Muscular thickness of lower esophageal sphincter and therapeutic outcomes in achalasia: A prospective study using high‐frequency endoscopic ultrasound

Abstract Background and Aim Patients with achalasia typically have thicker lower esophageal sphincter muscles, which can affect the distensibility of the esophagogastric junction. We aimed to assess whether these muscular features, measured using high‐frequency endoscopic ultrasound, affect treatment outcomes. Methods Consecutive adult patients with suspected achalasia were enrolled prospectively. They underwent a comprehensive diagnostic workup, including endoscopic ultrasound. The thickness of the lower esophageal sphincter, including the internal circular and outer longitudinal muscles, was measured using a 12‐MHz ultrasonic miniprobe. Follow‐up was performed at 1 month and then at 6‐month intervals, after treatment. Treatment response was defined as a reduction in Eckardt score to ≤3 or an improvement in the height of the timed barium esophagogram of ≥50%. Results Of the 29 patients who received pneumatic dilatation, all but one (96.6%) exhibited a good short‐term treatment response. At an average follow‐up time of 18.5 (12–55.5) months, patients who had a mid‐term recurrence after pneumatic dilatation had a significantly thicker outer longitudinal muscle (1.8 [1.5–1.8] vs 0.9 [0.8–1.7] mm, P = 0.036), but not internal circular muscle (2.0 [1.9–2.5] vs 2.1 [1.2–2.7] mm, P = 0.874) or total lower esophageal sphincter (3.7 [3.5–4.4] vs 3.6 [2.0–4.1] mm, P = 0.362). Patients with an outer longitudinal muscle ≥1.3 mm thick had a significantly lower mid‐term remission rate than others (36.3% vs 100%, P = 0.01). Conclusion Thickening of the outer longitudinal muscle at the lower esophageal sphincter is associated with poor mid‐term treatment outcomes for achalasia patients treated with pneumatic dilatation.