Prognostic value of myocardial fibrosis in patients with severe aortic valve stenosis

Objective: To evaluate whether myocardial fibrosis influences left ventricular performance in severe aortic stenosis and to assess its effect on long-term survival after aortic valve replacement. Methods: Myocardial fibrosis was evaluated in biopsy specimens taken from the interventricular septum in 99 patients undergoing aortic valve replacement because of severe or prevalent aortic stenosis. Clinical and echocardiographic evaluations were performed at a mean follow-up of 6.2 +/- 3.0 years. The patients were classified according to the myocardial fibrosis severity (none or mild in 28, moderate in 52, and severe in 19). Results: Patients with severe myocardial fibrosis had a dilated left ventricle and positive association between the left ventricular end-diastolic diameter (R = 0.77, P < .001), left ventricular end-systolic diameter (R = 0.78, P < .001), left ventricular end-systolic wall stress (R = 0.74, P < .001) and the degree of myocardial fibrosis. Myocardial fibrosis was inversely related to left ventricular fractional shortening (R = -0.64, P < .001), left ventricular ejection fraction (R = -0.53, P < .001), and left ventricular relative wall thickness (R = -0.70, P < .001). Patients with a higher grade of myocardial fibrosis had a significantly lower freedom from cardiac death at 10 years (42% +/- 19% vs 89% +/- 6%, P = .002), with congestive heart failure the most common cause of death. At Cox regression analysis, patient age (P = .012), low preoperative transvalvular gradient less than 40 mm Hg (P = .040), preoperative end-systolic wall stress (P = .046), and preoperative myocardial fibrosis grade (P = .034) emerged as the strongest independent predictors of mortality. Conclusions: In patients with severe aortic valve stenosis, the amount of myocardial fibrosis appears to have significant effect on clinical status and long-term survival after aortic valve replacement. From these results, we believe that new strategies for the earlier detection of myocardial fibrosis are needed to achieve a better prognostic outcome. (J Thorac Cardiovasc Surg 2012; 144: 830-7)