Each group showed a significantly different (P less than .01) pattern of mucosal impedance (MI), or disruption of mucosal integrity, along the esophageal axis, wrote Dhyanesh A. Patel, MD, of Vanderbilt University Medical Center in Nashville, Tenn., and his associates. Patients without GERD had higher MI values along all esophageal segments, while GERD was characterized by below-normal values in the distal esophagus only, and eosinophilic esophagitis led to low values throughout the esophagus.
The findings were validated in a separate patient cohort, and the only reported adverse event was an episode of mild chest pain. “This contour heatmap could easily be employed to establish a diagnosis during endoscopy, independent of biopsy or pH monitoring,” the investigators wrote in. They cautioned that the balloon catheter cannot be safely used in patients with severe fibrostenotic disease.
Current definitive diagnostics for GERD leave much to be desired. Transnasal probes are imprecise and uncomfortable, and they can be insensitive if discomfort causes patients to vary normal activity or skip meals. Wireless ambulatory pH monitoring is more tolerable but unreliable and measures only acidity of refluxed material at a single point along the esophagus. These tests also “fail to account for day-to-day variability of reflux, as they only provide a 24- to 48-hour snapshot of a disease process that is chronic in nature,” the researchers wrote. Eosinophilic esophagitis is becoming more common and usually requires proximal and distal biopsies for diagnosis.
Mucosal impedance contour pattern testing is based on the fact that both GERD and eosinophilic esophagitis involve increased distance between esophageal epithelial cells. The amount of intercellular dilatation correlates inversely with MI values. In proof-of-concept studies, individuals with GERD, non-GERD, eosinophilic esophagitis, and achalasia had distinct MI patterns. However, these studies tested a single-channel catheter system that took only point measurements and was subject to interoperator variability. To improve on this concept, Dr. Patel and his associates mounted radial and axial sensors on a balloon catheter to measure MI at 180-degree intervals along a 10-cm esophageal segment.
They tested the new device prospectively in 69 patients undergoing esophagogastroduodenoscopy with or without pH monitoring (which was used as the standard). In all, 24 patients had GERD, 21 had eosinophilic esophagitis, and 24 had normal findings. By using the intercept and slope of the balloon MI measurements, the researchers detected GERD with an area under the receiver operating characteristic curve (AUC) of 0.67, eosinophilic esophagitis with an AUC of 0.84, and non-GERD with an AUC of 0.83.
These findings held up in a separate validation cohort of 36 patients (28 with GERD and eight with eosinophilic esophagitis) from three tertiary care centers. The probability of eosinophilic esophagitis was highest in patients with low distal MI values (that is, a low intercept) and a low slope (showing that MI values remained low proximally). A low distal MI intercept with a steeper positive slope suggested GERD, while a higher distal MI intercept with a steep slope signified non-GERD.
The system “potentially obviates the need for 24- to 48-hour ambulatory wireless pH monitoring or esophageal biopsies for histopathology,” the researchers concluded. “This can help reduce diagnostic and treatment latency and might allow for monitoring disease activity over time.”
The National Institutes of Health funded the external validation analysis. Diversatek Healthcare, which patented the device together with Vanderbilt University, gave research funding to four coinvestigators, including the senior author. Dr. Patel and the other five coinvestigators reported having no conflicts of interest.
SOURCE: Patel DA et al. Gastroenterology. 2019 Jan 31. .