Clinical significance of tissue fibrosis and conduction abnormality in long-term prognosis in hypertrophic cardiomyopathy

Abstract

Purpose: This study evaluates the level of tissue fibrosis by RV biopsy in hypertrophic cardiomyopathy (HCM) patients and assessed its relevance to the long-term prognosis. Methods: Of 494 consecutive HCM patients, 194 patients histologically diagnosed were enrolled (58±13 years old). The amount of fibrosis (%-area) in tissue samples from RV biopsy were quantified and classified into mild ( 17%). Hemodynamic, echocardiographic and electrophysiological parameters were also evaluated. Patients were followed and primary endpoint was adverse cardiac events; heart failure or lethal ventricular arrhythmias, and secondary endpoint was death from any cause. Results: Degree of tissue fibrosis was associated with cellular diameter, LVEDP but not LVEF and BNP level. Patients with severe fibrosis had longer filtered QRS (fQRS), positive late potential by SAECG and positive fragmented QRS, resulting in a higher incidence of VT/VF. During 5±4 years follow-up, 92 (47%) patients had adverse cardiac events. The higher degree of fibrosis had a greater risk of following adverse events (Fig.1). Multivariate Cox analysis revealed that tissue fibrosis (>6%) and longer fQRS of SAECG had a greater risk of adverse cardiac events with hazard ratio: 2.01 (95% CI=1.02-4.20; p<0.05) and 1.11/10-ms (95% CI=1.03-1.19; p<0.01), respectively. Therefore, a scoring from severity of tissue fibrosis (0∼2) and filtered QRS duration (0∼2) was useful for risk stratification of adverse cardiac events in HCM (Fig.2). On the other hand, lower LVEF (p=0.008) and history of VT/VF (p=0.02) were the independent predictor for any cause of death. ![Figure][1] Cardiac events and tissue fibrosis Conclusion: Higher LVEDP-related fibrotic change may contribute to the abnormal conduction delay as well as spontaneous VT/VF, leading to poor prognosis in HCM patients. [1]: pending:yes