Better Door-to-Balloon Times Do Not Translate to Lower Mortality in STEMI Patients

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While door-to-balloon (D2B) times have decreased on a national scale in patients with ST-segment elevation myocardial infarction (STEMI), in-hospital and 30-day mortality rates have remained largely static in this population, according to data from a registry analysis published in the September 5, 2013 issue of the New England Journal of Medicine.

Researchers led by Daniel S. Menees, MD, of the University of Michigan (Ann Arbor, MI), looked at 95,007 STEMI patients admitted for primary PCI as part of the National Cardiovascular Data Registry’s CATHPCI Registry from July 2005 through June 2009. Patients transferred from another facility for primary PCI or those who were undergoing nonemergency PCI were excluded.

Stents were implanted in the vast majority (89.3%) of patients, with DES use peaking at 76.8% in 2005-2006 and falling to 37.4% in 2007-2008. Femoral access was the consistent route of choice in 98.0% of cases in 2005-2006 and 98.5% in 2008-2009.

D2B Times Go Down, Mortality Does Not

Median D2B times decreased each year over the study period, from 83 minutes in 2005-2006 to 67 minutes in 2008-2009 (P < 0.001). However, this improvement did not translate to a meaningful decrease in in-hospital mortality, which remained steady over time (4.8% in 2005-2006 to 4.7% in 2008-2009; P = 0.43).

In addition, the percentage of patients with median D2B times of 90 minutes or less increased from 59.7% to 83.1% over the length of the study (P < 0.001), while the percentage with a D2B time of more than 90 minutes decreased from 40.3% to 16.9% (P < 0;001). Nevertheless, overall mortality remained unchanged, including high-risk subgroups such as those over age 75, with anterior MI, or with cardiogenic shock (table 1), despite D2B times that declined over the course of the study.

Table 1. D2B Times and Mortality in High-Risk Subgroups

After adjusting for variables in the NCDR model, the researchers identified no association between the annual reduction in D2B time and mortality (OR for a 10-min reduction in D2B time, 1.04; 95% CI 0.99-1.09; P = 0.17).

In a subgroup analysis using a linked Medicare dataset of 26,202 patients, D2B times declined significantly from a median of 88 minutes in 2005 to 68 minutes in 2009 (P < 0.001), yet there was almost no change in unadjusted 30-day mortality over the same time period (9.7% to 9.8%; P = 0.64).

According to the authors, the study results reflect the major focus that has been placed on achieving lower D2B times for STEMI patients in the United States, with more than 80% of patients undergoing primary PCI for STEMI meeting the goal of 90 minutes or less by 2009.

Important Questions Raised

“Despite these improvements. . . . overall unadjusted and risk-adjusted in-hospital mortality remained virtually unchanged,” they observe. “Our findings raise questions about the role of [D2B] time as a principal focus for performance measurement and public reporting.”

Dr. Menees and colleagues note that the push for shorter D2B times has been driven by the concept that a shorter interval between ischemia and reperfusion results in improved myocardial salvage and, thus, presumably better clinical outcomes.

However, D2B time “is one component of total ischemic time,” the researchers point out. “As [D2B] time is reduced, it becomes a smaller fraction of total ischemic time, making the time before arrival at a hospital a more important factor. Therefore, efforts with potential to improve outcomes may include increasing patients’ awareness of symptoms, reducing the interval from the time of symptom onset to treatment, and shortening the transfer time between medical facilities.”

In an accompanying Perspective article, Eric R. Bates, MD, of the University of Michigan Health System (Ann Arbor, MI), and Alice K. Jacobs, MD, of Boston University Medical Center (Boston, MI), agree that D2B times are only part of the overall picture of effective STEMI treatment.

“Although door-to-balloon time remains important, it’s time to turn our attention to the further development of systems that address the continuum of STEMI care, from symptom onset through return to the community,” they write.

Time is Muscle

In a prepared statement, American College of Cardiology (ACC) President John G. Harold, MD, MACC, maintained that striving for shorter D2B times is still important.

“By providing real tools to help hospitals improve teamwork and communication in order to reach the guideline-recommended time-to-treatment of 90 minutes or less, we have not only helped close a clear gap in care, but saved patient lives in the process,” he said, adding that “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,” Dr. Harold said, adding that there is no doubt that reduced door-to-balloon time contributes significantly to better outcomes.

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1. Menees DS, Peterson ED, Wang Y, et al. Door-to-balloon time and mortality among patients undergoing primary PCI. N Engl J Med. 2013;369:901-909.

2. Bates ER, Jacobs AK. Time to treatment in patients with STEMI [Perspective]. N Engl J Med. 2013; 369:889-892.

Disclosures:

• Drs. Menees, Bates, and Jacobs report no relevant conflicts of interest.

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