Prognostic implications of fibrosis in low risk aortic stenosis patients

INTRODUCTION AND OBJECTIVES:Among patients with aortic stenosis (AS), interstitial fibrosis has been associated with progression to heart failure and is a marker of poorer prognosis. We aimed to assess the impact of myocardial fibrosis on clinical events after aortic valve replacement (AVR) in low risk, severe AS. METHODS:We prospectively followed 56 severe AS patients with ejection fraction >40%, who underwent AVR with simultaneous myocardial biopsies and collagen volume fraction (CVF) determination. Baseline and follow-up echocardiographic parameters were assessed. Outcomes were all-cause death and the combined endpoint of all-cause death or non-fatal cardiovascular hospitalization. RESULTS:Patients were predominantly women (67.9%) and mean age was 66±12 years. At follow-up, there was a significant decrease in transaortic gradients and wall stress, as well as regression in indexed LV mass. Patients who suffered a fatal event or the combined endpoint had a higher degree of fibrosis (27.1±20.7% vs. 15.4±11.8%, p=0.035; 24.0±18.2% vs. 15.3±12.0%, p=0.038, respectively). Patients with CVF≥15.4% had higher rates of all-cause death (37.5% vs. 97.0%, p=0.001) and lower survival free of the combined endpoint of all-cause death or non-fatal cardiovascular hospitalization (0% vs. 91.2%, p<0.001). CVF was the only independent predictor of all-cause death (hazard ratio (HR) 1.88; 95% confidence interval (CI): 1.08-3.29 for each 10% increase; p=0.026) and all-cause death or cardiovascular hospitalization (HR 1.73; 95% CI: 1.03-2.911 for each 10% increase; p=0.038). CONCLUSIONS:In low risk AS patients, higher levels of fibrosis are independent predictors of all-cause death and the composite of all-cause death or non-fatal cardiovascular hospitalization. Further advances in anti-fibrotic therapies in AS are needed.