Assessment of the esophagogastric junction (EGJ) using the EGJ contractile integral (EGJ-CI) following per-oral endoscopic myotomy (POEM) in achalasia

Background: the esophagogastric junction contractile integral (EGJ-CI) is a novel high-resolution manometry (HRM) tool designed to assess EGJ barrier function. This study assessed whether changes in EGJ-CI values reflect a disruption of the EGJ in achalasia patients undergoing per-oral endoscopic myotomy (POEM). Methods: patients with HRM performed both before and after POEM were identified over a three year period and were compared to healthy controls. EGJ-CI was calculated using the St Louis method, where EGJ vigor is assessed independently of respiration and referenced to the gastric baseline. It is reported as mmHg.cm. Pre- and post-POEM EGJ-CI, conventional lower esophageal sphincter pressure (LESP) metrics (end expiratory LESP and mean basal LESP) and integrated relaxation pressure (IRP) were compared between groups. The correlation between EGJ-CI and conventional LESP metrics was also assessed and compared to controls. Results: fifteen achalasia patients (35.2 ± 2.5 years, 73% female) fulfilled the inclusion criteria and were compared to 20 healthy volunteers (26.6 ± 1.1 years, 50% female). The Eckardt score was significant lower after POEM (1.5 ± 0.3 vs 7.0 ± 0.5, p < 0.001). Baseline conventional LESP metrics, EGJ-CI and IRP were higher in achalasia cases compared to controls (p < 0.001). Both conventional LESP metrics and EGJ-CI decreased significantly following POEM (p < 0.001) and approximated the values recorded in controls (p = 0.1). However, IRP remained higher post-POEM compared to controls (p = 0.011). EGJ-CI correlated with conventional LESP metrics at baseline (Pearson’s r = 0.75-0.79; Spearman’s rho = 0.84-0.85, p < 0.001) and following POEM (0.55- 0.70 and 0.5-0.77, respectively; p = 0.03). Conclusions: EGJ-CI complements the assessment of the EGJ barrier and may be a useful metric to follow barrier function after per-oral myotomy.