Stopping Atenolol Therapy in Severe Stable Angina Pectoris Abrupt withdrawal causes no problems in these patients

The effects of abrupt atenolol withdrawal were studied in 20 patients (group 1) admitted to hospital for coronary angiography and possible bypass surgery. Their mean age was 50 years and they all had NYHA class III or IV angina. None had hypertension or unstable angina. They took their last daily dose of atenolol 100mg on admission day and then no further doses until 6 days later. Ambulatory 24-hour ECG monitoring was performed and all patients underwent cycloergometric exercise tests on days 1 and 5. Plasma noradrenaline [norepinephrine] concentrations and urinary levels of catecholamines and vanilmandelic acid were measured on the same days. A second group consisted of 28 patients (group 2; mean age 52 years) with stable NYHA class \I or IV angina. They underwent the same exercise tests as group 1 before (test 1) and after 4 weeks' treatment (test 2) with atenolol 100 mg/day.

The only significant change seen with ambulatory ECG monitoring was a significant (p < 0.005) increase in ventricular asystoles in 10 group 1 patients. In group 1 there was a small but significant reduction in mean time to 5T depression from 6.6 on day 1 to 5.6 on day 5 (p < 0.05). Eight patients showed an unpronounced but> 10% deterioration in times to angina onset and 5T depression on day 5. In contrast to these results , group 2 patients showed marked improvements from test 1 to test 2 in mean times to angina (5.0 to 6.6 min, p < 0.05), to 5T depression (4.3 to 6.3 min, p < 00005) and to total exercise time (16.8 to 84 min, p < 0.0005). There was no significant difference in mean resting or exercise HR between group 1 patients on day 5 and group 2 patients before treatment. Similarly there were no significant changes in plasma or urinary catecholamine levels following atenolol withdrawal.

Typical withdrawal symptoms such as palpitations headache or anxiety were not reported by any patient; nor were any other serious complications .

A postwithdrawal study period of 144 hours may have been insufficient, as 96 hours after the last dose there was evidence of persistent {3-blockade. However, abrupt atenolol withdrawal in 20 patients with severe angina produced minor clinical effects consistent with the gradual disappearance of {3-blockade, rather than with the presence of sympathetic overactivity or rebound adrenergic hyperactivity . Abrupt atenolol WIthdrawal in patients with less severe or no angina may therefore carry no appreciable risk of a coronary event. Walker. P.R .. Marshall. AJ. : Farr. S. : Bauminger. B. and Walters. G.: British Heart Journal 53: 276-282 (Mar 1985)

14 INPHARMA@ 27 Apr 1985 0156_2703/ 85/ 0427-0014 / 0$01 .00/ 0 © ADIS Press