New evidence suggests a role for increased homocysteine in the blood.
Several studies have suggested a link to several infectious agents, such as cytomegalovirus, chlamydia, and others, but it is unclear if these agents really cause disease or if they are found in plaques that have already developed due to other causes. Researchers are also interested in factors that cause a plaque to rupture and induce a heart attack. There is good evidence that the rupture is preceded by an inflammatory reaction of some sort. However, physicians should not recommend treating all coronary artery disease patients with antibiotics. Studies show that the common bacterium Chlamydia pneumoniae, which causes respiratory infections, may be partly to blame.