Impact of Early (≤24 h) Versus Delayed (>24 h) Intervention in Patients With Non-ST Segment Elevation Myocardial Infarction: An Observational Study of 20,882 Patients From the London Heart Attack Group.

Introduction: We aimed to investigate the optimal timing of invasive coronary angiography and subsequent intervention in non-ST-segment elevation acute myocardial infarction (NSTEMI) patients.

Methods: We examined the impact of early (≤24 h) versus delayed (>24 h) intervention in a large observational cohort of 20,882 consecutive NSTEMI patients treated with PCI between 2005 and 2015 at 8 tertiary cardiac centers in London (UK) using Cox-regression analysis and propensity matching.

Results: Mean age was 64.5 ± 12.7 years and 26.1% were females. A quarter (27.6%), were treated within 24 h. Patients treated within 24 h were slightly younger (62.8 ± 12.8 vs. 65.2 ± 12.6, p < 0.001), most commonly male (76% vs. 72.9%, p < 0.001) and were more frequently ventilated (2.3% vs. 1.4%, p < 0.001) and in cardiogenic shock (3.6% vs. 1.4%, p < 0.001) with dynamic changes on their ECG (84.5% vs. 76.1% p < 0.001). At a median follow up of 4.2 years (interquartile range 1.8 to 7) 17.7% of patients had died. Estimated 5-year survival in patients treated within 24 h was 84.6% vs. 81% for those treated >24 h following their presentation (p < 0.001). This survival benefit remained following adjustment for confounders; HR 1.11 (95%CI 1.003 to 1.23, p = 0.046). In the propensity matched cohort of 4356 patients in each group, there remained a trend for higher survival in the early intervention group (p = 0.061).

Conclusions: Notwithstanding the limitations of the retrospective design, this real-world cohort of NSTEMI patients suggests that an early intervention (≤24 h) may improve mid-term survival.