Restoration of Microcirculatory Patency after Myocardial Infarction: Results of Current Coronary Interventional Strategies and Techniques

We sought to evaluate the restoration of microcirculatory patency after primary percutaneous coronary intervention (PCI) in an unselected cohort of patients at a tertiary center. We retrospectively evaluated distributions of the Thrombolysis in Myocardial Infarction (TIMI) myocardial perfusion grade (TMPG) and the myocardial blush grade (MBG) in all primary PCI procedures performed at our institution during 2008. We defined optimal microvascular perfusion as simultaneous TMPG 3 and MBG 3 at procedure's end. Ninety-nine patients (mean age, 61.5 ± 12.7 yr; 64 men) underwent primary PCI. Microvascular perfusion was optimal in 69 patients (69.7%) and was associated with lower peaks of enzymes than those occurring in patients with suboptimal perfusion. When optimal microvascular perfusion was achieved, early spontaneous recanalization was more frequently observed, as expressed by a higher frequency of TIMI-3 flow (34.8% vs 10%; P=0.006), TMPG 3 (26% vs 3.3%; P=0.004), and MBG 3 (24.6% vs 3.3%; P=0.004) on the initial angiogram before primary PCI. A higher frequency of MBG 3 (50% vs 20%; P=0.005) was seen after initial recanalization in patients with optimal microvascular perfusion. Multiple regression analysis showed that MBG after initial recanalization and the use of drug-eluting stents were associated with optimal perfusion. Despite successful recanalization of the culprit coronary artery, optimal microvascular perfusion was achieved in less than 75% of the patients. Restoration of the microvasculature was associated with smaller infarcts. Procedure-related variables associated with suboptimal perfusion were unlikely to be causative.