Concordant Improvements in Coronary Flow Reserve and ST-segment Resolution During Percutaneous Coronary Intervention for Acute Myocardial Infarction: a Benefit of Postconditioning

Objective: To assess the effect of ischemic postconditioning on indices of coronary microvascular function during percutaneous coronary intervention (PCI) for acute ST segment elevation myocardial infarction (STEMI).

Background: Myocardial tissue level perfusion remains suboptimal in many patients with STEMI despite restoration of antegrade flow in the epicardial coronary artery.

Methods: Twenty-four patients with an evolving anterior STEMI were randomized to undergo a previously-validated ischemic postconditioning protocol or usual care during PCI. The extent of resolution of ST segment elevation along with Doppler-tip catheter velocimetry was used as indices of myocardial reperfusion and microvascular function, respectively.

Results: Postconditioned patients exhibited a greater, and therefore more rapid, extent of ST segment resolution (postconditioning, 70% +/- 15%; control, 48% +/- 16%; P = 0.0002) by the end of the procedure. Postconditioned patients also exhibited a greater hyperemic coronary vasodilator response at the completion of the procedure (coronary flow velocity reserve, CFVR: postconditioning, 2.2 +/- 0.1; control, 1.5 +/- 0.1; P < 0.0001). The end-procedure CFVR was directly related to the extent of the ST segment resolution (r = 0.85) but inversely related to the absolute magnitude of ST segment elevation at end procedure (r = -0.76). Peak serum creatine kinase was significantly lower in postconditioned patients (postconditioning, 1,524 +/- 435 IU/l; control, 1,862 +/- 561 IU/l; P = 0.03).

Conclusions: Ischemic postconditioning, as described, can be expeditiously performed during PCI for STEMI. Concordant changes in coronary flow reserve and ST segment resolution, measures of microcirculatory function, and myocardial perfusion, were greater in postconditioned patients.