[Antiarrhythmic action of beta-blocking agent in patients with mitral valve prolapse having premature ventricular contractions].

To investigate the origin and evaluate the effect of one of the most potent beta blocker, carteolol, on premature ventricular contractions (PVCs) in patients with mitral valve prolapse (MVP), 21 patients (35 +/- 12 years; mean +/- SD) including 10 with PVCs were studied by simultaneous electrocardiography and echocardiography before and after intravenous injection of carteolol. In all 21 MVP patients including 10 MVP patients with PVCs, carteolol (6 micrograms/kg/2 min, i.v.) caused significant decrease in systolic and diastolic blood pressures and in heart rate. Carteolol markedly (25% or more) reduced frequency of PVCs in four of the 10 patients, but no significant changes in five, and PVCs were increased in frequency in the remaining one. However, in all 21 MVP patients, carteolol did not change left ventricular end-diastolic and end-systolic dimensions, and the degree of MVP nor mitral regurgitant areas evaluated by color Doppler echocardiography. These results were exactly the same as those of the patients with PVCs. In conclusion, intravenous injection of beta-blocker, carteolol, reduced PVCs in 40% of the MVP patients with PVCs, but this antiarrhythmic action is not related to the degree of mitral valve prolapse, or mitral regurgitation evaluated by Doppler method.