Integrated Relaxation Pressure (IRP) Distinguishes between Reflux-Predominant and Dysphagia-Predominant Phenotypes of Esophageal "Absent Contractility".

Abstract

Patients with absent contractility (AC) often suffer from either reflux or dysphagia. It remains unclear what factors determine which phenotype patients present with. We sought to evaluate if high-resolution manometry metrics, especially integrated relaxation pressure (IRP), could explain this. Cases of AC from three medical centers were reviewed for demographic, clinical, and manometric data. Cases with an IRP between 10-15 mmHg or subsequent diagnosis of achalasia were excluded. 69 subjects were included (mean age 56.1; 71% female). A total of 41 (59.4%) were reflux-predominant. The reflux-predominant group was younger (51.1 vs. 63.5, p = 0.002) and had lower median LES basal pressures (7.5 vs. 12.5 mmHg, p = 0.014) and IRP values (1.5 vs. 5.6 mmHg, p < 0.001) compared to the dysphagia group. When divided into tertiles, the trend in symptoms between LES basal pressure tertiles was not significant. However, the trend for IRP was significant (p < 0.001). For example, in the lowest IRP tertile, 91.3% of subjects were reflux-predominant compared to only 26.1% in the highest tertile, while the dysphagia-predominant group increased from 8.7% to 73.9%. In a regression model controlling for age and using IRP tertile 1 as the reference, having an IRP in tertile 2 increased the likelihood of having dysphagia-predominant disease by 7, while being in tertile 3 increased the likelihood by 22. IRP helps distinguish between the reflux-predominant and dysphagia-predominant phenotypes of AC. This may have therapeutic clinical consequences as procedures such as fundoplication to tighten the LES may benefit patients with reflux and a low IRP, while procedures like peroral endoscopic myotomy (POEM) to disrupt the LES may benefit patients with dysphagia and a relatively high IRP.