Contrast-enhanced magnetic resonance imaging identifies focal regions of intramyocardial fibrosis in patients with severe aortic valve disease: Correlation with quantitative histopathology
Received 11 March 2008; accepted 18 September 2008. published online 10 December 2008.
Background
Chronic aortic valve disease (AVD) is characterized by progressive accumulation of interstitial myocardial fibrosis (MF). However, assessment of MF accumulation has only been possible through histologic analyses of endomyocardial biopsies. We sought to evaluate contrast-enhanced magnetic resonance imaging (ce-MRI) as a noninvasive method to identify the presence of increased MF in patients with severe AVD.
Methods
Seventy patients scheduled to undergo aortic valve replacement surgery were examined by cine and ce-MRI in a 1.5-T scanner. Cine images were used for the assessment of left ventricular (LV) volumes, mass, and function. Delayed-enhancement images were used to characterize the regions of MF. In addition, histologic analyses of myocardial samples obtained during aortic valve replacement surgery were used for direct quantification of interstitial MF. Ten additional subjects who died of noncardiac causes served as controls for the quantitative histologic analyses.
Results
Interstitial MF determined by histopathologic analysis was higher in patients with AVD than in controls (2.7% ± 2.0% vs 0.6% ± 0.2%, P = .001). When compared with histopathologic results, ce-MRI demonstrated a sensitivity of 74%, a specificity of 81%, and an accuracy of 76% to identify AVD patients with increased interstitial MF. There was a significant inverse correlation between interstitial MF and LV ejection fraction (r = −0.67, P < .0001). Accordingly, patients with identifiable focal regions of MF by ce-MRI exhibited worse LV systolic function than those without MF (45% ± 14% vs 65% ± 14%, P < .0001).
Conclusions
Contrast-enhanced MRI allows for the noninvasive detection of focal regions of MF in patients with severe AVD. Moreover, patients with identifiable MF by ce-MRI exhibited worse LV functional parameters.
Heart Institute (InCor) University of São Paulo Medical School, São Paulo, Brazil
Reprint requests: Carlos E. Rochitte, Director of Cardiovascular MRI and CT, Instituto do Coração (InCor)–Setor de Ressonância Magnética Cardiovascular, Av. Dr Enéas de Carvalho Aguiar, 44, Andar AB, Cerqueira César, São Paulo, SP, Brazil, 05403-000.
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