ABSTRACTThe goal of this study was to verify whether myocardial protection could be achieved via the intracoronary administration of propranolol in patients undergoing percutaneous transluminal coronary angioplasty (PTCA). Accordingly, 21 patients undergoing PTCA were randomly assigned to receive either intracoronary placebo (group A, n = 10) or intracoronary propranolol (group B, n = 11). Three balloon inflations (i.e., coronary artery occlusions) were performed in each patient. Inflations I and II (maximum duration 60 sec) served as control occlusions. Inflation III (maximum duration 120 sec) was performed either after intracoronary administration of saline (2 ml) or propranolol (1.1 + 0.2 mg). The following electrocardiographic index of myocardial ischemic injury were measured: (1) time to the development of ST segment elevation equal to 0.1 mV and (2) magnitude of ST segment elevation after 60 sec of coronary artery occlusion. Both indexes did not differ significantly between the groups during inflations I and LI. In group A the time to development of ST segment elevation of 0.1 mV remained unchanged between the second and third occlusions (25 + 5 and 26 ± 4 sec during inflations II and III, respectively). In group B subselective injection of propranolol into the affected coronary artery significantly prolonged the time to ST segment elevation of 0. 1 mV from 19 + 4 sec (inflation II) to 53 ± 9 sec (inflation III; p <.001). Administration of placebo did not change the magnitude of ST segment elevation 60 sec after coronary artery occlusion between the second and third occlusion in group A (0. 16 + 0.02 and 0. 18 ± 0.03 mV, respectively). In group B, after intracoronary administration of propranolol, ST segment elevation 60 sec after occlusion decreased significantly from 0.23 0.06 mV (inflation II) to 0.12 ± 0.04 mV (inflation III; p <.005). There were no significant differences in heart rate and mean aortic pressure between groups A and B during inflations I, II, and III. In conclusion, our results suggest that (1) repetitive episodes of transient coronary artery occlusion are associated with similar degrees of myocardial ischemic injury, (2) intracoronary propranolol significantly reduces the electrocardiographic indexes of myocardial ischemic injury, and (3) the myocardial protection afforded by intracoronary propranolol is most likely mediated by a regional effect of the drug.