Impact of vessel size on distal embolization, myocardial perfusion and clinical outcome in patients undergoing primary angioplasty for ST-segment elevation myocardial infarction

Background: Mounting interest has emerged on the role of distal embolization as a major explanation of poor myocardial perfusion among patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary angioplasty. The aim of the current study was to evaluate the relationship between vessel size, distal embolization, myocardial perfusion and clinical outcome in patients with STEMI treated by primary angioplasty. Methods: Our population is represented by 1969 patients with STEMI undergoing primary stenting from 1997 to 2002. All clinical, angiographic, and follow-up data were prospectively collected. Results: Vessel size was linearly associated with gender, diabetes, anterior infarction location, shorter time-delay, the rate of stenting and glycoprotein IIb-IIIa inhibitors. Small vessel size was associated with poor perfusion, despite lower rates of distal embolization. These data were confirmed after correction for confounding factors. The higher risk profile and poor myocardial perfusion contribute to explain the worse outcome observed in patients with smaller vessel size. Conclusions: This study shows that in patients undergoing primary angioplasty for STEMI, small vessel size is associated with poor myocardial perfusion, despite less distal embolization, that contributes to explain the worse outcome observed among patients with small infarct related arteries.