Prognostic Significance of Myocardial Fibrosis Quantification by Histopathology and Magnetic Resonance Imaging in Patients With Severe Aortic Valve Disease

Objectives We sought to determine whether the quantitative assessment of myocardial fibrosis (MF), either by histopathology or by contrast-enhanced magnetic resonance imaging (ce-MRI), could help predict long-term survival after aortic valve replacement. Background Severe aortic valve disease is characterized by progressive accumulation of interstitial MF. Methods Fifty-four patients scheduled to undergo aortic valve replacement were examined by ce-MRI. Delayed-enhanced images were used for the quantitative assessment of MF. In addition, interstitial MF was quantified by histological analysis of myocardial samples obtained during open-heart surgery and stained with picrosirius red. The ce-MRI study was repeated 27 ± 22 months after surgery to assess left ventricular functional improvement, and all patients were followed for 52 ± 17 months to evaluate long-term survival. Results There was a good correlation between the amount of MF measured by histopathology and by ce-MRI (r = 0.69, p < 0.001). In addition, the amount of MF demonstrated a significant inverse correlation with the degree of left ventricular functional improvement after surgery (r = −0.42, p = 0.04 for histopathology; r = −0.47, p = 0.02 for ce-MRI). Kaplan-Meier analyses revealed that higher degrees of MF accumulation were associated with worse long-term survival (chi-square = 6.32, p = 0.01 for histopathology; chi-square = 5.85, p = 0.02 for ce-MRI). On multivariate Cox regression analyses, patient age and the amount of MF were found to be independent predictors of all-cause mortality. Conclusions The amount of MF, either by histopathology or by ce-MRI, is associated with the degree of left ventricular functional improvement and all-cause mortality late after aortic valve replacement in patients with severe aortic valve disease.