Valvular cardiomyopathy in aortic valve regurgitation correlates with myocardial fibrosis

Abstract

Abstract Objective At the tissue level, disruption of the extracellular matrix network leads to irreversible cardiac fibrosis, which contributes to myocardial dysfunction. At the myocyte level, downregulation of beta-adrenoceptors (beta-AR) reduces adapation to increased workload. The aim of our study was to analyse the correlation between myocardial fibrosis and beta-AR sensitivity in patients with aortic valve (AV) disease. Methods A total of 92 consecutive patients who underwent elective AV surgery between 2017-2019 were included in our study (51 with aortic regurgitation(AR-group);41 with aortic stenosis(AS-group) and left ventricular (LV) biopsies were obtained intraoperatively. In-vitro force contractility testing was performed by measuring beta-AR sensitivity (–log EC50[ISO]). In parallel, quantitative analysis of myocardial fibrosis burden was performed. Results Mean age at the time of AV surgery was not statistically different in both groups (AR:53.3±15.3 years vs. AS:58.7±17.0 years;p=0.116). LV end-diastolic diameter was significantly enlarged in AR compared to AS-group (59.4±15.6 vs 39.7±21.2;p<0.001). Analysis of beta-AR sensitivity (AR:-6.769 vs. AS:-6.659;p=0.316) and myocardial fibrosis (AR:8.9% vs AS:11.3%;p=0.284) showed no significant differences between patients with AS and AR. There was no correlation between myocardial fibrosis and beta-AR sensitivity in the whole study cohort (R=0.1987;p=0.100) and in the AS-subgroup (R=0.009;p=0.960). However, significant correlation of fibrosis and beta-AR sensitivity was seen in AR-patients (R=0.363;p=0.023). Conclusion More severe myocardial fibrosis was associated with reduced beta-AR sensitivity in patients presenting with AR but not with AS. Therefore, our results suggest that in patients with AR, cellular myocardial dysfunction is present and correlates with the extent of myocardial fibrosis in the myocardium.