Abstract 13544: Tissue Fibrosis of Myocardial Biopsy as a Novel Predictor for Adverse Cardiac Events in Patients With Hypertrophic Cardiomyopathy
Background and aim: This study sought to evaluate the level of tissue fibrosis by right ventricular (RV) biopsy in hypertrophic cardiomyopathy (HCM) patients and to assess its relevance to the long-term prognosis. We hypothesized that myocardial fibrosis in HCM plays a critical role in major adverse events such as ventricular tachyarrhythmias (VT/VF) or heart failure.
Methods: Of 494 consecutive HCM patients, 185 histologically diagnosed patients were enrolled (58 ± 14 years old). The amount of fibrosis (% area) was quantified using a digital microscope and classified into three degrees: mild (<10%), moderate (10-20%), and severe (>20%). Hemodynamic, echocardiographic, and electrophysiologic parameters were also evaluated.
Results: The degree of tissue fibrosis was associated with left ventricular end-diastolic pressure (LVEDP) but not maximum LV wall thickness, LV ejection fraction (LVEF), or brain natriuretic peptide (BNP) level. Signal-averaged electrocardiogram (SAECG) revealed that patients with severe fibrosis had longer QRS duration and positive late potential (LP), resulting in a higher incidence of VT/VF. At the 5 ± 4-year follow-up, 86 (46%) patients had had adverse cardiac events (heart failure or VT/VF). Lethal arrhythmic events(VT/VF) and adverse cardiac events were both associated with tissue fibrosis(Figure A). Multivariate Cox regression analysis results revealed that tissue fibrosis and positive LP of SAECG led to a greater risk of adverse cardiac events (HR 1.03/% and 4.76, p<0.05 and p<0.001, respectively). Therefore, scoring the severity of tissue fibrosis and positive LP was useful for the risk stratification of adverse cardiac events in HCM patients (Figure B).
Conclusion: Myocardial fibrosis in RV biopsy tissues samples may contribute to abnormal conduction delay and spontaneous VT/VF, leading to a poor prognosis in HCM patients.
- © 2013 by American Heart Association, Inc.