CHANGES IN CARDIAC-OUTPUT DETERMINED BY CONTINUOUS-WAVE DOPPLER ECHOCARDIOGRAPHY DURING PROPAFENONE OR MEXILETINE DRUG-TESTING

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 < 0.05), the flow velocity integral (termed stroke distance, representing stroke volume) declined by 8 ± 11% (p < 0.10), the rate-corrected stroke distance declined by 9 ± 8% (p < 0.02) and the minute distance, representing cardiac output, declined by 10 ± 12% (p < 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. © 1990.