The effect of propranolol, prindolol, practolol and verapamil versus placebo on exercise induced tachycardia in patients with ventricular preexcitation.

Propranolol, prindolol, practolol and verapamil have been given orally in a fixed dose to subjects with preexcitation syndrome in a cross over study. The effect on exercise induced tachycardia, prevention of tachyarrhythmias and normalization of heart rate after exercise was investigated. Propranolol, practolol and prindolol significantly (p less than 0.01-0.05) reduced the heart rate at rest and during exercise and favourably influenced the normalization of the heart rate after exercise. The effect on effort tolerance (work done till the submaximal heart rate was reached) was significantly better after propranolol (versus prindolol and verapamil) and practolol (versus verapamil) only. Verapamil showed a consistent effect only given intravenously in paroxysmal tachycardia while in the majority of patients there was no difference between oral verapamil and placebo.