Beta blockers, a class of drugs, used to lower blood pressure, improve pumping of the heart, and prevent another heart attack, are often considered safe to use. But recent studies have negated the theory and claimed that they are not effective after a year of a heart attack.
A cohort study, ‘Association of beta-blockers beyond 1 year after myocardial infarction (heart attack) and cardiovascular outcomes,’ published in the journal Heart claims that beta blockers therapy for survivors of heart attack is not associated with improved heart function after a year. However, experts who spoke to Happiest Health say this study is inconclusive and needs more evidence to support the claim.
What are beta blockers?
Experts say beta blockers are a class of antihypertensive medications. It is usually prescribed to people with coronary artery disease, history of heart attack, arrhythmias like atrial fibrillation, ventricular tachycardia, ventricular fibrillation and valvular diseases like hypertrophic cardiomyopathy. Dr Abhijit Vilas Kulkarni, senior interventional cardiologist, Apollo Hospitals, Bengaluru, says the evidence for beta blockers in heart failure is very strong and cannot be refuted. He says, “The role and efficacy of beta blockers used to treat hypertension is sometimes questioned. Earlier, there were no newer drugs to treat hypertension. So, it was accepted well. Now, newer drugs have come up with more evidence in treating long-term hypertension. It is basically a competition between the two.”
Dr Sreekanth B. Shetty, Senior Consultant and Head – Interventional Cardiology, Sakra World Hospital, Bengaluru says, “Over time, beta blockers have shown to reduce the risk of sudden cardiac arrest in people with history of heart attack and weak hearts (when pumping of the heart is less than 40 per cent).”
Experts opine that the study reflects what they already know. Dr Pravin Kahale, Consultant Cardiology, Kokilaben Dhirubhai Ambani Hospital, Mumbai, says, “It is a well-known fact that beta blockers are not useful when the pumping of the heart is good. Earlier studies said that they are not very beneficial after three years of a heart attack and this study says one year. That’s the difference,” he says, adding that the biggest problem about beta blockers is their underuse due to fear created by these studies.
Beta blockers for heart failure
Dr Shetty says it is also important to understand the people who benefit the most from beta blockers. They include people with chronic heart failure, heart muscle dysfunction, history of arrhythmias and those with untreated blockages. “Now, what has happened over time is that most people with a history of heart attack have had early treatment with reperfusion therapy (which includes thrombolytic drugs or angioplasty). And because of early treatment of the heart attack, and complete revascularization, people are less likely to develop residual ischemia (untreated blockages). So, in a broad group of people with a history of heart attack, beta blockers may not be so useful as a lot of them have reasonable heart function,” he says.
Dr Kahale adds that, often, a person with a heart condition, while undergoing a non-cardiac surgery, is not given beta blockers. “Earlier studies have stated that they are harmful when given during such procedures. But these studies have used high doses of beta blockers, which will affect the person. No person with heart condition will be able to tolerate such high doses. The dose should be increased gradually,” he adds.
Side effects of beta blockers
Experts say the study does not reflect the utility of beta blockers in specific situations in people post heart attack. Dr Kulkarni adds they reduce the heart rate. “People after a heart attack are at risk for arrhythmias or increased heart rates. Beta blockers are required to prevent that,” he says.
Dr Shetty also says they are relatively safe drugs. “As they are anti-hypertension medication, they can cause low BP. They also reduce heart rate and may hence, cause tiredness,” he says. He adds that the newer version of beta blockers have minimal side effects like depression. And they are withdrawn when the person demonstrates a reasonably healthy heart.
Dr Kulkarni adds every drug has side effects. “But the side effects caused are much lesser compared to their positive effect,” he says.
People with heart muscle dysfunction are given beta blockers for their entire lifetime. Dr Kahale, in fact, says people with low heart pumping capacity should speak to their cardiologists about beta blockers.
Takeaways
- Beta blockers are usually prescribed to people with coronary artery disease, a history of heart attack, arrhythmias and valvular diseases.
- A recent study claims that the class of drugs used for lowering blood pressure may not be effective for a person without heart failure, after a year of a heart attack.
- These drugs may also have side effects like low BP, depression and fatigue. However, experts say they are minimal and temporary.
- Experts say it is important to understand who would benefit the most from beta blockers and prescribe them accordingly.
