Prognostic Significance of Pre-Procedural TIMI Flow in Patients with ST-Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention: A Prospective Observational Study

Abstract

Objective: This study aimed to evaluate the prognostic significance of pre-procedural Thrombolysis in Myocardial Infarction (TIMI) flow in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI) at a tertiary cardiac care center in Peshawar, Pakistan. Methodology: A prospective observational study was conducted among 400 consecutive patients presenting with acute STEMI who underwent primary PCI between August 2025 and January 2026. Patients were categorized according to initial coronary angiography into two groups: TIMI 0 flow (complete coronary occlusion) and TIMI 1–3 flow (partial or complete antegrade coronary perfusion). Results: Among the 400 enrolled patients, the mean age was 58.0±11.0 years and 299 (74.8%) were male. Pre-procedural TIMI 0 flow was observed in 249 (62.3%) patients, whereas 151 (37.8%) demonstrated TIMI 1–3 flow. Overall in-hospital mortality was 4.2%, with a higher but statistically non-significant mortality rate among patients with TIMI 0 flow (5.6% vs. 2.0%; p=0.136). Patients presenting with TIMI 0 flow had significantly lower successful reperfusion rates (76.3% vs. 94.0%; p<0.001) and experienced higher frequencies of the no-reflow phenomenon, cardiogenic shock, heart failure, and target vessel revascularization. They also required longer hospital stays (median 5 vs. 4 days; p<0.001). Multivariable logistic regression demonstrated that although TIMI 0 flow showed a strong trend toward predicting in-hospital mortality (adjusted OR 3.66), only increasing age remained an independent statistically significant predictor of mortality. Conclusion: Pre-procedural TIMI 0 flow is strongly associated with impaired myocardial reperfusion, increased in-hospital complications, and prolonged hospitalization among patients undergoing primary PCI for STEMI. Although it was not an independent predictor of mortality in this cohort, baseline TIMI flow remains an important angiographic marker for early risk stratification and may assist clinicians in identifying patients who require closer monitoring and more intensive therapeutic management.