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Secondary prevention treatments may benefit patients with MI, nonobstructive coronary arteries
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Patients with MI but nonobstructive coronary arteries experienced long-term benefits from treatments, including statins and ACE inhibitors/angiotensin receptor blockers, and positive effects from beta-blockers, according to a study in Circulation.
MI with nonobstructive coronary arteries is seen in 5% to 10% of patients with acute MI, most of whom are younger women, according to the study background.
“The present study is the first study to evaluate the association between commonly used secondary prevention treatments and long-term outcome in a large cohort of unselected patients with [MI with nonobstructive coronary arteries],” Bertil Lindahl, MD, PhD, professor of cardiology at Uppsala University in Sweden, and colleagues wrote.
Patient treatments
Researchers analyzed data from 9,136 patients (mean age, 66 years; 61% women) with MI with nonobstructive coronary arteries who were alive 30 days after discharge from July 2003 to June 2013. At discharge, 84.5% were recommended statin therapy, 83.4% were taking beta-blockers, 66.4% were taking dual antiplatelet therapy and 64.1% were prescribed ACE inhibitors/angiotensin receptor blockers.
Major adverse cardiac events, which included hospitalization for MI, all-cause mortality, ischemic stroke and HF, were the primary endpoint. Secondary endpoints were CV mortality, hospitalization for a bleeding event, and any of the individual primary endpoints. Patients taking most treatments were followed up for adverse events after 30 days until death or Dec. 31, 2013 (mean follow-up, 4.1 years). Those taking DAPT were followed up for 1 year, as many patients do not continue on DAPT beyond then.
Major adverse cardiac events were reported by 2,183 patients (23.9%) at follow-up. In addition, 7.1% of the cohort had MI, 6.4% were hospitalized for congestive HF, 4.3% had ischemic stroke and 13.4% died, 43% from CV-related causes, during the study period.
Reduced risk
Patients who took ACE inhibitors/angiotensin receptor blockers had a 18% lower risk for major adverse cardiac events (HR = 0.82; 95% CI, 0.73-0.93) than those not taking them. The risk reduction was also seen in patients taking statins (23%; HR = 0.77; 95% CI, 0.68-0.87) compared with those not taking them. A 14% risk reduction for major adverse cardiac events was seen in patients who took beta-blockers (HR = 0.86; 95% CI, 0.74-1.01) vs. those not prescribed them. Patients who took DAPT experienced a nonsignificant risk reduction of 10% (HR = 0.9; 95% CI, 0.74-1.08) 1 year after discharge compared with those not on DAPT.
“Confirmation on the above findings would mandate the evaluation of patients with [MI with nonobstructive coronary arteries] and the initiation of secondary prevention therapies,” Sivabaskari Pasupathy, BSc(Hons), PhD, from The Queen Elizabeth Hospital at the University of Adelaide in Australia, and colleagues wrote in a related editorial. “This would not only be paradigm shifting in relation to the treatment of [MI with nonobstructive coronary arteries], but also provoke a reevaluation of the mechanisms for these beneficial agents in the context of minimal or no atherosclerotic disease.” – by Darlene Dobkowski
Disclosure: Lindahl and Pasupathy report no relevant financial disclosures. Another researcher reports receiving lecture and consultant/advisory board fees from Amgen, Aspen, AstraZeneca and Merck, Sharpe and Dohme.
Perspective
Back to TopC. Noel Bairey Merz, MD, FACC, FAHA
What the findings add to the knowledge base is that we may be missing treatment opportunities. As this study is observational, it would be insufficient to advise treatment guidelines for clinical practice.
We need randomized trials in this area. The WISE investigators are starting a randomized trial in women with [ischemic heart disease], but no [obstructive] CAD, named ischemia-intensive medical therapy (IMT). The intervention is a high-intensity statin and maximally tolerated ACE inhibitors/angiotensin II receptor blockers vs. primary prevention risk-factor management. The trial is expected to start in October.
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