Mitral annulus calcification is not an independent risk factor for stroke: a cohort study of 657 patients
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All studies but one in the past have shown a strong relative risk of mitral annulus calcification for stroke, but the contribution of associated cardiac and vascular risk factors, especially carotid atheroma has not been appreciated. We studied the risk of stroke in selected patients with mitral annular calcification, adjusting for clinical, echocardiographic and therapeutic factors influencing stroke risk. Of 8,160 consecutive patients with echocardiograms, 657 with and 562 without mitral annulus calcification were followed for a mean of 2.4 years (range 1–6.6) to determine stroke risk by means of proportional hazards models with clinical, echocardiographic, and therapeutic variables that influence the risk of stroke. We also determined the association of mitral annulus calcification with subtypes of ischaemic brain lesions generally considered to be specific for an underlying cardio-embolic cause. We therefore distinguished between territorial, small deep, and asymptomatic (silent) brain infarcts. Fifty-one patients with mitral annulus calcification and 27 controls had a stroke in the follow-up period. Mitral annulus calcification was not significantly associated with stroke in proportional hazards models (hazard ratio 0.76, 95% confidence interval 0.42–1.36, P = 0.3), or with any of the stroke subtypes, or with the presence of silent brain infarcts after adjustments for risk factors for generalized vascular disease Hypertension and carotid atheroma, with or without stenosis, ipsilateral or contralateral to the side of the stroke, were significantly associated with stroke in our patients. This study does not support the view that mitral annulus calcification is a risk factor for stroke. As others have found strong associations between mitral annulus calcification and cardiac and vascular risk factors for stroke, the increased risk of stroke in patients with mitral annulus calcification reported may be explained by these confounding risk factors. Therefore, in our opinion, mitral annulus calcification requires treatment of cardiovascular risk factors, but generally no specific measures such as surgery or oral anticoagulants are required to lower the risk of stroke.
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