Inclusion Criteria:  Complete and adequate HRM and pH-impedance study performed within 2 weeks Successfully performed SLR maneuver (adequate intra-abdominal pressure augmentation)  Exclusion Criteria:  Patients with prior foregut surgery Obese with BMI>35 Kg/m2 Paraesophageal hiatal hernia Scleroderma Eosinophilic esophagitis