Predictors of Impaired Reperfusion in ST-Elevation Myocardial Infarction Treated with Primary PCI: Preliminary Results from COMA.NET Project

<b>Background:</b> The no-reflow phenomenon remains a frequent and clinically significant complication in patients with ST-segment elevation myocardial infarction (STEMI) despite advances in primary percutaneous coronary intervention (pPCI). Its determinants are multifactorial and not fully established. This study aimed to identify independent predictors of impaired reperfusion after pPCI. <b>Methods:</b> In this prospective study, 100 consecutive STEMI patients treated with successful pPCI in a high-volume tertiary center were analyzed. Impaired reperfusion was defined as ST-segment resolution < 50% or final TIMI flow < 3. Clinical characteristics, laboratory findings, including platelet reactivity, and detailed angiographic and procedural parameters were collected. Independent predictors were evaluated using multivariable logistic regression. Thirty-day and twelve-month mortality were assessed with Kaplan-Meier analysis. <b>Results:</b> Impaired reperfusion occurred in 39% of patients. Compared with the normal reperfusion group, patients with noreflow were older, had lower left ventricular ejection fraction, eGFR, longer ischemia times, and more often presented with anterior STEMI. Platelet reactivity did not differ between groups. Four variables independently predicted impaired reperfusion: longer pain-to-balloon time (OR 1.05 per 10 min, 95% CI 1.02-1.07; <i>p</i> < 0.001), anterior myocardial infarction (OR 5.05, 95% CI 1.14-22.38; <i>p</i> = 0.03), use of predilatation (OR 7.66, 95% CI 1.78-32.9; <i>p</i> = 0.006), and higher Killip-Kimball class (OR 7.69, 95% CI 1.88-31.38; <i>p</i> = 0.004). Impaired reperfusion was associated with significantly higher mortality at 30 days (1.6% vs. 10%; <i>p</i> < 0.001) and 12 months (3.2% vs. 25.6%; <i>p</i> < 0.001). <b>Conclusions:</b> In this prospective STEMI cohort, impaired reperfusion was frequent and strongly associated with adverse short- and long-term outcomes. Ischemia duration, infarct location, hemodynamic status, and procedural strategy were key determinants of noreflow, while platelet reactivity showed no significant association.