Results from left ventricular epicardial electrical mapping showed that, compared to sham-operated heart failure mice, the treatment group exhibited shorter ventricular activation time and lower activation heterogeneity (Figures 2A-2C). Left ventricular electrical pacing experiments demonstrated that the isochrones in sham-operated heart failure mice showed more pronounced bunching, whereas the isochrones in treated ACSL1TG mice and non-heart failure control mice were more dispersed (Figures 2D-2F). Isochrones are a graphical representation of conduction velocity, with wider isochrones indicating faster conduction and narrower, more densely packed isochrones indicating slower conduction. Although the difference did not reach statistical significance, a trend toward increased conduction velocity was observed after treatment (Figure 2G).

(A) Examples of sinus epicardial activation maps of 5 consecutive beats. (B) Sinus rhythm epicardial activation time (AT). Control (n = 4), Sham RT (n = 10), 5 Gy RT (n = 8). **P = 0.0054 (Control vs Sham RT), *P = 0.0356 (Sham RT vs 5 Gy RT). (C) Sinus rhythm epicardial activation time heterogeneity. Control (n = 4), Sham RT (n = 10), 5 Gy RT (n = 8). **P = 0.0051 (Control vs Sham RT). (D) Example of paced epicardial activation map of 5 consecutive beats. (E) Paced epicardial activation time. Control (n = 4), Sham RT (n = 10), 5 Gy RT (n = 8). ***P = 0.0005 (Control vs Sham RT), *P = 0.0335 (Control vs 5 Gy RT). (F) Paced epicardial activation heterogeneity. Control (n = 4), Sham RT (n = 10), 5 Gy RT (n = 8). **P = 0.0032 (Control vs Sham RT). (G) Epicardial conduction velocity. Control (n = 4), Sham RT (n = 10), 5 Gy RT (n = 8). (H) Example of arrhythmias 6 weeks’ posttreatment. (I) Premature ventricular contraction (PVC) count after norepinephrine injection. Control (n = 4), Sham RT (n = 9), 5 Gy RT (n = 7). *P = 0.0489 (Sham RT vs 5Gy RT). (J) Ventricular arrhythmogenicity index (Table 1). Control (n = 4), Sham RT (n = 9), 5 Gy RT (n = 7). *P = 0.0215 (Sham RT vs 5Gy RT). VA = ventricular arrhythmia; other abbreviations as in Figure 1.

JACC. Clinical electrophysiology (IF 7.7)

DOI:10.1016/j.jacep.2025.10.034