National door-to-balloon times for patients undergoing primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction have improved and the percentage of patients meeting the guideline recommendation of 90 minutes or less has increased, but in-hospital and short-term mortality has remained unchanged, according to a study published Sept. 4 in the New England Journal of Medicine .

The study looked at 96,738 patients undergoing PCI for ST-segment elevation myocardial infarction at 515 hospitals enrolled in the CathPCI Registry®. Results showed that median door-to-balloon times decreased from 83 minutes from July 2005 – June 2006, to 67 minutes from July 2008 – June 2009 (P<0.001). Further, the percentage of patients who met the guideline recommendation of 90 minutes or less increased from 59.7 percent to 83.1 percent (P<0.001).

However, “despite improvements in door-to-balloon times, there was no significant overall change in unadjusted in-hospital mortality (4.8 percent in 2005-2006 and 4.7 percent in 2008-2009, P=0.43 for trend) or in risk-adjusted in-hospital mortality (5.0 percent in 2005-2006 and 4.7 percent in 2008-2009, P=0.34), nor was a significant difference observed in unadjusted 30-day mortality (P=0.64).”

The authors note that data regarding the relationship between door-to-balloon time and mortality have been inconsistent, and that their data “suggest that further efforts to reduce door-to-balloon time may not reduce mortality.” They explain that door-to-balloon time is merely one component of total ischemic time, and “as door-to-balloon time is reduced, it becomes a smaller fraction of total ischemic time, making the time before arrival at a hospital a more important factor.”

Moving forward, the authors note that “additional strategies are needed to reduce in-hospital mortality in this population.” Strategies include “increasing patients’ awareness of symptoms onset to treatment, and shortening the transfer time between medical facilities. In addition, improving both in-hospital care and post-discharge care remain key targets for enhancing long-term outcomes after ST-segment elevation myocardial infarction.”

Commenting on the study, ACC President John Gordon Harold, MD, MACC, notes “the ACC stands by the guidelines on which door-to-balloon is based. The study shows in-hospital mortality rates have not significantly changed with the reduction in door-to-balloon time, but short-term mortality is not the only goal of door-to-balloon. We are also interested in recovery and quality of life after heart attack. Time is muscle, and the sooner treatment begins, the less muscle is damaged, which preserves functionality of the heart and quality of life.”

“The ACC agrees with the authors’ conclusion that we should continue to look for ways to bring mortality down further,” Harold adds. “We have already been extremely successful in reducing mortality to a very low level, but a variety of factors contribute to mortality. It will be impossible to reduce it to zero, but there's no doubt that reduced door-to-balloon time contributes significantly to better outcomes.”

Keywords: Registries, Myocardial Infarction, Hospital Mortality, Quality of Life, New England, Percutaneous Coronary Intervention