LAS VEGAS – Functional lumen imaging probe (FLIP) was equivalent to high-resolution manometry (HRM) in predicting clinical response by Eckardt score 6 months or more after per oral endoscopic myotomy (POEM) for achalasia or esophagogastric junction (EGJ) outlet obstruction (EGJOO).
Measures for clinical response following lower esophageal sphincter myotomy procedures include Eckardt Score, timed barium esophagram, HRM, and FLIP. However, since FLIP is a relatively new technique, there are few clinical data comparing its efficacy versus HRM in patients who have a positive response to POEM measured by the Eckardt score, according to John DeWitt, MD, who presented the research at the annual meeting of the American College of Gastroenterology.
FLIP can be performed during a follow-up endoscopy while a patient is sedated, while HRM requires the patient to be awake. Some patients find the procedure intolerable, and Dr. DeWitt estimates that 10%-20% of patients don’t return for follow-up assessments because of the discomfort.
“[FLIP] is a relatively new technology, the role of which is still being discovered. We have a lot more information on the diagnosis side of things. The role in follow-up, particularly after myotomy, is really not defined well. This is the first study to my knowledge that has evaluated manometry and FLIP head-to-head to compare patient-reported outcomes,” said Dr. DeWitt in an interview. He is a professor of medicine and the director of endoscopic ultrasound at Indiana University Medical Center, in Indianapolis.
The researchers conducted a retrospective, single-center study of 265 consecutive patients who underwent POEM for achalasia or EGJOO from 2016 through 2020. A clinical response was defined as an Eckardt score ≤3, EGJ distensibility index (EGJ-DI) higher than 2.8 mm2/mm Hg, maximum integrated relaxation pressure (IRP) <15 mm Hg, or a maximum EGJ diameter greater than 14 mm at any balloon distension.
In all, 126 patients returned for follow-up and completed an upper endoscopy with FLIP, HRM, and Eckardt scores within a 6-12 month period after the POEM procedure.
With respect to HRM, an IRP measurement <15 mm Hg predicted post-POEM Eckardt score with a sensitivity of 86.7% (95% confidence interval, 79.3-92.2) and a specificity of 33.3% (95% CI, 4.3-77.7), with an area under the curve of 0.60 (95% CI, 0.39-0.81). A maximum EJG diameter ≥ 14 mm had a sensitivity of 77.5% (95% CI, 69.0-84.6) and a specificity of 33.3% (95% CI, 4.3-77.7), with an AUC of 0.55 (95% CI, 0.34-0.76).
The performance was similar with FLIP: EGJ-DI > 2.8 mm2/mm Hg at any balloon setting had a sensitivity of 95.0% (95% CI, 89.4-98.1) and a specificity% of 0.0, and an AUC of 0.53 (95% CI, 0.51-0.55). A similar measurement at 40 mL or 50 mL distension had a sensitivity of 93.3% (95% CI, 87.3-97.1) and a specificity of 16.7% (95% CI, 0.4-64.1), with an AUC of 0.55 (95% CI, 0.39-0.72). Receiver operator characteristic analysis showed no significant difference between ability of FLIP and HRM to predict a normal Eckardt score.
If the study is repeated in other patient populations, Dr. DeWitt hopes that it could eliminate manometry altogether in a large majority of patients. “That would be potentially a game changer for bringing patients back to see how well they’re doing,” said Dr. DeWitt.
Not all patients who undergo POEM would be good candidates for FLIP, said Dr. DeWitt. The study was limited to patients with hypertension in the lower esophageal sphincter. Other disorders such as diffuse esophageal spasm, jackhammer esophagus, and type III achalasia would not likely be candidates for FLIP. “Those patients are going to probably still need manometry because if the esophageal body abnormalities are still present, then repeat testing might need to be performed,” said Dr. DeWitt. Still, he estimated about 80% of patients could be eligible for FLIP instead.