474. MANOMETRIC IDENTIKIT OF A FUNCTIONING AND EFFECTIVE FUNDOPLICATION IN THE HIGH-RESOLUTION MANOMETRY ERA

Assessing patients following Laparoscopic Fundoplication (LF) can be challenging. Functional information provided by pathophysiological testing—which can shed light on the cause of recurrent symptoms—could be key to clinical decision making. The value of performing High-Resolution Manometry (HRM) after LF is still unclear and debated. We sought to establish the HRM parameters indicative of a functioning fundoplication, and whether HRM could distinguish it from a tight or defective one. We studied patients with gastroesophageal reflux disease (GERD) who underwent laparoscopic Nissen (LN) or Toupet (LT) fundoplication between 2010–2022. HRM and pH monitoring were performed before and 6 months after surgery. LF failure was defined as GerdQ score ≥ 8 and abnormal 24 h-pH study or just abnormal 24 h-pH study. The study population was divided into 5 groups: LN and LT patients with normal pH monitoring (LNpH- and LTpH-, respectively); LN and LT patients with pathological pH monitoring (LNpH+ and LTpH+ groups, respectively); and patients with postoperative severe dysphagia (Dysphagia group). The novel Hiatal Morphology (HM) classification was applied, envisaging 3 subtypes: HM1 (normal morphology); HM2 (intrathoracic fundoplication); and HM3 (slipped fundoplication). We recruited 132 patients: 46 in the LNpH- group, 51 in the LTpH- group, 15 in the LNpH+ group, 7 in the LTpH+ group, and 5 in the Dysphagia group (Figure 1). Eight patients with GerdQ score ≥ 8 and normal 24 h-pH findings were excluded. At univariate analysis, postoperative lower esophageal sphincter (LES) basal pressure (p = 0.011), total and abdominal LES length (p = 0.014, p < 0.001) were correlated with LF failure. At multivariate analysis, postoperative abdominal LES length (p = 0.001) and HM2 (p < 0.001) were independently associated with surgical failure. Integrated relaxation pressure (IRP) was significantly higher in the Dysphagia group than in the LNpH- group. This study generated reference HRM values for an effective LF and confirms that using HRM to assess the abdominal portion of the neo-sphincter and abnormal hiatal morphology (HM2) improves the clinical assessment of recurrent symptoms. HRM can distinguish patients with a well-functioning wrap from those developing recurrent GERD due to an ineffective wrap. Postoperative IRP also correlated significantly with the onset of dysphagia after surgery.