Abstract
Background: Although guidelines recommend invasive management for non-ST-elevation myocardial infarction (NSTEMI), there is considerable variability in the application of these recommendations across different hospitals, reflecting a lack of standardized clinical pathways and highlighting ongoing uncertainty in real-world practice. We sought to describe site-level variability in the use and timing of invasive angiography for NSTEMI and their association with in-hospital outcomes. Methods: Using NCDR Chest Pain-MI registry data (2019-2024), the rates and timing of invasive coronary angiography, if any, were characterized among patients with NSTEMI. Hierarchical logistic regression models were created to describe hospital-level variability in management using median odds ratios (MORs), adjusted for patient and site characteristics. Inverse probability weighting was used to estimate the association between treatment strategy and in-hospital outcomes. Results: We included 287,275 patients with Type-1 NSTEMI from 541 hospitals (age 67.6±13.3 years, 36.4% women). Invasive coronary angiography was performed in 87.1%, of whom 56.9% within 24 hours. Among those treated invasively, 66.1% received percutaneous coronary intervention. Older patients with more comorbidities were paradoxically more likely to receive conservative management or delayed intervention (>24 hours). Site-level variability for invasive strategy (vs. conservative) was large [MOR 2.85 (2.64-3.10)], as was early invasive treatment [MOR 1.67 (1.62-1.74)], particularly on weekends/holidays [MOR 1.89 (1.81-1.98)]. The use of any invasive strategy was associated with lower in-hospital mortality versus conservative management [weighted OR 0.36 (0.31-0.42)]. This finding was consistent across all baseline risk categories (P-interaction <0.001). Conclusions: Patients with Type-1 NSTEMI and higher-risk clinical profiles were not consistently prioritized to undergo early invasive management with substantial variability across hospitals. Invasive management was associated with lower in-hospital mortality compared with conservative treatment. Future randomized studies in the modern PCI era are needed to confirm our findings, and identify which patients benefit most and when intervention should occur.