Main Findings
In the present study, we evaluated the incidence of SVC stenosis after SVC isolation. A contrast-enhanced CT scan obtained four months after the ablation yielded a 14% reduction in the SVC dimensions without any concomitant life-threatening symptom.
The quantitative assessment of the SVC area after the SVC isolation has not been investigated adequately until now. Arruda et al. reported that the SVC area changed from 2.83 ± 0.63 cm2 to 2.61 ± 0.76 cm2 following the SVC isolation in 68 AF patients.7 In that research, high-output pacing was performed (30 mA) before RF pulses were delivered at the posterolateral aspect of SVC to evaluate the diaphragmatic stimulation. The SVC isolation was aborted to avoid PNP in the case of diaphragmatic stimulation.6 Correspondingly, complete SVC isolation was achieved in 85% of the patients. In our cases, RF pulses (20 s, 20 W) were delivered circumferentially even at the phrenic nerve capture sites in the cases at which the SVC potential was maintained after the ablation process. All SVC isolation procedure were completed successfully without any acute complications.
Miyazaki et al.8 demonstrated the prevalence of the SVC reconnection after the first SVC isolation was observed in 74% of the studied patients. Moreover, Arruda et al. reported a 12% incidence of SVC triggers in a cohort of the 190 AF patients they studied.7 Based on these research studies, complete and durable SVC isolation is considered to improve the outcome of AF ablation even if the recent meta-analysis noted the controversy related to the additional benefits of empirical SVC isolation.9
In the previous studies, the SVC areas were evaluated only at three months after the ablation process. Therefore, SVC narrowing data after this timeframe is limited. In this study, in the six out of the eight narrowing cases, the SVC narrowing did not progress. SVC stenosis did not develop in any of the studied cases and there were no life-threatening symptoms. This means that the SVC stenosis which developed in subsequent time intervals did not seem to be of significant concern.