Antibiotics are not effective in preventing heart attacks, despite growing evidence that inflammation plays a key role in cardiovascular disease, researchers said on Monday.

Bacteria have been found in the artery-clogging plaques of many cardiovascular disease patients, prompting several clinical trials. But scientists have failed to show that fighting these infections with antibiotics can prevent heart attacks.

Christopher Cannon, of Brigham and Women’s Hospital, Boston, said negative results from two new major studies - each involving more than 4,000 patients - had effectively closed the door on the idea.

Details of the two studies, which involved Bristol-Myers Squibb’s drug Tequin, or gatifloxacin, and Pfizer’s Zithromax, or azithromycin, were presented at the annual meeting of the European Society of Cardiology.

Cannon said it was still possible that common bacteria like Chlamydia pneumoniae contributed to plaque build-up but it was probably a life-long process and by the time people were at serious risk of heart attacks it was too late to make a difference.

“This restimulates us to refocus on things that we know that do work - of which there are many - including anti-platelet therapy, beta blockers, ACE inhibitors and statins,” he told reporters.

Researchers said the results of other trials supported the early and aggressive use of cholesterol-lowering statins, in particular, in patients suffering acute coronary syndromes.

One new 2-year trial that included 4,497 patients arriving at hospital with chest pain found that those who were immediately put on Merck and Co’s statin Zocor appeared to do better than those who did not receive treatment for 4 months.

Michael Blazing, also of Brigham and Women’s Hospital, said that 14.4 percent of patients on Zocor died or suffered major cardiac problems, compared to 16.7 percent of those treated later. The difference was not statistically significant but he said the results added to evidence about the benefits of early statin therapy.