Original paper
Factors affecting microvascular flow in patients with myocardial infarction treated with percutaneous coronary intervention

Background: Abnormal myocardial flow is related to higher in-hospital and late mortality. The prognosis of patients with myocardial infarction is also worsened by the presence of no-reflow. Therefore, the aim of the study was to identify independent predictors of abnormal microvascular flow and flow decrease or no-reflow phenomenon in patients with ST-segment elevation myocardial infarction (STEMI) treated with percutaneous coronary intervention (PCI). Methods: The analysis included consecutive patients with STEMI treated with PCI (direct stenting or stenting after balloon predilatation). The analysis excluded patients with pulmonary edema and cardiogenic shock. Results: 217 out of 300 consecutive patients were included in the analysis. 110 patients underwent direct stenting angioplasty while 107 patients had stenting after balloon predilatation. In the univariate analysis the most relevant factor determining TMPG 0-1 (TIMI Myocardial Perfusion Grade) was the angioplasty of left descending artery (OR=2.15, 95% CI 1.03-4.51) and, subsequently, an anterior infarction (OR=2.12, 95% CI 1.01-4.43). Moreover, longer pain duration to beginning of the procedure and older age increased TMPG 0-1 occurrence risk by 1.49 per one hour and 1.06 per one year, respectively. The multivariate analysis disclosed that age was the independent predictor of TMPG 0-1 (per 1 year OR=1.04, 95% CI 1.00-1.08). The univariate analysis showed that diabetes was associated with approximately 6-fold higher risk of flow decrease or no-reflow (OR=6.10, 95% CI 2.22-16.80). The risk ratio of flow decrease or no-reflow per 1 mm of lesion or stent length was 1.20 and 1.09, respectively. In addition, patients’ age (OR=1.07, 95% CI 1.02-1.12) and percent stenosis after PCI in infarction-related segment (OR=1.04, 95% CI 1.01-1.08) were the independent factors of increased risk. The multivariate analysis showed that the independent predictors of flow decrease or no-reflow were: diabetes (OR=8.09, 95% CI 2.3-28.3), lesion length (per 1 mm OR=1.26, 95% CI 1.08-1.49) and age (per 1 year OR=1.06, 95% CI 1.00-1.13). Direct stenting was not related to TMPG 0-1, flow decrease or no-reflow. Conclusions: In patients with acute myocardial infarction treated with PCI factors influencing microvascular flow and no-reflow occurrence can be identified.