Infarct size and myocardial salvage after primary angioplasty in patients presenting with symptoms for <12 h vs. 12-72 h

Primary angioplasty for ST-segment elevation myocardial infarction (STEMI) is recommended only if symptom duration is < 12 h. We evaluated final infarct size (FIS) and myocardial salvage in early presenters (< 12 h) vs. late presenters (12-72 h) undergoing primary angioplasty. Myocardial perfusion imaging (MPI) was performed acutely to assess area at risk (AAR) before angioplasty and repeated after 30 days to assess FIS (% of LV myocardium), salvage index (% non-infarcted AAR), and left ventricular ejection fraction (LVEF). Late presenters (n = 55) compared with early presenters (n = 341) had larger median FIS [14% (inter-quartile range 3-30) vs. 7% (2-18), P = 0.005], lower salvage index [53% (27-89) vs. 69% (45-91), P = 0.05], and lower LVEF [48% (44-58%) vs. 53% (47-59), P = 0.04]. However, FIS, salvage index, and LVEF correlated weakly with symptom duration (R-2-values < 0.10). In patients with TIMI-flow 0 (n = 247), late presenters had lower salvage index than early presenters [44% (23-73) vs. 57% (42-86), P = 0.03], but substantial salvage (> 50% of AAR) was observed in 41% of late presenters despite total infarct-artery occlusion. FIS is larger in late presenters (> 12 h) than early presenters after primary angioplasty for STEMI. However, substantial myocardial salvage can be obtained beyond the 12 h limit, even when the infarct-related artery is totally occluded.