Annual Trends in Total Ischemic Time and One-Year Fatalities: The Paradox of STEMI Network Performance Assessment

Abstract

This study is aimed at assessing trends and relations between total ischemic time, the major quality measure of systemic delay, and case-fatality at the population or patient level in response to growing cardiovascular risk and a constant need to shorten the time to treatment in ST-segment elevation myocardial infarction (STEMI). Data from a prospective nationwide registry of STEMI patients admitted between 2006 and 2013 who were treated with primary percutaneous coronary intervention (PCI) were analyzed. Total ischemic time was calculated as the time from the onset of symptoms to primary PCI and was determined as individual and annual. The primary end-point was one-year, all-cause case-fatality. Among the total 70,093 analyzed patients, temporal trends showed significant decrease in total ischemic time (268 vs. 230 minutes, p < 0.001), a worsening of the risk profile and an increase in one-year case-fatality (7.1% vs. 10.8%, p < 0.001). In the multivariate analysis, longer individual total ischemic time was a risk factor for higher mortality (HR 1.024, 95%CI 1.015–1.034, p < 0.001) and remained significant after adjustment for the year of admission. An inverse relation was observed for the median annual time (HR 0.992, 95%CI 0.989–0.994, p < 0.001). Thus, the observed increasing annual trends in case-fatality cannot directly measure the quality of STEMI network performance.