Beta-blockers may have limited additional benefit in patients taking angiotensin-converting enzyme inhibitors (ACEI)/angiotensin II receptor blockers (ARB) and/or statins after acute myocardial infarction (AMI). In fact, the mortality rates were similar in the patients who adhered only to ACEI/ARBs and statins and in the patients who adhered to all three therapies post AMI, according to a study published Sept. 18 in the Journal of the American College of Cardiology.

Led by Maarit J. Korhonen, LicSci (Pharm), PhD, et al., the study used the Centers for Medicare and Medicaid Services Medicare Chronic Condition Data Warehouse to identify 90,869 patients (median age, 77 years) who had a prescription for all three therapies (ACEI/ARB, statins and beta-blockers) and survived 180 days or more after being hospitalized for AMI between 2008 and 2010. The authors measured therapy adherence by proportion of days covered (PDC) of the 180 days after being discharged, classifying adherent as 80 percent PDC and non-adherent as less than 80 percent PDC. Mortality follow-up covered the 18 months following the 180-day post-discharge period.

Researchers found that more than half of patients (51.5 percent) were non-adherent to one or more preventive therapies. Of the non-adherent group, 31 percent did not take ACEI/ARBs, 24 percent did not take beta-blockers and 23 percent did not take statins. Additionally, one-tenth of the total study population (n = 9,617) died during follow-up. The highest mortality rate was seen among patients who were non-adherent to all three therapies (hazard ratio [HR], 1.65; 95 percent confidence interval [CI], 1.54-1.76), followed by those who only took beta-blockers (HR, 1.32; 95 percent CI, 1.2-1.44).

"Clinical uncertainties exist as to the clinical impact of adherence to some therapies versus all three in the long-term. In clinical practice, this is a particularly challenging issue for older adults with multiple morbidities and polypharmacy," state the authors. "We found markedly higher mortality risk for being adherent to beta-blockers only among patients with diabetes or dementia than among patients without these conditions."

The authors note that future studies should address race-specific questions and reasons for discontinuing medication, particularly whether it was the decision of the physician, patient or caretaker. This additional research would help provide information on the risks and benefits associated with various combinations of guideline-recommended preventive therapies in post AMI patients who also have specific comorbidities (heart failure, diabetes or dementia). 

"It's safe to say that adherence to medications post-MI is in dire need of an infusion of 'stickiness,'" note Eric D. Peterson, MD, MPH, FACC, and Ann Marie Navar, MD, PhD. In a related editorial comment, they commend the study authors on raising a provocative hypothesis, yet underline the unlikeliness that a large randomized trial would ever occur to confirm the results. "Given these medications are now generic and low-cost, designing a trial to determine the safety of stopping one of these medications is unlikely," they state.

Instead, Peterson and Navar explore patient education tools, electronic reminders and more, emphasizing the importance of physician-patient conversations and the impact compelling messaging would have on overall behavioral change. "The field of medicine should learn from their colleagues in marketing, behavioral economics, and social science to identify which levers are most effective for improving patient medication adhere, and then test the impact of moving those levers in large outcome trials."

Keywords: United States, Angiotensin-Converting Enzyme Inhibitors, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Comorbidity, Secondary Prevention, Economics, Behavioral, Research Personnel, Confidence Intervals, Centers for Medicare and Medicaid Services, U.S., Adrenergic beta-Antagonists, Medicare, Angiotensin Receptor Antagonists, Myocardial Infarction, Heart Failure, Diabetes Mellitus, Polypharmacy, Dementia, Risk Assessment

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