P2707Optimal timing of invasive strategy in stable non-ST-segment elevation myocardial infarction: impact of immediate intervention

Abstract

Background: The optimal timing of intervention in non-ST-elevation myocardial infarction (NSTEMI) remains controversial. We sought to assess impact of immediate percutaneous coronary intervention (PCI) and optimal PCI timing for stable NSTEMI. Methods: A total of 6,134 NSTEMI patients undergoing PCI from the Korea Acute Myocardial Infarction Registry were divided into group 1 (immediate PCI within 4 hours, n=1,132) and group 2 (deferred PCI after 4 hours, n=5,002). Patients with recurrent or refractory ischemia, systolic blood pressure <90 mmHg, Killip class ≥3, ventricular arrhythmia, cardiac arrest, or mechanical complications were excluded. Propensity-matched 12-month clinical outcome was compared between the groups and according to time to PCI. Results: In all patients and propensity-matched cohort (n=1,131 in each group), group 1 had higher peak troponin level, higher rate of pre-PCI Thrombolysis In Myocardial Infarction (TIMI) grade 0 or 1, higher use of glycoprotein IIb/IIIa inhibitor, and lower use of unfractionated heparin and nitrates. In all patients, 12- month rates of MI and death/MI were higher in group 1. No differences were observed in 12-month death and major adverse cardiac events (MACE: composite of death, MI, target-vessel revascularization, and coronary artery bypass graft surgery). In the propensity-matched cohort, no significant differences were observed in 12-month rates of death, MI, death/MI or MACE. However, group 1 had less major bleeding (0.8% vs. 3.0%, p=0.024) and shorter hospital stay. In the propensity-matched cohort, the effect of PCI on 12-month outcome showed a Ushaped relationship with longer time to PCI: rates of MI and death/MI according to time to PCI (≤4 hours, 4-12 hours, 12-24 hours, 24-72 hours, >72 hours after arrival) were 2.7%, 1.3%, 1.1%, 1.9%, 2.2% and 6.5%, 4.2%, 3.9%, 5.2%, 6.1%, respectively. PCI 4-12 hours and 12-24 hours after arrival was associated with lower risk of 12-month MI (hazard ratio [HR]: 0.49, 95% confidence interval [CI]: 0.25 to 0.93, p=0.03 and HR: 0.40, 95% CI: 0.22 to 0.72, p=0.002) and death/MI (HR: 0.64, 95% CI: 0.44 to 0.93, p=0.02 and HR: 0.60, 95% CI: 0.43 to 0.84, p=0.003), respectively. Conclusions: Immediate PCI for stable NSTEMI did not confer an advantage with respect to hard clinical endpoints at 12 months. PCI within 4-24 hours after arrival was associated with lower risk of adverse events.