Comparing invasive and noninvasive management strategies for acute myocardial infarction using administrative databases

Purpose The aim of this study was to compare outcomes after acute myocardial infarction between regions with low and high catheterization access. Methods Observational study using administrative databases of patients with acute myocardial infarction in provinces with low (Ontario) and high (Quebec and British Colombia) access to invasive cardiac procedures (ICP, n = 141 718). Using instrumental variables to control for confounding, effectiveness of treatment was measured on 1-year mortality among marginal patients (patients for whom treatment is discretionary and highly dependent on access to ICP). Results The ICP approach was associated with overall decreased mortality (−11%, 95% CI −13% to −8%) with statistically significant reductions in low-access regions (−16%, 95% CI −21% to −10%). High-access regions (QC −8%, 95% CI −19% to 4%) (BC −2%, 95% CI −12% to 7%) exhibited smaller marginal benefits. Conclusion The invasive approach benefits all marginal patients, with greater benefits in regions of lower access, indicating a threshold of availability above which further mortality benefits are negligible.