Malignant vasovagal syncope: a randomised trial of metoprolol and clonidine.

OBJECTIVE To evaluate the efficacy of head up tilt guided treatment with metoprolol and clonidine in preventing the recurrence of syncope in patients with malignant vasovagal syncope. PATIENTS 20 patients (9 men and 11 women, mean age 33 (SD 17), range 14 to 62 years) with severe symptoms. DESIGN Randomised double blind crossover trial; efficacy was assessed by head up tilt testing. RESULTS Metoprolol was more effective than clonidine in abolishing syncope (19/20 v 1/20, P < 0.001) but clonidine showed some beneficial effects on time to syncope and severity of hypotension in 12 patients. During an average follow up of 15 (3) months there was a significant reduction in the recurrence of symptoms compared with the previous year in patients who had tilt up guided treatment (18 metoprolol, 1 clonidine). CONCLUSIONS Treatment guided by head up tilting is a reliable method of treating patients with malignant vasovagal syndrome. Metoprolol was an effective long term treatment for preventing syncope. High doses were more effective and a careful dose titration period helped to minimise withdrawal symptoms and side effects.