Immediate angioplasty compared with the administration of a thrombolytic agent followed by conservative treatment for myocardial infarction. The Mayo Coronary Care Unit and Catheterization Laboratory Groups.

BACKGROUND

Immediate angioplasty and the administration of a thrombolytic agent followed by conservative treatment are two approaches to the management of acute myocardial infarction, but these methods have not been compared prospectively.

METHODS

We enrolled 108 patients with acute myocardial infarction in a randomized trial designed to test the hypothesis that immediate angioplasty (without previous thrombolytic therapy) may result in greater myocardial salvage than the administration of a thrombolytic agent followed by conservative treatment. The primary end point was the change in the size of the perfusion defect as assessed at admission and discharge by tomographic imaging with technetium-99m sestamibi, a myocardial perfusion agent that can measure myocardium at risk and final infarct size.

RESULTS

End-point data were available for 56 patients randomly assigned to receive tissue plasminogen activator (mean [+/- SD] time to start of infusion, 232 +/- 174 minutes after the onset of chest pain) and 47 patients randomly assigned to receive angioplasty (first balloon inflation at 277 +/- 144 minutes). In the case of anterior infarction, myocardial salvage as assessed by imaging with technetium-99m sestamibi was 27 +/- 21 percent of the left ventricle for 22 patients in the thrombolysis group, as compared with 31 +/- 21 percent for 15 patients in the angioplasty group. For infarcts in all other locations, myocardial salvage was 7 +/- 13 percent for 34 patients in the thrombolysis group and 5 +/- 10 percent for 32 patients in the angioplasty group. After adjustment for infarct location, the difference in mean salvage between groups was 0 (P = 0.98), with a 95 percent confidence interval of +/- 6 percent of the left ventricle.

CONCLUSIONS

In patients with acute myocardial infarction, immediate angioplasty does not appear to result in greater myocardial salvage than the administration of a thrombolytic agent followed by conservative treatment, although a small difference between these two therapeutic approaches cannot be excluded.