Mitral annular calcification is an independent predictor of adverse cardiovascular events, particularly MI and vascular death, investigators report.

Mitral annular calcification (MAC) - ie, calcification of the mitral valve support ring - is an independent predictor of adverse cardiovascular events, particularly MI and vascular death, investigators with the Northern Manhattan Study report.

Dr. Marco R. Di Tullio of Columbia University in New York and colleagues followed a cohort of 1,955 subjects, aged 40 years and older, 56.8 per cent Hispanic, with no prior history of MI or ischemic stroke, for a mean of 7.4 years.

At baseline, the team found that 519 subjects (26.6 per cent) had MAC. During follow-up, MI occurred in 100 patients (5.1 per cent), ischemic stroke occurred in 104 patients (5.3 per cent) and vascular death occurred in 155 patients (8.0 per cent).

MAC conferred an adjusted hazard ratio (HR) of 1.75 for MI and 1.53 for vascular death. The risk of ischemic stroke was not significantly increased with MAC, the investigators report in the September issue of the Journal of the American College of Cardiology: Cardiovascular Imaging.

Information on MAC thickness was available in 498 patients. It showed that 253 patients (13.1 per cent) had mild to moderate MAC, defined as 1 mm to 4 mm, and 245 patients (12.7 per cent) had severe MAC greater than 4 mm in thickness.

The thickness of MAC correlated with the level of risk, with MAC greater than 4 mm "a strong and independent predictor" of MI and vascular death. The adjusted HR was 1.89 for MI and 1.81 for vascular death. There was a "borderline association" between greater MAC thickness and ischemic stroke, with an adjusted HR of 1.59.

"The clinical significance of our findings lays in the fact that the presence and severity of mitral annular calcification predicts the risk of future cardiovascular events, and can therefore be seen as a 'warning sign' of increased risk in individual subjects," Dr. Di Tullio told Reuters Health.

"No treatment is known to affect MAC directly, but even if such treatment existed, it is not certain that the associated incidence of events would necessarily be affected," he explained.

"The way I see it, MAC is probably a marker of future cardiovascular risk rather than a direct cause for cardiovascular events, like an integrated indicator of the actions of different vascular risk factor (hypertension, hypercholesterolemia, etc.) over time. Therefore, finding MAC in an individual should be a reminder of the need of a more aggressive treatment of other known cardiovascular risk factors," Dr. Di Tullio concluded.

J Am Coll Cardiol Img 2008;1:617-623