GH after ablation
GH occurs as an adverse event of catheter ablation for AF due to thermal injury of the periesophageal nerves close to the LAPW.7 Yamasaki et al.18 reported excessive transmural injury in 5.8% of patients who underwent AF ablation using an RF catheter with additional LA roof line ablation, noting that body mass index may be a predictor of excessive transmural injury after ablation.
The prevalence of GH after CBA is reported to be 10.3–17.5%.7,11 Aksu et al.7 found that the prevalence of GH was higher in the CBA group; however, GH was generally reversible after CBA, compared with RF ablation, and the nadir temperature during CBA for inferior PVs and smaller LAD was associated with GH in the CBA group. Miyazaki et al.11demonstrated that GH after CBA occurred in cases in which the esophagus was located between the LAPW and thoracic spine, or in those in which the distance between the RIPV and esophagus was short. In our study, CBA of the LA roof was performed in addition to PVI; however, the prevalence of GH after ablation was not as high as previously reported. This result may be attributed to the therapeutic strategy of avoiding the ablation of the LAPW such as the LAPW bottom line. In our study, LAD was significantly smaller in patients with GH, as previously reported. Given that RIPV diameter was also smaller in those with GH, a cryoballoon may be apt to contact the broader area of the LAPW during PVI, which may cause periesophageal nerve injury. However, our multivariate analysis indicated that LA roof height from the point of contact between the LAPW and esophagus can predict GH after CBA. During CBA of the LA roof, the cryoballoon contacts both the LA roof and part of the LAPW; namely, cryothermal energy conducts the LAPW close to the esophagus, especially in patients with lower LA roof height. This may explain the findings predictive of GH in our study.
Several studies have also examined the relationship between LET and esophageal complications. Kuwahara et al.5 reported that RF applications under LET monitoring may reduce the incidence of GH; indeed, conventional PVI using an RF catheter is generally performed under LET monitoring. Additionally, Fürnkranz et al.4demonstrated that LET-guided CBA with a cutoff value of 15°C was associated with a lower incidence of esophageal lesions. In contrast, Miyazaki et al.11 reported that LET monitoring was not related to the incidence of esophageal complications after CBA for PVI; instead, the incidence of esophageal lesions increased when an esophageal probe was used.
In this study, we performed CBA under LET monitoring. First, although CBA of the LA roof was additionally performed, LET reached 15°C most frequently during PVI. Second, although no significant difference was observed, the percentage of patients in whom LET reached 15°C, especially during LA roof line ablation, was higher in those with GH than in those without. Moreover, LET during CBA of the LA roof reached 15°C more frequently when LA roof height was lower, or when the distance between the LA roof and esophagus was shorter. If CBA were performed without LET monitoring, the incidence of GH may have differed.
Although GH is detected via esophagogastroscopy in patients undergoing catheter ablation for AF, not all cases are symptomatic. Hasegawa et al.8 reported that the incidence of symptomatic GH after CBA for PVI was 3.0%; however, as the degree of symptoms associated with GH may be slight in some cases, the incidence of symptomatic GH may be underestimated.
Lakkireddy et al.6 reported that mean PAGI-SYM scores significantly increased from 7.8% to 15.6% 24 hours after ablation, with higher scores in patients with abnormal gastrointestinal functional test results. In our study, PAGI-SYM scores did not increase 1 day after ablation; however, they significantly increased 1 week after ablation in patients with GH. Although the scores were lower in our study than previously reported, patients may suffer from mild GH-related symptoms that appear a while after ablation.