The target ablation index values for electrical isolation of the superior vena cava

The ablation index (AI), developed as a radiofrequency (RF) catheter ablation composite component endpoint, which incorporates contact force (CF), time, and power in a weighted formula, has been reported to be useful for a durable pulmonary vein isolation (PVI) to treat atrial fibrillation (AF). No study has reported the target AI value for the SVC isolation (SVCI). In this study, we aimed to investigate the target AI for the SVCI.

Thirty-six AF patients who underwent an initial SVCI were enrolled. Ablation was performed at 556 points. The sites where dormant conduction was induced or additional ablation was needed were defined as touch up sites (n = 36). We compared the energy deliver time, power, generator impedance (GI) drop, local bipolar voltage, contact force (CF), force-time integral (FTI), and AI between the touch up sites and the no touch up sites (n = 520).

The FTI and AI were significantly lower at the touch up sites (touch up sites vs. no touch up sites; FTI, 126.5 [99.3-208.8] vs. 244 [184-340.8], p < 0.0001; AI, 350.1 ± 43.6 vs. 277.2 ± 21.8, p < 0.0001). The median value of the AI at the no touch up sites was 350, and no reconnections were seen where the minimum AI value was more than 308. Most of the touch up sites were located in the anterior wall and lateral wall (anterior wall, 20/36 sites [55.6%]; lateral wall, 10/36 sites [27.8%]; septal wall, 6/36 sites [16.7%]; posterior wall, 0/36sites [0.0%]).

The target AI value for the SVCI should be 350, and at least 308 would be needed.