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

We have examined observational data from four published studies investigati ng the incidence of postoperative silent myocardial ischaemia (post-SMI) fo r the effects of chronic intercurrent therapy with beta-adrenoceptor blocka de or chronic calcium channel entry blockade. A total of 453 patients under went ambulatory ECG monitoring before and for 2 days after non-cardiac surg ery; 79 patients were receiving chronic intercurrent beta-adrenoceptor bloc kade and 70 calcium channel entry blockade for ischaemic heart disease or a rterial hypertension. Using logistic regression analysis, we defined a mode l for post-SMI that included four significant terms: beta-adrenoceptor bloc kade; calcium channel entry blockade; arterial hypertension; and vascular s urgery. Using univariate regression, there was no effect of chronic beta-ad renoceptor blocking therapy on post-SMI (odds ratio 0.94 (95% confidence in tervals 0.54-1.65)), but there was a higher incidence of post-SMI in patien ts 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 b lockade and calcium channel entry blockade for postoperative SMI (odds rati o 2.48 (0.71-8.73)), but there was an interaction between beta-adrenoceptor blockade, calcium channel entry blockade, hypertension and vascular surger y (P=0.0201). These findings are at variance with those which have shown ef fects of preoperative beta-adrenoceptor blockade on the incidence of post-S MI over the first 7 days after operation, and on mortality rates to 2 yr. T here are no comparable data examining the effects of chronic intercurrent c alcium channel entry blockade.