Proximal esophageal impedance baseline increases the yield of impedance-pH monitoring for GERD diagnosis and is associated with heartburn response to PPI.

BACKGROUND: Impairment of esophageal mucosal integrity as assessed by low mean nocturnal baseline impedance (MNBI) measured in the distal esophagus increases the diagnostic yield of impedance-pH in patients with inconclusive GERD diagnosis as defined by Lyon criteria. AIM: To assess the diagnostic yield of MNBI measurement in the proximal esophagus, and its relationship with PPI response. METHODS: Expert review of off-therapy impedance-pH tracings from consecutive patients with heartburn, 80 responders and 80 non-responders to label-dose PPI. Data were compared to those from 36 healthy controls using ROC analysis. Multivariate analysis was performed to measure the strength of association of MNBI with PPI response. RESULTS: A threshold value of 2665 Ω was defined for proximal MNBI by ROC analysis, affording 91.7% sensitivity and 86.5% specificity. Proximal and distal MNBI were significantly lower in non-responder cases as compared to responders. Adding proximal MNBI positivity to pathologic (>6%) acid exposure time (AET) and positive symptom-reflux association, the proportion of patients with abnormal impedance-pH findings increased from 74/160 (46%) to 106/160 (66.3%) (p = 0.0016). Among the 12 patients with pathologic proximal MNBI as the only positive impedance-pH finding, 9 cases (75%) were PPI responders. According to multivariate analysis, AET and pathological distal and proximal MNBI were significantly associated with PPI response, the strongest association observed for proximal MNBI. CONCLUSIONS: Impedance baseline assessment in the proximal esophagus may increase the diagnostic yield of impedance-pH monitoring. Heartburn response to PPI is directly related to ultrastructural mucosal damage in the distal and in the proximal esophagus as well.