The effectiveness of -blockade and its influence on heart rate variability in vasovagal patients

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Abstract
The aim of this study was to assess the effectiveness of chronic medical treatment with oral propranolol and its influence on heart rate variability in patients with vasovagal syndrome. A spectral frequency domain analysis was used for the estimation of heart rate variability characteristics. Thirty-six patients, mean age 49 ± 17 years, with a history of recurrent syncope and positive tilt testing were involved in the study. All patients received oral propranolol (five patients also had a dual chamber inhibited DDI pacemaker implanted) for a mean time 12 ± 6 months. One patient complained of syncope during this follow-up. The tilt test repeated in 29 patients during follow-up was negative in 28. In 20 patients treatment was discontinued for 4 days and a new tilt test was then performed. Eleven of these 20 patients (55%) had a positive test (PP = 0.02). The ratio between the increases in the sympathetic and parasympathetic components was also higher in the vasovagal group (1.7 ± 0.7 vs 1.0 ± 0.3 respectively P = 0.01). These differences during tilt testing were eliminated after propranolol treatment. It is concluded that sympathetic activity is a predominant factor in the pathogenesis of vasovagal syndrome and that medical therapy with propranolol could be effective in vasovagal patients.

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