Septal late enhancement by cardiac CT is associated with repeat ablation in nonischemic cardiomyopathy patients.

Introduction: Scar substrate in nonischemic cardiomyopathy (NICM) patients is often difficult to identify. Advances in cardiac imaging, especially using late iodine-enhanced computed tomography (LIE-CT), allow better characterization of scars giving rise to ventricular tachycardia (VT). Currently, there are limited data on clinical correlates of CT-derived scar substrates in NICM. We sought assess the relationship between scar location on LIE-CT and outcomes after radiofrequency catheter ablation (RFCA) in NICM patients with VT.

Methods: From 2020 to 2022, consecutive patients with NICM undergoing VT RFCA with integration of cardiac CT scar modeling (inHeart, Pessac, France) were included at two US tertiary care centers. The CT protocol included both arterial-enhanced imaging for anatomical modeling and LIE-CT for scar assessment. The distribution of substrate on CT was analyzed in relation to patient outcomes, with primary endpoints being VT recurrence and the need for repeat ablation procedure.

Results: Sixty patients were included (age 64 ± 12 years, 90% men). Over a median follow-up of 120 days (interquartile range [IQR]: 41-365), repeat ablation procedures were required in 32 (53%). VT recurrence occurred in 46 (77%), with a median time to recurrence of 40 days (IQR: 8-65). CT-derived total scar volume positively correlated with intrinsic QRS duration (r = .34, p = 0.008). Septal scar was found on CT in 34 (57%), and lateral scar in 40 (7%). On univariate logistic regression, septal scar was associated with increased odds of repeat ablation (odds ratio [OR]: 2.9 [1.0-8.4]; p = 0.046), while lateral scar was not (OR: 0.9 [0.3-2.7]; p = 0.855). Septal scar better predicted VT recurrence when compared to lateral scar, but neither were statistically significant (septal scar OR: 3.0 [0.9-10.7]; p = 0.078; lateral scar OR: 1.7 [0.5-5.9]; p = 0.391).

Conclusion: In this tertiary care referral population, patients with NICM undergoing VT catheter ablation with septal LIE-CT have nearly threefold increased risk of need for repeat ablation.