B-PO03-169 MYOCARDIAL SCAR BURDEN QUANTIFIED BY CARDIAC MAGNETIC RESONANCE IMAGING IS PREDICTIVE OF VENTRICULAR TACHYCARDIA IN PATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY

Abstract

Patients with hypertrophic cardiomyopathy (HCM) are at a higher risk of developing ventricular tachycardia (VT) and sudden cardiac death (SCD). Previous studies have demonstrated a correlation between late gadolinium enhancement (LGE) measured by cardiac magnetic resonance imaging (MRI) quantified as % of myocardial mass and VT; however, the predictive value of a more practical and routinely performed semi-quantitative assessment of LGE remains unknown. To determine whether a semi-quantitative assessment of myocardial fibrosis by cardiac MRI (number of myocardial segments with LGE) is predictive of VT in patients with HCM. We identified 65 patients (mean age 47±17, 34% female) with a clinical diagnosis of HCM who had a cardiac MRI prior to an implantable cardioverter defibrillator (ICD) implantation for primary prevention of SCD. VT was defined as appropriate anti-tachycardia pacing or shocks for sustained ventricular arrhythmias. The MRI was analyzed by an experienced radiologist blinded to the clinical data. LGE was assessed by both quantitative (% of total myocardial mass) and semi-quantitative (number of myocardial segments involved) methods. During the follow-up period (median 33 months), seven patients experienced VT. Patients with > 6 myocardial segments with LGE were at higher risk to develop VT (OR: 5.7, p=0.03) which remained significant after adjusting for age, maximum left ventricular wall thickness, left atrial size, maximum left ventricular outflow gradient, history of nonsustained VT, unexplained syncope, and family history of SCD (p=0.03). Similarly, patients with a higher fibrosis burden (LGE >10% myocardial mass) were more likely to develop VT (OR: 8.6, p=0.01) even after adjusting for the abovementioned traditional risk factors (p=0.04). The extent of LGE, assessed by both quantitative and semi-quantitative measures, is strongly associated with ventricular arrhythmias requiring ICD therapy in patients with HCM even after accounting for traditional risk factors. Fibrosis burden as detected by cardiac MRI may serve as an imaging biomarker to improve risk stratification and patient selection for primary prevention ICD implantation in patients with HCM.