Impact of Total Ischemic Time on the Recovery of Regional Wall Motion Abnormality after STEMI in the Modern Reperfusion Era

Background. Total ischemic time (TIT) is an important factor for predicting mortality among patients with ST-segment elevation myocardial infarction (STEMI). However, the correlation between TIT and the extent of wall motion abnormality has not been well studied. Therefore, we investigated changes in the wall motion score index (WMSI) value based on TIT in STEMI patients who underwent primary percutaneous coronary intervention (PCI) and subsequent transthoracic echocardiography. Methods. STEMI patients who underwent primary PCI and follow-up coronary angiography were analyzed after the exclusion of cases of in-stent restenosis (ISR). WMSI values were calculated by dividing the sum of scores by the number of segments visualized. Results. A total of 189 patients underwent primary PCI for STEMI, and 151 had no ISR with a median follow-up of 12.3 months. TIT was 180 (117-369) minutes in a subset of 151 patients (mean age of 62 years; 76% male). Among patients without ISR, 109 (72%) demonstrated a decrease in the WMSI value during the follow-up period. The WMSI values of patients with TITs of 180 minutes or less were significantly decreased relative to those among patients with TITs of greater than 180 minutes (p=0.020). Among patients with TITs of 180 minutes or less, the TIT was significantly shorter among those with a reduction in the WMSI value than among those with an increase in the WMSI value (106 [81-124] vs. 133 [100-151] minutes; p=0.018). TIT was an independent predictor for a reduction in the WMSI value among these patients (adjusted hazard ratio: 0.976 (0.957-0.995); p=0.016). Conclusions. In the modern reperfusion era of STEMI, patients with TITs of 180 minutes or less experienced a significant degree of recovery from regional wall motion abnormalities.