Beta-blockers, one of the most frequently prescribed drugs for heart disease, may not be as effective for certain patients as experts had thought, researchers from the NYU School of Medicine, New York, reported in JAMA (Journal of the American Medical Association).
Beta-blockers are known to help people with badly damaged hearts caused by heart attacks, as well as patients with heart failure. However, beta-blockers are commonly prescribed to stable patients with certain risk factors, but whose hearts are not so fragile, including:
- People with a high risk of developing heart disease
- Patients with CAD (coronary heart disease); their arteries are blocked but they have not had a heart attack
- People who survived a heart attack, even if the damage to the heart was not considerable
Team leader, Sripal Bangalore, M.D., M.H.A. and colleagues found that beta-blockers provide no benefit for these three subgroups of patients.
The authors wrote that when patients with either CAD (coronary artery disease) risk factors only, previous heart attack, or a coronary artery disease without heart attack were prescribed beta-blockers, they did not have a lower risk of cardiovascular death, non-fatal stroke or non-fatal heart attack.
The researchers wrote:
“Treatment with beta-blockers remains the standard of care for patients with coronary artery disease, especially when they have had a myocardial infarction [MI; heart attack]. The evidence is derived from relatively old post-MI studies, most of which antedate modern reperfusion or medical therapy, and from heart failure trials, but has been widely extrapolated to patients with CAD and even to patients at high risk for but without established CAD.
It is not known if these extrapolations are justified. Moreover, the long-term efficacy of these agents in patients treated with contemporary medical therapies is not known, even in patients with prior MI.”
Dr. Bangalore and team set out to determine whether there is a link between beta-blocker usage and long-term cardiovascular outcomes.
They carried out an observational study and gathered data from the Reduction of Atherothrombosis for Continued Health (REACH) registry. 44,708 patients from the registry met the criteria the researchers were seeking for the study. 31% (14,043 patients) of them had prior heart attack, 27% (12,012) had coronary artery disease without no heart attack, and 42% (18,653) had coronary artery disease risk factors only.
They wanted to see what effect beta-blocker therapy might have on cardiovascular death, non-fatal heart attack or non fatal stroke – the study’s primary outcome. The secondary outcome was primary outcome + hospitalization for atherothrombotic events or a revascularization procedure. The patients were followed up midpoint at 44 months. 21,860 of the 44,708 patients were included in the propensity score-matched analysis.
“We have shown in our study that if you have a heart attack and take beta-blockers for a year, you probably will benefit. But the question is, how long after a heart attack would beta-blockers offer a benefit? The European Union says use these drugs long-term only in patients with heart failure. American guidelines say to keep taking them for at least three years after a heart attack.”
Below are some of the results of the study:
- In the Prior Heart Attack Group there was no significant difference between those on beta-blockers and those without beta-blockers:
– 16.93% for those on beta-blockers versus 18.6% for those without beta blockers for the primary outcome
– 30.96% for those on beta-blockers versus 33.12% respectively for the secondary outcome
- In the Coronary Artery Disease without Heart Attack Group there was no significant difference either between those on beta-blockers and those without beta-blockers. In fact, for the secondary outcome the beta-blocker patients fared slightly worse:
– 12.94% versus 13.55% respectively for the primary outcome
– 30.59% versus 27.84% respectively for the secondary outcome and hospitalization (the beta-blocker patients fared worse)
- In the Risk Factors Alone Group those on beta blockers fared worse for the primary outcome
– 14.22% versus 12.11% respectively for the primary outcome
– 20.01% versus 20.17% respectively for the secondary outcome
Among those who had had a heart attack within the previous twelve months, those on beta-blockers were linked to a lower incidence of the secondary outcome.
The authors concluded:
“Among patients enrolled in the international REACH registry, beta-blocker use was not associated with a lower event rate of cardiovascular events at 44-month follow-up, even among patients with prior history of MI. Further research is warranted to identify subgroups that benefit from beta-blocker therapy and the optimal duration of beta-blocker therapy.”
Beta-blockers are a type of medication that block the action of the sympathetic nervous system of the heart; they slow down the heart, reduce the force of the heart muscle’s contractions, and reduce blood vessel contraction in the brain, heart, and the rest of the body.
Beta-blockers “block” beta-adrenergic substances, such as adrenaline (apinephrine) in the involuntary nervous system.
Beta-blockers are most commonly used for the treatment of:
- Heat attack
- Heart failure
- Atrial fibrillation
- Hypertension (high blood pressure) – in 2006, the National Institute for Clinical Excellence (NICE), the UK National Health Service watchdog, said that beta-blockers should not be used routinely for the treatment of hypertension
They are less commonly used for:
Tens of millions of Americans take beta-blockers every day. They are the fifth most widely used prescription medications in the USA. According to IMS Health, 128 million prescriptions were filled in America in 2009.
Written by Christian Nordqvist