Thrombolysis in Myocardial Infarction (TIMI) Flow and Myocardial Blush (MB) as Predictors of Left Ventricular Ejection Fraction Improvement in Patients with Acute Myocardial Infarction with ST Segment Elevation Undergoing Primary Percutaneous Coronary Intervention

Background: Reperfusion success in ST-elevation myocardial infarction (STEMI) is often measured by macrovascular TIMI flow. However, myocardial tissue perfusion, assessed via Myocardial Blush (MB), may provide a more accurate prognosis. This study evaluates TIMI flow and MB as predictors of Left Ventricular Ejection Fraction (LVEF) improvement in STEMI patients post-Primary Percutaneous Coronary Intervention (PCI). Methods: This prospective cohort study included STEMI patients undergoing PCI. TIMI flow and MB (using QuBE software) were measured post-procedure. LVEF was evaluated at baseline and 2-month follow-up. Data were analyzed using Chi-square for Relative Risk (RR) and Cox regression for Adjusted RR. Results: High MB (QuBE ≥9 AU) was a significant independent predictor of LVEF improvement. Patients with high MB had a 1.6 times greater chance of functional recovery compared to those with low MB (RR 1.60; 95% CI 1.21–2.11; p0.05). Multivariate analysis confirmed high MB as the sole independent predictor of LVEF recovery (Adjusted RR 1.57; 95% CI 1.04–2.63; p=0.045). Conclusion: Microvascular perfusion (MB), rather than macrovascular flow (TIMI), is the primary determinant of left ventricular functional recovery post-PCI. Achieving successful reperfusion at the myocardial tissue level is critical for long-term cardiac improvement.