Value of genotyping and scar‐phenotyping for VT ablation procedures in patients with nonischemic left ventricular cardiomyopathies

Introduction: Variants of cardiomyopathy genes in patients with nonischemic
cardiomyopathy (NICM) generate various phenotypes of cardiac scar and delayed
enhancement cardiac magnetic resonance (DE‐CMR) imaging which may impact
ventricular tachycardia (VT) management.
Methods: The objective was to compare the findings of cardiomyopathy genetic
testing on DE‐CMR imaging and long‐term outcomes among patients with NICM
undergoing VT ablation procedures. Image phenotyping and genotyping were
performed in a consecutive series of patients referred for VT ablation and correlated
to survival free of VT. Scar depth index (SDI) (% of scar at 0‐3 mm, 3‐5 mm and
>5 mm projected on the closest endocardial surface) was determined.
Results: Forty‐three patients were included (11 women, 55 ± 14 years, ejection
fraction (EF) 45 ± 16%) and were followed for 3.4 ± 2.9 years. Pathogenic variants
(PV) were identified in 16 patients (37%) in the following genes: LMNA (n= 5), TTN
(n= 5), DSP (n= 2), AMLS1 (n= 1), MYBPC3 (n= 1), PLN (n = 1), and SCN5A (n= 1). A
ring‐like septal scar (RLSS) pattern was more often seen in patients with pathogenic
variants (66% vs 15%, p = .001). RLSS was associated with deeper seated scars
(SDI >5 mm 30.6 ± 22.6% vs 12.4 ± 16.2%, p = .005), and increased VT recurrence
(HR 5.7 95% CI[1.8‐18.4], p = .003). After adjustment for age, sex, EF, and total scar
burden, the presence of a PV remained independently associated with worse
outcomes (HR 4.7 95% CI[1.22‐18.0], p = .02).
Conclusions: Preprocedural genotyping and scar phenotyping is beneficial to identify
patients with a favorable procedural outcome. Some PVs are associated with an intramural, deeper seated scar phenotype and have an increase of VT recurrence
after ablation.