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.