The drug treatment that is primarily used for the management of irregular heart rhythms, angina, and high blood pressure to prevent heart failure or a life-threatening complication of heart attacks, was found to have no discernible impact on the risk of these conditions.
According to a significant study published in the journal Heart, the accepted clinical practice of prescribing beta blockers over an extended period to mitigate the risk of subsequent heart attacks or death may not be justified for patients without heart failure.
The researchers discovered no discernible disparity in these risks between individuals who were prescribed beta blockers more than a year after experiencing a heart attack and those who did not receive these medications.
Beta-blockers belong to a class of drugs primarily employed in the management of abnormal heart rhythms, angina, and high blood pressure. Following a heart attack, they are commonly prescribed as part of secondary prevention to reduce the chances of recurrence and other cardiovascular complications.
However, the efficacy of these drugs in patients without heart failure or left ventricular systolic dysfunction (LVSD), a potentially fatal complication following a heart attack, remains uncertain beyond the initial year.
The researchers highlight that most existing evidence is derived from clinical trials conducted prior to significant changes in the routine care of heart attack patients.
Study Challenges Long-Term Beta Blocker Use for Heart Attack Patients without Heart Failure
The researchers leveraged data from the National Swedish register for coronary heart disease (SWEDEHEART) to examine the outcomes of 43,618 adults who had experienced a heart attack between 2005 and 2016 and required hospital treatment, but did not have heart failure or LVSD.
Of these patients, 34,253 were prescribed beta blockers and remained on the medication one year after hospital discharge, while 9,365 were not.
The study aimed to determine if there were any differences in deaths from any cause, rates of further heart attacks, revascularization procedures, or hospital admissions for heart failure between the two groups.
The real-time data collected over an average monitoring period of 4.5 years revealed that long-term use of beta blockers was not associated with improved cardiovascular outcomes.
In fact, 19% of those on beta blockers (6,475) and 22% of those who were not (2,028) died from any cause, experienced another heart attack, required unscheduled revascularization, or were hospitalized for heart failure.
Even after controlling for influential factors such as demographics and relevant co-existing conditions, there was no discernible difference in the incidence of these events between the two groups.
Study Findings Should Be Interpreted with Caution
In what is the largest observational study of its kind to date, researchers emphasize that while the study sheds important light on the topic, it cannot establish a cause-and-effect relationship. The findings should be considered in the context of certain limitations, as acknowledged by the researchers.
Notably, patients were not randomly assigned to treatment, and only specific cardiovascular outcomes were examined, omitting other potential factors. Additionally, the study lacked information regarding patients’ adherence to drug regimens and their overall quality of life.
Furthermore, there were notable differences between the two groups in terms of factors known to influence the risk of adverse cardiovascular outcomes.
Nonetheless, the researchers highlight that beta blockers, despite being associated with side effects such as depression and fatigue, should prompt a reevaluation of the long-term value of these drugs for heart attack patients without heart failure or left ventricular systolic dysfunction (LVSD).
In an editorial linked to the study, Professor Ralph Stewart and Dr. Tom Evans from Green Lane Cardiovascular Services in Auckland, New Zealand (Aotearoa), highlight the ongoing uncertainty regarding the benefits of long-term beta-blocker use in lower-risk patients who are already receiving evidence-based therapies and have normal heart function.
“Despite strong evidence that long-term beta-blockers can improve outcomes after [heart attack], it has been uncertain whether this benefit applies to lower risk patients who are taking other evidence-based therapies and who have a [normal functioning heart].
“Recommendations on the duration of beta blocker therapy are variable or absent because this question was not specifically evaluated in clinical trials. Most patients take daily medications for many years after a [heart attack] because they believe they are beneficial.
“[This] study raises an important question directly relevant to the quality of care—do patients with a normal [functioning heart] benefit from long term beta-blocker therapy after [heart attack]? To answer this question, more evidence from large randomised clinical trials is needed.”
Source: 10.1136/heartjnl-2022-322115
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