Adherence to Guideline-Based Acute MI Therapies Has Prolonged Impact on Mortality Rates

The administration of guideline-based therapies for patients hospitalized with acute MI results in an early survival benefit that is sustained and enlarged over time, translating into a substantial gain in life expectancy, according to the results of a new study.

In an analysis of long-term data from the Cooperative Cardiovascular Project, survival for recipients and nonrecipients of these guideline-based therapies, which included aspirin and beta-blockers within 48 hours of admission, “diverged early after admission and continued to diverge during 17-year follow-up,” state Emily Bucholz (Boston Children’s Hospital, Boston, MA), and colleagues.

Published online May 16, 2016, in the Journal of the American College of Cardiology, the analysis includes 147,429 Medicare patients eligible for one of the guideline-based admission therapies—aspirin, beta-blockers, and acute reperfusion therapy, either with PCI or fibrinolytics. In addition, for eligible patients, the investigators analyzed long-term mortality among those who had a door-to-balloon time ≤ 90 minutes and a door-to-needle time ≤ 30 minutes.

While the five admission therapies and timing-based guidelines are derived from clinical trials in acute MI patients, these trials often enroll younger, healthier patients than the general MI population, explain the researchers. Moreover, few trials have assessed long-term survival with these therapies. 

Treatment with aspirin within the first 48 hours of hospitalization was associated with a significant reduction in mortality at 30 days compared with no aspirin, and the survival benefit was maintained until 5 years. The survival benefit of receiving a beta-blocker within 48 hours of hospitalization and undergoing acute reperfusion therapy within 24 hours of hospitalization were also associated with a significant reduction in mortality throughout the 17-year follow-up period.

The researchers say that those who received any of the five guideline-recommended therapies had significantly longer crude life expectancies than those not treated. The difference in life expectancy persisted after adjusting for patient and hospital characteristics, although the benefit was diminished.

After adjustment, treatment with aspirin, beta-blockers, and acute reperfusion therapy was associated with 0.65, 0.45, and 0.90 years of life saved among the eligible patients. Regarding the timing guidelines, patients treated with a door-to-balloon time ≤ 90 minutes gained 0.98 years of life compared with those treated outside the benchmark. For door-to-needle benchmarks, those within the 30-minute window gained 0.52 years of life compared with those with a door-to-needle greater than 30 minutes.

“This study strengthens the case for why rapid and early delivery of acute MI admission guidelines is important and highlights the magnitude of progress made in improving the quality of care for patients with acute MI in the United States,” write Bucholz and colleagues.   

Thomas Gaziano, MD (Brigham and Women’s Hospital, Boston, MA), who wrote an editorial accompanying the study, notes that the results of landmark clinical trials have not always translated into the expected benefit in the general population. One of the reasons is that it can take up to 6 years from the publication of a large randomized trial to when the treatment is incorporated into the guidelines and up to 17 years before that treatment is accepted into clinical practice.

“Although rates of appropriate use of medications for acute myocardial infarction have significantly improved over time, institutional organization has limited healthcare facilities from achieving the full benefits of the most time-sensitive therapies, such as percutaneous coronary interventions and administration of thrombolytics,” writes Gaziano.

Outside the United States, improving guideline-based therapy for the management of acute MI would likely have the greatest impact, says Gaziano. Today, as Bucholz and colleagues point out, the rate of adherence to aspirin and beta-blockers guidelines approach 99% and approximately 95% of patients are treated within the guideline-recommended door-to-balloon times of less than 90 minutes. In low- and middle-income countries, adhering to the therapies, particularly timely PCI, could have an immediate and long-term impact on cardiovascular mortality, according to Gaziano.

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