Mitral Annular Calcium and Stroke
August 1, 1998 2 minutes read
Mitral Annular Calcium and Stroke
ABSTRACT & COMMENTARY
Synopsis: Mitral annular calcium increases the incidence of atrial fibrillation and stroke in patients older than 60 years.
Source: Aronow WS, et al. Am J Cardiol 1998;81: 105-106.
Although a higher incidence of stroke has been observed in patients with mitral annular calcium (MAC), its relationship to atrial fibrillation and mitral valve hemodynamic abnormalities has not been clarified in relation to stroke. Thus, Aronow and associates prospectively studied 2148 patients older than 60 years. About half the patients had MAC; 14% had atrial fibrillation, and it was more common in those with MAC (22% vs 8%; P < 0.001). New thrombotic stroke occurred in 453 of the patients. Multivariate analysis identified several independent predictors of stroke: atrial fibrillation (risk ratio [RR], 3.0); MAC (RR, 2.6); prior stroke; and male sex (RR, 1.6). The presence of mitral stenosis or regurgitation due to MAC increased the incidence of stroke, but they were not independent predictors. Aronow et al conclude that MAC increases the incidence of atrial fibrillation and stroke in patients older than 60 years.
COMMENT BY MICHAEL H. CRAWFORD, MD
The patients with the highest incidence of stroke were those with atrial fibrillation and mitral stenosis due to MAC at 74%, but this group only accounted for 31 of the 453 strokes. The group with sinus rhythm and MAC without mitral hemodynamic abnormalities accounted for the highest absolute number of strokes (148), because there were a lot of patients in this group. This confirms the risk of MAC alone for subsequent stroke. These data suggest that even in older patients with sinus rhythm and normal mitral valve function, long-term anticoagulation should be considered if MAC is discovered.
Aronow et al do not explain why these patients got echocardiograms, and, certainly, we cannot recommend routine echoes for everyone older than 60 years of age. However, if a patient gets an echo and MAC is found, chronic anticoagulation should be considered. It cannot be definitively recommended until prospective, controlled treatment trials are done to establish efficacy. Also, perhaps aspirin would be beneficial. This would also need to be tested, but, at this time, aspirin could be an alternative therapy in those with contraindications to warfarin.
MAC is also encountered frequently in younger patients with chronic renal failure and Marfan's syndrome. Whether in such patients MAC increases stroke risk is not known, so anticoagulants probably should be withheld unless other indications for them exist.
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