IMPACT OF ISCHEMIA TIME ON REGIONAL WALL MOTION RECOVERY AND LEFT VENTRICULAR EJECTION FRACTION IN PATIENTS UNDERGOING PRIMARY PERCUTANEOUS CORONARY INTERVENTION FOR STEMI

Abstract

Background: In acute ST-segment elevation myocardial infarction (STEMI), immediate mechanical reperfusion via primary percutaneous coronary intervention (PCI) is critical to limit myocardial injury. However, the time window from symptom onset to reperfusion—Total Ischemic Time (TIT)—directly impacts myocardial salvage. This study compares post-primary PCI changes in the Wall Motion Score Index (WMSI) and Left Ventricular Ejection Fraction (LVEF) between patients presenting early (3 hours) versus those presenting late (> 3 hours) from symptom onset.

Methods: A prospective comparative study was conducted over 12 months at the Faisalabad Institute of Cardiology. One hundred and sixty patients with first-onset STEMI successfully treated with primary PCI were divided into two equal groups: Group A (TIT < 3 hours, n=80) and Group B (TIT >3 hours, n=80). Serial transthoracic echocardiography (TTE) was pierformed at 24 hours and 2 months post-reperfusion to evaluate WMSI and LVEF.

Results: The mean age of the cohort was 62.5 +- 11.5 years, with a baseline male predominance (72.5%). Risk profiles and baseline lab parameters (except CK-MB) were evenly matched across both cohorts (p > 0.05). At the 24-hour baseline assessment, no significant differences were observed between Group A and Group B for WMSI (1.35 \pm 0.21 vs. 1.39 +_0.25, p = 0.734) or LVEF (43.40+- 7.31% vs. 42.51%+_ 7.73%, p = 0.64). However, at the 2-month follow-up, Group A demonstrated significantly greater regional wall motion recovery (WMSI: 1.09 +_ 0.23 vs. 1.28 +_ 0.28, p = 0.02) and significantly higher global systolic function (LVEF: 48.43% +_ 7.41% vs. 43.61\% +_ 7.92%, p = 0.02).

Conclusion: A total ischemic time of less than 3 hours is associated with a highly significant recovery of regional wall motion abnormalities and preservation of global left ventricular ejection fraction. Healthcare systems must prioritize reducing pre-hospital and system delays to preserve long-term cardiac performance.