Prognostic Significance of Myocardial Fibrosis Quantification by Histopathology and Magnetic Resonance Imaging in Patients With Severe Aortic Valve Disease
OBJECTIVES: Does myocardial fibrosis (MF) in patients with severe aortic valve (AV) disease, assessed by histopathology or contrast-enhanced magnetic resonance imaging (ce-MRI), predict outcomes following surgical AV replacement?
METHODS: Fifty-four patients (mean age 46.8 years, 78% male) with symptomatic severe aortic regurgitation (n = 26) or aortic stenosis (n = 28) were prospectively evaluated. All patients underwent preoperative quantitative assessment of MF by ce-MRI and had myocardial tissue samples obtained during surgery for histopathologic evaluation. Patients were grouped based on degree of MF and were compared to assess for differences in left ventricular (LV) functional improvement and survival postoperatively.
RESULTS: ce-MRI assessment of MF correlated well with histopathology (r = 0.69, p < 0.0001), and the degree of MF was higher in the study group than in normal controls. LV functional changes were evaluated in 25 patients who underwent follow-up MRI; LV mass was decreased and LV ejection fraction (EF) improved (EF 54 ± 10% pre-op vs. 59 ± 14% post-op, p = 0.02). LVEF improvement was inversely related to the degree of pre-op MF. Overall, those who died had more MF, and this increased burden of MF was associated with lower postoperative survival. Finally, on multivariate analysis, the amount of MF, along with advanced age, independently predicted all-cause mortality.
CONCLUSIONS: In patients with severe AV disease, the amount of MF assessed by histopathology or ce-MRI is associated with LV function improvement and mortality.
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