Anti-inflammatory drugs could cut the risk of heart attacks and strokes, a study of 10,000 patients suggests.
A trial of the drug canakinumab could represent the biggest breakthrough in treatment since the advent of statins to lower cholesterol, its authors say.
The study reported a 15% reduction in the risk of a repeat heart attack among patients - but others questioned the drug's efficacy, side-effects and cost.
Recipients of the drug had an increased risk of potentially fatal infections.
However, the British Heart Foundation (BHF) said the "exciting and long-awaited trial" could still help save lives.
Arthritis drug
Heart attack patients are routinely given cholesterol-lowering statins and blood-thinning drugs to help reduce the risk of repeat attacks.
In this study, 10,000 patients who had previously had a heart attack were treated with the anti-inflammatory drug once every three months.
The trial, held in almost 40 countries, monitored the individuals for up to four years.
It found what researchers said were reductions in risk "above and beyond" those seen in patients who only took statins.
However, it also found a "significantly higher incidence" of potentially fatal infection and sepsis among those treated with the drug, according to the study.
The results were presented at the European Society of Cardiology meeting, held in Barcelona, Spain.
Canakinumab was initially developed by pharmaceutical firm Novartis - which paid for the trial - to treat rheumatoid arthritis.