Abstract 6183: When Door-to-Balloon Time Becomes Key for Myocardial Salvage
Background Prompt reperfusion improves prognosis in patients with ST-segment elevation myocardial infarction (STEMI). Although current AHA guidelines target door-to-balloon (D2B) time <90 min regardless of symptom-to-door (S2D) delays, the impact of D2B time on myocardial salvage among patients with varying S2D times remains unclear.
Methods The BARI score was adapted to quantify the angiographic area at risk (AR) in 184 subjects with first STEMI admitted for primary percutaneous coronary intervention (PCI). Contrast-enhanced magnetic resonance was performed acutely to measure infarct size. The AR and infarct size were compared and a myocardial salvage index (MCardiology Department. Thorax InstituteSI), expressed as %AR, was computed as the proportion of the area at risk that spared necrosis.
Results In subjects with patent (TIMI 2/3, n=27) infarct related artery (IRA) MSI did not change over time (< or > 5 hours, 59 ± 35% vs 62 ± 34 %AR, respectively). On the contrary, among patients with TIMI 0/1, MSI decreased as symptom-to-balloon (S2B) time increased up to 5 hours (fig 1A⇓). Median [interquartile range] D2B was 70 min [53– 80] for <90 min and 132 [105–214] for the >90 min group. Achieving D2B time < 90 min was associated to a significant reduction in MSI only in patients presenting within the first hour of symptoms (fig 1B⇓).
Conclusions: IRA patency prior to PCI is associated with significant myocardial salvage irrespective of time to treatment. In patients with occluded IRA myocardial salvage is negligible beyond 5 hours of symptom onset. Importantly, the benefit of achieving a D2B time <90 min can only be proven in patients that present within the first hour of symptom onset.