Effect of chronic intercurrent medication with beta-adrenoceptor blockade or calcium channel entry blockade on postoperative silent myocardial ischaemia.

Abstract

We have examined observational data from four published studies investigating the incidence of postoperative silent myocardial ischaemia (post-SMI) for the effects of chronic intercurrent therapy with beta-adrenoceptor blockade or chronic calcium channel entry blockade. A total of 453 patients underwent ambulatory ECG monitoring before and for 2 days after non-cardiac surgery; 79 patients were receiving chronic intercurrent beta-adrenoceptor blockade and 70 calcium channel entry blockade for ischaemic heart disease or arterial hypertension. Using logistic regression analysis, we defined a model for post-SMI that included four significant terms: beta-adrenoceptor blockade; calcium channel entry blockade; arterial hypertension; and vascular surgery. Using univariate regression, there was no effect of chronic beta-adrenoceptor blocking therapy on post-SMI (odds ratio 0.94 (95% confidence intervals 0.54-1.65)), but there was a higher incidence of post-SMI in patients receiving chronic calcium channel entry blocking drugs (odds ratio 1.95 (1.15-3.32); P = 0.015). There was no interaction between beta-adrenoceptor blockade and calcium channel entry blockade for postoperative SMI (odds ratio 2.48 (0.71-8.73)), but there was an interaction between beta-adrenoceptor blockade, calcium channel entry blockade, hypertension and vascular surgery (P = 0.0201). These findings are at variance with those which have shown effects of preoperative beta-adrenoceptor blockade on the incidence of post-SMI over the first 7 days after operation, and on mortality rates to 2 yr. There are no comparable data examining the effects of chronic intercurrent calcium channel entry blockade.