A Samsung Medical Center research team has found that maintaining beta-blocker therapy in acute myocardial infarction (AMI) patients without heart failure for more than a year has lowered long-term mortality than cutting the treatment.

Beta-blocker reduces the ischemic burden of the heart and has antiarrhythmic effects. However, determining an appropriate treatment period is significant as the drug can cause side effects such as slow heart rate, low blood pressure, and claudication. International guidelines recommend starting beta-blocker treatment early in all AMI unless there are special occasions where the treatment can worsen the patient.

A research team of Samsung Medical Center has found that keeping the beta-blocker therapy for more than a year lowered mortality rate in patients with acute myocardial infarction. From left, Professors Han Joo-yong, Kim Ji-hoon, Cho Ju-hee, and Kang Dan-bi. (SMC)

The researchers followed up and analyzed 28,970 patients over 18 years of age without heart failure among people with myocardial infarction in the National Health Insurance Service's national cohort, the hospital said.

They used landmark analysis to prevent immortal time bias, often committed in the epidemiological studies of medicine, and assessed beta-blocker therapy's efficacy for one, two, and more than three years.

Among the total, 1,694 patients died during the follow-up, and 25.7 deaths per 1,000 person-years were reported when the beta-blocker treatment was maintained for less than a year. When the beta-blocker was kept for more than a year, only 13.1 deaths per 1,000 person-years occurred.

In the case of hospitalized patients because of the recurrence of AMI and heart failure, those who received beta-blockers for more than a year showed an 18 percent lower risk.

These results showed a similar tendency when using beta-blockers for two and longer than three years, suggesting that the use of beta-blockers lowered the risk of long-term mortality and related disease.

“Although the introduction of reperfusion therapy in AMI significantly improved the outcome of treatment, the disease still has a high mortality rate, and some of the surviving patients suffered greatly from heart failure,” said Professor Hahn Joo-yong who led the study.

Further studies are necessary to standardize the treatment to improve long-term prognosis after experiencing AMI, he added.

European Heart Journal has published the findings in the latest issue.

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