients with malignant ventricular arrhythmias and depressed left ventricular (LV) function. Whether Doppler echocardiography can detect drug-induced depression in LV function was assessed. Continuous-wave Doppler measurements of ascending aortic blood flow velocity were obtained in 16 patients while not receiving antiarrhythmic drugs on 2 consecutive days to assess day-to-day variability, as well as while receiving maximally tolerated oral doses of mexiletine (11 patients) and propafenone (9 patients). While receiving propafenone, a drug with moderate negative inotropic activity, peak flow velocity declined by 9 +/- 8% (p less than 0.05), the flow velocity integral (termed stroke distance, representing stroke volume) declined by 8 +/- 11% (p less than 0.10), the rate-corrected stroke distance declined by 9 +/- 8% (p less than 0.02) and the minute distance, representing cardiac output, declined by 10 +/- 12% (p less than 0.05). In contrast, while receiving mexiletine, a drug with minimal negative inotropic activity, none of these parameters changed significantly. Five of 9 patients (56%) treated with propafenone showed a decline in rate-corrected stroke distance exceeding the 95% confidence limit of day-to-day variability, which was +/- 13 percent. Two of these 5 patients developed clinical signs of congestive heart failure. Continuous-wave Doppler echocardiography can detect antiarrhythmic drug-induced LV dysfunction and may be used to anticipate the development of significant clinically overt congestive heart failure.