Abstract 6176: Myocardial Salvage Beyond the 12-Hour Limit in Primary Angioplasty for STEMI
Background: Guidelines from the AHA/ACC limit the recommendation of primary PCI to STEMI-patients with symptoms for less than 12 hours on admission. However, 8.5– 40% of STEMI-patients have symptoms for more than 12 hours on presentation.
Objective: We evaluated left ventricular (LV) outcomes according to the 12-hour limit in primary PCI for STEMI.
Methods: Immediate primary PCI was performed in 396 patients with symptoms for 0 –72 hours on admission. Myocardial perfusion imaging (MPI) was done acutely to measure the non-perfused area at risk of infarction before PCI (% of LV myocardium). MPI was repeated 30 days after primary PCI to assess final infarct size (% of LV myocardium), salvage (% of LV myocardium salvaged), salvage index (% of area at risk salvaged), and LV ejection fraction (LVEF).
Results: Outcomes of latecomers (12–72 hours, n=55) vs. early presenters (<12 hours, n=341) are shown in Table 1⇓. In the total population, latecomers had larger final infarct size, lower LVEF, and a strong trend to reduction of salvage index (p=0.05), but salvage did not differ according to the 12-hour limit. All linear correlations of symptom duration (0 –72 hours) vs. final infarct size, salvage, salvage index, and LVEF were weak (R2-values <0.10), both in the total population and in patients with total occlusion of the infarct-related artery (TIMI-flow 0). In the TIMI 0 group, latecomers had reduction of salvage index compared with early presenters (Table 1⇓). However, 41% of latecomers had substantial salvage (>50% of area at risk) despite total occlusion of the infarct-related artery.
Conclusions: In primary PCI for STEMI, final infarct size is increased and salvage index is reduced within the time frame from 12–72 hours after onset of symptoms. However, substantial myocardial salvage is observed beyond the 12-hour limit, even when the infarct-related artery is totally occluded. Until further studied, STEMI-latecomers should be offered primary angioplasty on a liberal basis.