A) Esophageal Complications
The proximity of the esophagus to the posterior wall of the left atrium
(LA) limits power delivery and hence the quality of lesion. There is no
consensus on the best RF setting to create effective transmural lesions
on the posterior wall while minimizing risk of esophageal thermal
injury. Conventionally, the preferred ablation strategy over the
posterior wall is a low power setting (ranging from 20-30 W). However,
several studies have shown safety of HPSD technique with regards to
esophageal complications. In a study utilizing late gadolinium
enhancement magnetic resonance imaging (LGE MRI) to assess extent and
persistence of esophageal thermal injury post AF ablation, moderate to
severe esophageal enhancement was seen in 14.3% patients undergoing AF
ablation with both HPSD (50 W/ 5 s) and LPLD (<35 W for 10 to
30 s) ablation strategies on same day LGE MRI.32 There
were no atrioesophageal fistulas noted even with use of CF catheters in
the HPSD group underlining the importance of appropriate titration of
ablation parameters on the posterior wall (i.e., short duration of 5 s
or less, and reduced CF on the posterior wall to 10 to 15
g).32 Posterior wall applications using 45-50 W for
2-10 s have been noted to be safe in a multicenter study by Winkle et
al.31 In a study including 10,284 patients from 4
experienced centers, 1 atrioesophageal fistula (0.0087%) occurred in
11,436 HPSD ablations performed using 45–50 W for 2-10 s on the
posterior wall, while 3 atrioesophageal fistulas (0.12%) occurred in
2,538 LPLD ablations using 35 W on the posterior wall for 20 s (p =
0.021). Notably, the researchers reported that 2 of the 3
atrioesophageal fistulas in the 35 W group did not undergo esophageal
temperature monitoring. In another retrospective study including 76 AF
patients, there was a trend towards less esophageal heating with HPSD
technique (45 W for 6 s on the posterior wall with CF 8-15 g & 50 W for
6 s on the anterior wall with CF 10-20 g) compared to LPLD technique (30
W for 30 s with CF 10-30 g) with the incidence of esophageal heating
being 51.2% in the HPSD group and 74.3% in the LPLD group (p =
0.0578).30