Esophageal baseline impedance levels in patients with pathophysiological characteristics of functional heartburn.

Abstract Background: Recently, it has been suggested that low esophageal basal impedance may reflect impaired mucosal integrity and increased acid sensitivity. We aimed to compare baseline impedance levels in patients with heartburn and pathophysiological characteristics related to functional heartburn (FH) divided into two groups on the basis of symptom relief after proton pump inhibitors (PPIs). Methods: Patients with heartburn and negative endoscopy were treated with esomeprazole or pantoprazole 40mg daily for 8weeks. According to MII-pH (off therapy) analysis, patients with normal acid exposure time (AET), normal reflux number, and lack of association between symptoms and refluxes were selected; of whom 30 patients with a symptom relief higher than 50% after PPIs composed Group A, and 30 patients, matched for sex and age, without symptom relief composed Group B. A group of 20 healthy volunteers (HVs) was enrolled. For each patient and HV, we evaluated the baseline impedance levels at channel 3, during the overnight rest, at three different times. Key Results: Group A (vs Group B) showed an increase in the following parameters: mean AET (1.40.8% vs 0.5 +/- 0.6%), mean reflux number (30.4 +/- 8.7 vs 24 +/- 6.9), proximal reflux number (11.1 +/- 5.2 vs 8.2 +/- 3.6), acid reflux number (17.9 +/- 6.1 vs 10.7 +/- 6.9). Baseline impedance levels were lower in Group A than in Group B and in HVs (p<0.001). Conclusions & Inferences: Evaluating baseline impedance levels in patients with heartburn and normal AET could achieve a better understanding of pathophysiology in reflux disease patients, and could improve the distinction between FH and hypersensitive esophagus