Factors relating to the beta blocker withdrawal syndrome.

Clinical studies were performed with groups of patients with ischaemic heart disease, patients with hyperthyroidism, and normal subjects, to investigate the possibility of a beta blocker withdrawal syndrome, by measurments of heart rate under conditions of increased sympathetic drive provided by standing with vasodilatation or by Valsalva's manoeuvre. A rebound increase in heart rate to levels significantly higher than the control heart rate off treatment was observed 2-5 days after stopping one or more weeks' treatment with dl-propranolol (160 mg/day), atenolol (200 mg/day), acebutolol (400 mg/day) or oxprenolol (160 mg/day).