In patients with acute ST-elevation myocardial infarction (STEMI) who are undergoing percutaneous coronary intervention, current guidelines for reperfusion therapy recommend a door-to-balloon (DTB) time of less than 90 minutes. Considerable effort has focused on reducing DTB time with the assumption that a reduction in DTB time translates into a significant reduction in mortality; however, the clinical impact of this effort has not been evaluated. Therefore, our objective was to determine whether a decline in DTB time in patients with STEMI was associated with an improvement in clinical outcomes.
We assessed the yearly trend in DTB time for 8771 patients with STEMI who were undergoing primary percutaneous coronary intervention from 2003 to 2008 as part of the Blue Cross Blue Shield of Michigan Cardiovascular Consortium and correlated it with trends in in-hospital mortality. Patients were stratified according to risk of death using a mortality model to evaluate whether patient risk factors affect the relationship between DTB time and mortality.
Median DTB time decreased each year from 113 minutes in 2003 to 76 minutes in 2008 (P < .001), and the percentage of patients who were revascularized with a DTB time of less than 90 minutes increased from 28.5% in 2003 to 67.2% in 2008 (P < .001). In-hospital mortality remained unchanged at 4.10% in 2003, 4.02% in 2004, 4.40% in 2005, 4.42% in 2006, 4.73% in 2007, and 3.62% in 2008 (P = .69). After the differences in baseline characteristics were adjusted for, there was no difference in the standardized mortality ratios (SMRs) across the study period (SMR, 1.00; 95% confidence interval [CI], 0.74-1.26 in 2003 compared with SMR, 0.95; 95% CI, 0.77-1.13 in 2008).
There has been a dramatic reduction in median DTB time and increased compliance with the related national guideline. Despite these improvements, in-hospital mortality was unchanged over the study period. Our results suggest that a successful implementation of efforts to reduce DTB time has not resulted in the expected survival benefit.