Exaggerated smooth muscle contraction segments on esophageal high-resolution manometry: prevalence and clinical relevance.

BACKGROUND: Two smooth muscle contraction segments (S2, S3) on esophageal high-resolution manometry (HRM) demonstrate varying contraction vigor in symptomatic patients. Significance of isolated exaggerated smooth muscle contraction remains unclear.
METHODS: High-resolution manometry studies were reviewed in 272 consecutive patients (56.4 ± 0.8 years, 62% F) and compared to 21 healthy controls (27.6 ± 0.6 years, 52% F), using HRM tools (distal contractile integral, DCI; distal latency, DL; integrated relaxation pressure, IRP), Chicago Classification (CC) and multiple rapid swallows (MRS). Segments were designated merged when the trough between S2 and S3 was ≥150 mmHg, and exaggerated S3 when peak S3 amplitude was ≥150 mmHg without merging with S2. Presenting symptoms and global symptom severity (on 100 mm visual analog scale) were recorded. Prevalence of merged and exaggerated segments was determined, and characteristics compared to symptomatic patients with normal HRM, and to healthy controls. KEY
RESULTS: Merged segments were identified in 5.6%, and exaggerated S3 in another 12.5%, but only 17-50% had a CC diagnosis; one healthy control had merged segments. DCI with wet swallows was similar in cohorts with merged and exaggerated segments (p = 0.7), significantly higher than symptomatic patients with normal HRM and healthy controls (p ≤ 0.003 for each comparison). Incomplete inhibition and prominent DCI augmentation on MRS (p ≤ 0.01), and presenting symptoms (chest pain and dysphagia, p = 0.04) characterized exaggerated segments, but not demographics or symptom burden. CONCLUSIONS & INFERENCES: Merged esophageal smooth muscle segments and exaggerated S3 may represent hypermotility phenomena from abnormal inhibition and/or excitation, and are not uniformly identified by the CC algorithm.