Effect of intervention timing on one-year mortality in elderly non-ST-segment elevation myocardial infarction patients

Background The best timing for early invasive therapy in non-ST-segment elevation myocardial infarction (NSTEMI) patients remains controversial. We sought to determine the optimal timing of early catheterization in order to improve long-term outcomes in elderly (>65 years old) patients with NSTEMI. Methods Using data from the CRUSADE registry linked to Medicare claims, we evaluated the association of early catheterization within the first 24 h or earlier time cut-points of NSTEMI presentation with long-term mortality among older Medicare beneficiaries. Results Of 15 575 NSTEMI patients from 398 CRUSADE hospitals (2003-2006), 3880 (24.9%) received early (≤12 h) catheterization. Compared with those undergoing later catheterization, patients treated early were younger and had less comorbid illness. Relative to those treated later, patients receiving early catheterization had similar 1-year all-cause mortality (11.8% vs 11.9%, P = 0.90). Using on- vs off-hour presentation as an instrumental variable, balancing potential measured and unmeasured confounders, early and later catheterization patients had nonsignificant differences in 1-year mortality (+5.6% [-11.5%, +22.7%]). Similar results were observed in clinically relevant subgroups, such as age (< or ≥75 years), gender, diabetes status, Global Registry of Acute Coronary Events score (< or ≥140), presence of heart failure, and sensitivity analyses of alternative definitions of early catheterization (≤6 and ≤24 h). Conclusions Among older NSTEMI patients, we found that <24 h or earlier (neither <6 nor 12 h) of catheterization timing were not significantly associated with differences in long-term mortality.