Statins are the mainstay drugs for heart attack prevention and work primarily by lowering cholesterol levels. But a quarter of people who have one heart attack will suffer another within five years despite taking statins regularly. It is believed this is because of unchecked inflammation within the heart’s arteries.
The research team, led from Brigham and Women’s hospital in Boston, tested whether targeting the inflammation with a potent anti-inflammatory agent would provide an extra benefit over statin treatment.
The researchers enrolled more than 10,000 patients who had had a heart attack and had a positive blood test for inflammation into the trial, known as the Cantos study. All patients received high doses of statins as well as either canakinumab or a placebo, both administered by injection every three months. The trial lasted for four years.
For patients who received the canakinumab injections the team reported a 15% reduction in the risk of a cardiovascular event, including fatal and non-fatal heart attacks and strokes. Also, the need for expensive interventional procedures, such as bypass surgery and inserting stents, was cut by more than 30%. There was no overall difference in death rates between patients on canakinumab and those given placebo injections, and the drug did not change cholesterol levels.
Dr Paul Ridker, who led the research team, said the study “ushers in a new era of therapeutics”.
“For the first time, we’ve been able to definitively show that lowering inflammation independent of cholesterol reduces cardiovascular risk,” he said.
“This has far-reaching implications. It tells us that by leveraging an entirely new way to treat patients – targeting inflammation – we may be able to significantly improve outcomes for certain very high-risk populations.”
The hospital said the reductions in risk were “above and beyond” those seen in patients who only took statins.
Ridker said the study showed that the use of anti-inflammatories was the next big breakthrough following the linkage of lifestyle issues and then statins.
“In my lifetime, I’ve gotten to see three broad eras of preventative cardiology,” he said. “In the first, we recognised the importance of diet, exercise and smoking cessation. In the second, we saw the tremendous value of lipid-lowering drugs such as statins. Now, we’re cracking the door open on the third era. This is very exciting.”
But there were some downsides to the treatment. The researchers reported an increase in the chances of dying from a severe infection of about one for every 1,000 people treated, although this was offset by an unexpected halving of cancer deaths across all cancer types. In particular, the odds of succumbing to lung cancer were cut by over 75%, for reasons the team do not yet understand. The researchers are planning further trials to investigate canakinumab’s potentially protective effect against cancer.
Prof Martin Bennett, a cardiologist from Cambridge who was not involved in the study, said the trial results were an important advance in understanding why heart attacks happen. But, he said, he had concerns about the side effects, the high cost of the drug and the fact that death rates were not better in those given the drug.
“Treatment of UK patients is unlikely to change very much as a result of this trial, but the results do support investigation of other drugs that inhibit inflammation for cardiovascular disease, and the use of this drug in cancer,” he said.
Prof Jeremy Pearson, associate medical director at the British Heart Foundation, was optimistic about the trial opening the door to new types of treatment for heart attacks.
“Nearly 200,000 people are hospitalised due to heart attacks every year in the UK,” Pearson said. “Cholesterol-lowering drugs like statins are given to these people to reduce their risk of another heart attack and this undoubtedly saves lives. But we know that lowering cholesterol alone is not always enough.
“These exciting and long-awaited trial results finally confirm that ongoing inflammation contributes to risk of heart disease, and [lowering it] could help save lives.”
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