Chicago Classification Version 4.0 and Its Impact on Current Clinical Practice.

High-resolution manometry (HRM) has revolutionized esophageal motility testing, and the evolving Chicago Classification has been critical in codifying HRM metrics and definitions of old and new motility disorders. The latest Chicago Classification (version 4.0) is the result of a working group of 52 members (10 women) from 20 countries. Two critical new elements are the expansion of the normal database from 75 to 469 healthy volunteers and the recommendation of ancillary function tests (timed barium esophagram, functional lumen imaging planimetry, and/or impedance) to help with inconclusive HRM metrics, especially in cases of suspected achalasia, esophagogastric junction outflow obstruction (EGJOO), and ineffective esophageal motility (IEM). Important changes relevant to clinical practice include (1) refinement of the diagnosis criteria for EGJOO, which now require elevated integrated relaxation pressure in an upright position along with primary symptoms of dysphagia/noncardiac chest pain and obstruction at the esophago-gastric junction; (2) exclusion of mechanical obstruction in cases of suspected distal esophageal spasm and hypercontractile esophagus; and (3) a shift to a more restrictive metric (>70% ineffective peristalsis) for a diagnosis of IEM. In addition, the working group urged caution in using treatments such as pneumatic dilation or myotomy, which can irreversibly destroy lower esophageal sphincter competency and peristalsis, as the natural history of EGJOO/hypercontractile esophagus is poorly understood and spontaneous symptom resolution is common. Future versions should address the routine use of impedance with HRM, the role of HRM in pharyngeal/upper esophageal sphincter diseases, and the need for better criteria to determine which subsets of spastic disorders warrant aggressive treatment, as is done with achalasia.