ABSTRACT
OBJECTIVES: Often 2-3 graduated pneumatic dilatations (PD) are required to treat achalasia as there is no current intra-procedural predictor of clinical response. Distensibility measurements using functional lumen imaging probe (FLIP) may provide an intra-procedural predictor of outcome. Our aim was to determine the optimal criterion for esophagogastric junction (EGJ) distensibility measurements during PD that predicts immediate clinical response. METHODS: EGJ distensibility was prospectively measured using FLIP immediately pre- and post-PD. The EGJ distensibility index (EGJ-DI) was defined as a ratio of the narrowest cross-sectional area and the corresponding intra-bag pressure at 40 ml distension. Immediate and short-term clinical responses were defined as Eckardt score ≤3 assessed 2 weeks Post-PD and at 3-month follow-up, respectively. RESULTS: In 54 patients, we performed thirty-seven 30 mm; twenty 35 mm and six 40 mm PDs. The short-term response rate to the graded PD was 93% (27/29) in newly diagnosed achalasia; 87% (13/15) and 70% (7/10) in those who had relapsed after previous PD and Heller's Myotomy, respectively. Among those demonstrating an immediate response, EGJ-DI increased by an average of 4.5 mm2/mmHg (95% CI (3.5, 5.5) (P<0.001). Within-subject Δ EGJ-DI was highly predictive of immediate clinical response with AUROC of 0.89 (95% CI [0.80, 0.98], P<0.001). An increment in EGJ-DI of 1.8 mm2/mmHg after a single PD predicts an immediate response with an accuracy of 87%. CONCLUSIONS: FLIP-measured Δ EGJ-DI is a novel intra-procedural tool that accurately predicts immediate clinical response to PD in achalasia. This technique may potentially dictate an immediate mechanism to "step-up" dilator size within a single endoscopy session.