Changes in impedance planimetry (EndoFLIP) measurements at follow-up after peroral endoscopic myotomy (POEM)

Numerous studies show changes in functional lumen imaging probe (FLIP) measurements after myotomy during peroral endoscopic myotomy (POEM), but few report on FLIP measurements at follow-up esophagogastroduodenoscopy (EGD). The purpose of this study was to compare perioperative FLIP measurements to those at follow-up EGD.

Patients who underwent POEM with FLIP in the operating room and POEM patients who had EGD with FLIP at follow-up were included. FLIP measurements, including diameter (Dmin), pressure, cross-sectional area (CSA), and distensibility index (DI), were analyzed at a 30-mL balloon fill. Differences between measurements at different timepoints were assessed using a two-tailed Wilcoxon signed-rank test.

A total of 97 patients who underwent POEM and 28 who underwent EGD with FLIP were analyzed. The average age was 63 ± 18 years and 46.4% of the patients were male. Mean preoperative Eckardt score was 6.5 ± 4.8, decreasing to 1.6 ± 2.0 at follow-up. EGDs were performed at a median of 15 months after surgery. When compared to mean measurements obtained post-myotomy, at the time of EGD, pressure was found to be significantly lower (p = 0.007) and DI significantly higher (p = 0.045). Of the patients who underwent EGD, 70.8% had an increase in DI, 55.6% had evidence of reflux esophagitis, and 81.0% met diagnostic criteria for reflux on esophageal pH monitoring. However, there was no correlation with the development of esophagitis or reflux and increase or decrease in DI at follow-up.

There are significant changes in FLIP measurements between the time of surgery and at follow-up EGD. These results suggest that esophageal remodeling may cause changes in lower esophageal sphincter geometry after POEM and postoperative FLIP targets immediately post-myotomy may need to be adjusted to account for these changes.