Distribution of Myocardial Fibrosis in Patients with Non-Ischemic Cardiomyopathy and Ventricular Tachycardia Based on Genetic Variant.

ABSTRACT

BACKGROUND: Many genetic non-ischemic dilated cardiomyopathies (NICM) cause ventricular tachycardias (VT) originating from scar substrate identified as areas of low electrogram voltage. Substrate locations vary and the causes of scar are not well defined. OBJECTIVE: This study evaluated VT substrate locations in genetic NICM patients undergoing VT ablation to evaluate spatial relationships between specific variants and substrate locations. METHODS: In this retrospective case series analysis, 32 patients (age 55 +/- 16 years, 94% male, left ventricular ejection fraction 34 +/- 13%) with genetic NICM referred for VT ablation between October 2018 and November 2022 at a single medical center were evaluated. Scar locations were defined as areas of low unipolar/ bipolar voltage. RESULTS: Of the thirty-two patients evaluated, mutations in TTN (n=11 of 32), LMNA (n=6 of 32), PKP2 (n=5 of 32), MYBPC3 (n=3 of 32), DSP (n=2 of 32), TTR (n=1 of 32), FLNC (n=1 of 32), AGL (n=1 of 32), DES (n=1 of 32), DSG2 (n=1 of 32), were observed. Substrates associated with mutations in TTN were only observed in basal subregions, predominantly anterior (100%), and septal (50%) regions. LMNA mutations were associated with fibrosis in mid inferolateral (60%) and apical inferolateral (60%) regions. Substrate location for individuals with PKP2 mutations were solely observed in the right ventricle, predominantly basal inferolateral regions. CONCLUSION: Understanding spatial relationships between genetic variants causing NICM and VT substrate locations can help lead to generalizable regions in patients with genetically related NICM presenting in VT which can be investigated during ablation procedures.