An analysis was performed of the Mayo Clinic randomized trial of direct percutaneous transluminal coronary angioplasty and tissue-type plasminogen activator (t-PA) to determine the time required to achieve reperfusion with direct coronary angioplasty. Because patients in the Mayo trial assigned to t-PA did not undergo protocol coronary angiography, reperfusion rates from the Thrombolysis in Myocardial Infarction (TIMI) I trial in which patients underwent coronary angiography 30, 60 and 90 minutes after thrombolytic therapy were used for comparison. TIMI perfusion grade 2 or 3 flow in the infarct artery was considered to represent reperfusion after thrombolysis. In the 56 patients assigned to t-PA, the mean time from randomization to initiation of the t-PA infusion was 20 minutes. Twenty minutes were therefore added to the previously reported 30-, 60- and 90-minute reperfusion rates to express these in terms of time from randomization (50, 80 and 110 minutes). In the 48 patients who had direct angioplasty, the mean time from randomization to arrival in the cardiac catheterization laboratory was 45 minutes; it took a mean of 6 additional minutes for patients to be prepared and draped and arterial access obtained, and a mean of 27 additional minutes to complete angiography and achieve reperfusion. At 50, 80 and 110 minutes after randomization, the reperfusion rates for direct coronary angioplasty were 12, 54 and 83%, similar to previously reported TIMI reperfusion rates with t-PA (24, 57 and 71%, respectively, p = NS) but significantly greater at 80 and 110 minutes than was reported for streptokinase (8, 23 and 31%, respectively, p = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)