Silent brain infarction (SBI) is defined as asymptomatic infarction areas detected in computerized tomography (CT) scans in patients without a history of stroke. The incidence of SBI is increased in CT or magnetic resonance imaging in patients with carotid stenosis and with atrial fibrillation (AF), but its relation with rheumatic mitral stenosis (MS), another major source of emboli, is uncertain. The aim of this study was to investigate the incidence of SBI in patients with MS.
Fifty-three patients with MS (44 females and 9 males; range 25-52 years; mean age 38±7 years) diagnosed by transthoracic echocardiography (TTE) were enrolled in the study. Mitral valve calcification, left atrium (LA) dimension, and the presence of associating mitral regurgitation on TTE were recorded. Electrocardiographic evaluation was done for rhythm analysis and neurologic examination was performed prior to cerebral CT. Carotid artery Doppler examination was carried out in patients with SBI to exclude carotid artery lesions. Patients with a history of hypertension, diabetes mellitus, anticoagulant drug usage, presence of thrombus in LA, left ventricular segmental or systolic dysfunction, or other valve diseases were excluded from the study.
The incidence of SBI was found to be 24.5% in patients with MS (47% cortical, 53% lacunar). SBI was observed to be significantly high in patients with LA dimension >4 cm or in patients with AF (p<0.05). The SBI incidence was markedly higher if AF was found with enlarged LA when compared with patients having sinus rhythm and small LA (p<0.01). When moderate to severe mitral regurgitation was associated with MS, the SBI incidence was found to be lower (p<0.05). Although SBI was higher in patients with MVA<1.5 cm², it was not statistically significant (p>0.05). No significant correlation was found between calcific and noncalcific valves for SBI (p>0.05).
Our data suggest that SBI may be expected in about 1/4 of patients with MS. The presence of LA enlargement and AF increase the incidence of SBI in patients with MS, whereas the presence of moderate to severe mitral regurgitation decreases the incidence of SBI.