Many heart attack patients prescribed beta-blockers may not benefit

People who have had a heart attack are prescribed a number of drugs, often for life. Our latest research shows that one of those drugs – a beta-blocker – may offer no survival benefit to heart attack patients who do not have heart failure.

This may not seem important, but research shows that the more drugs a person is prescribed, the less likely they are to take them. And this includes the important pills, such as statins and aspirin, which really could save a person’s life. What’s more, drugs have side effects, which, for beta-blockers, may include dizziness, tiredness, blurred vision and nausea.

Beta-blockers were invented in the 1960s, a time when deaths from heart attacks were very common. Scientists knew that stress (through increased adrenaline) could trigger a heart attack. This led to the development of the drug which works by blocking the effects of adrenaline and lowers the heart rate and blood pressure. Nowadays, beta-blockers are often prescribed as part of routine heart attack care.

A heart attack occurs when there is a loss of blood flow to part of the heart, causing the heart muscle to be damaged. Heart failure, on the other hand, occurs when the heart is unable to effectively pump blood through the body due to weakened heart muscles. One of the most common reasons for heart failure is a previous heart attack.

Earlier evidence showed that beta-blockers can increase a person’s lifespan after a heart attack. But this evidence predates other advances in heart attack treatment. These advances include the introduction of operations such as angiograms, stents and bypass grafts. The use of these operations has led to significant improvements in survival following a heart attack.

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Although more modern evidence from clinical trials about the use of beta-blockers exists, the evidence is focused on heart attack patients who also have heart failure. So doctors are unsure about the use of beta-blockers for heart attack patients who do not also have heart failure. This uncertainty is reflected by various national treatment guidelines which differ in their recommendation for the use of beta-blockers.

Due to the availability of national clinical data on heart attacks in the UK, we were able to assess the effectiveness of beta-blockers in heart attack patients who did not have heart failure. Importantly, we were able to assess the effectiveness of beta-blockers in a modern-treatment era at relatively low cost and in a timely manner compared with a clinical trial.

We used two methods to analyse the data – propensity score analyses and instrumental variable analyses – which allowed us to take into consideration the differences between patients who received beta-blockers and those who did not, such as their age, sex, type of heart attack and any other medications and treatments they received. The methods also allowed us to mimic the random treatment allocation of a clinical trial to get results that are more robust than a conventional observational study.

We found that, for nearly 180,000 patients with a heart attack who did not have heart failure, 95 per cent of patients were prescribed beta-blockers when they left hospital. But there was no survival benefit for these patients.

This study now raises questions over whether patients who do not have heart failure should continue to be routinely prescribed beta-blockers following their heart attack.

Although we provide strong evidence that beta-blockers may not improve survival following a heart attack for patients without heart failure, modern clinical trials are still needed to confirm the findings and provide conclusive evidence to change treatment guidelines. This work has the potential to save patients from being overtreated while also saving them money on the cost of prescriptions.

Marlous Hall is a senior epidemiologist at the University of Leeds. This article was originally published on The Conversation (www.conversation.com)