Mitral annular calcification and the risk of stroke in an elderly cohort.
BACKGROUND
Previous clinical studies have suggested that there is an association between mitral annular calcification and the risk of stroke, but it is unclear whether this association is independent of the traditional risk factors for stroke. We examined the relation between mitral annular calcification and the incidence of stroke in a population-based study.


METHODS
Subjects in the Framingham Study receiving a routine examination underwent M-mode echocardiography to determine the presence and severity (thickness in millimeters) of mitral annular calcification. The incidence of stroke during eight years of follow-up was analyzed with a proportional-hazards model adjusting for the calcification, age, sex, systolic blood pressure, diabetes mellitus, cigarette smoking, atrial fibrillation, and coronary heart disease or congestive heart failure.


RESULTS
Among 1159 subjects whose echocardiograms could be assessed for mitral annular calcification and who had no history or current evidence of stroke at the index examination (51 percent of all subjects), the prevalence of mitral annular calcification was 10.3 percent in the men and 15.8 percent in the women. Multivariate analysis demonstrated that the presence of mitral annular calcification was associated with a relative risk of stroke of 2.10 (95 percent confidence interval, 1.24 to 3.57; P = 0.006). There was a continuous relation between the incidence of stroke and the severity of mitral annular calcification; each millimeter of thickening as shown on the echocardiogram represented a relative risk of stroke of 1.24 (95 percent confidence interval, 1.12 to 1.37; P less than 0.001). Furthermore, even when subjects with coronary heart disease or congestive heart failure were excluded from the analysis, subjects with mitral annular calcification still had twice the risk of stroke.


CONCLUSIONS
In an elderly, longitudinally followed population-based cohort, mitral annular calcification was associated with a doubled risk of stroke, independently of traditional risk factors for stroke. Whether such calcification contributes causally to the risk of stroke or is merely a marker of increased risk because of its association with other precursors of stroke remains unknown.
Benjamin
E J
EJ
Framingham Heart Study, Mass.
Plehn
J F
JF
D'Agostino
R B
RB
Belanger
A J
AJ
Comai
K
K
Fuller
D L
DL
Wolf
P A
PA
Levy
D
D
D000328:Adult; D000368:Aged; D002114:Calcinosis / Q000150:complications* / Q000000981:diagnostic imaging; D002561:Cerebrovascular Disorders / Q000209:etiology*; D015331:Cohort Studies; D003327:Coronary Disease / Q000150:complications; D004452:Echocardiography; D005260:Female; D005500:Follow-Up Studies; D006349:Heart Valve Diseases / Q000150:complications* / Q000000981:diagnostic imaging; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000473:pathology*; D015999:Multivariate Analysis; D016016:Proportional Hazards Models; D012306:Risk