Cardiac MRI-guided characterization of substrate in ventricular tachycardia ablation: a comparative meta-analysis of ischemic vs. non-ischemic cardiomyopathy

Abstract Background Patients with ischemic (ICM) and non-ischemic cardiomyopathy (NICM) undergoing catheter ablation for ventricular tachycardia (VT) present with distinct myocardial substrate characteristics. The role of cardiac imaging in differentiating procedural outcomes and substrate burden between ICM and NICM remains incompletely defined. Purpose This meta-analysis aims to clarify the differential impact of underlying cardiomyopathy etiology on ablation strategies, imaging-defined scar metrics, and procedural success, thereby informing patient-specific substrate-guided ablation planning. Methods A systematic literature search was conducted using PubMed, Embase and Cochrane databases for randomized controlled trials and observational studies comparing ICM and NICM in the context of VT ablation guided by cardiac magentic resonance (CMR). Primary outcome was left ventricular ejection fraction (LVEF). Secondary outcomes included VT non-inducibility post-procedure, use of epicardial approach, presence of late gadolinium enhancement (LGE) on CMR, extent of scar and border zone (BZ) mass, complete local abnormal ventricular activity (LAVA) elimination, and other procedural variables. Pooled effect sizes were calculated as mean differences (MD), odds ratios (OR), or standardized mean differences (SMD) with 95% confidence intervals (CI). Heterogeneity was evaluated with the I² statistic. Results Four observational studies were included, comprising 366 patients with ICM (62,2 %) and NICM undergoing VT ablation. LVEF was not significantly different between groups (MD: –2.15 %; 95% CI: –6.69 to 2.38; I² = 69% ; Figure 1). Presence of LGE on CMR did not differ significantly (OR: 1.29; 95% CI: 0.67–2.48; I² = 0% ; Figure 2). LGE-defined scar mass (SMD: 0.25 % ; 95% CI: –0.22 to 0.72; I² = 0% ; Figure 3) and BZ mass (SMD: 0.20 % ; 95% CI: –0.09 to 0.48; I² = 0% ; Figure 4) were comparable. Core scar mass trended higher in ICM but was not statistically significant (SMD: 0.58 g; 95% CI: –0.03 to 1.13; I² = 63% ; Figure 5). Epicardial ablation was significantly more frequent in NICM patients (OR: 0.04; 95% CI: 0.01–0.22; I² = 74% ; Figure 6). Non-inducibility of VT was similar across groups (OR: 0.60; 95% CI: 0.34–1.07; I² = 18% ; Figure 7). Complete LAVA elimination rates were similar (OR: 1.59; 95% CI: 0.76–3.32; I² = 0% ; Figure 8). Conclusion Despite differing underlying etiologies and scar patterns, procedural and imaging-based outcomes of VT ablation between ischemic and non-ischemic cardiomyopathy show broadly similar trends, with the exception of a significantly higher need for epicardial access in NICM. These findings highlight the importance of tailored substrate assessment and the role of imaging in guiding ablation strategy across cardiomyopathy subtypes.Figure 1.Forest Plots of Outcomes Figure 2.Forest Plots of Outcomes