Temporal Trends in the Clinical Acuity of Patients with ST-Segment Elevation Myocardial Infarction

Background: Despite advances in ST-segment elevation myocardial infarction (STEMI) systems of care over the last decade, studies have shown no improvement in risk-adjusted mortality. It has been hypothesized that the population presenting to the catheterization laboratory has become sicker over time, in ways not accurately captured by current mortality models. The objective of this study was to examine changes in the clinical characteristics and in-hospital case fatality rate of the STEMI population treated with early percutaneous coronary intervention (PCI).

Methods: We conducted a retrospective analysis of a nationwide inpatient database for the period 2004-2012. All patients with a diagnosis of STEMI who underwent PCI within 24 hours of admission were identified. The primary outcome was in-hospital mortality.

Results: From 2004 to 2012 there was a consistent increase in unadjusted in-hospital mortality (3.9% in 2004 and 4.7% in 2012, odds ratio_year 1.03; 95% confidence interval 1.01-1.04). During this time there was an increase in the proportion of patients with ≥3 Elixhauser comorbidities (14.8% vs 29.0%, P_trend < .001). Intubation or cardiac arrest on presentation increased from 3.2% to 7.8% (P_trend < .001) and had a strong, independent association with mortality. After multivariable adjustment using a model that incorporated the increasing trend in intubation/cardiac arrest, mortality decreased over time (odds ratio_year 0.95; 95% confidence interval 0.94-0.97).

Conclusions: During a period that corresponds to improvement in STEMI quality of care, risk-adjusted in-hospital mortality declined. An increase in comorbidities, and more importantly in the proportion of patients presenting with extreme-risk features, may explain the overall "null" effect regarding in-hospital mortality despite improvements in timely reperfusion.