Katrin Schwameis, MD, Stephanie Worrell, MD, Steven R DeMeester, MD. Keck Hospital, USC
Background: High-resolution manometry (HRM) identifies three subtypes of achalasia. Type II, with pan-esophageal pressurization (PEP), and Type III with distal spastic contractions appear very different on HRM to the flaccid body and lack of PEP in patients with Type I achalasia. Per-oral endoscopic myotomy (POEM) relieves the outflow obstruction at the lower esophageal sphincter (LES) without adding new resistance from the addition of a partial fundoplication. The aim of this study was to evaluate HRM changes in patients with achalasia Types II and III after POEM.
Methods: We reviewed the records of all patients with achalasia Types II and III that underwent POEM and had both pre and post-operative HRM, upper endoscopy and timed barium swallow (TBS).
Results: There were 31 patients that had POEM for achalasia Types II or III and 16 patients, 12 Type II and 5 Type III, had pre and post-POEM studies at a median of 4.9 months. All patients with Type II and 2/5 patients with Type III achalasia showed PEP pre-POEM. Post-POEM, PEP resolved in 72.7 % of type II patients (Figure) but in none with Type III (Table). The mean IRP and LES resting pressure were significantly reduced after POEM, and was similar for Type II and III achalasia (p=0.33 and 0.75 respectively). However, post-POEM IRP was lower in those with resolution of PEP compared to those with persistent PEP (9.5 vs. 16.7, p= 0.025). There was no difference in the LES resting pressure post-POEM in those with and without resolution of PEP (14.9 mmHg vs 20.7 mmHg, p= 0.18). Compared to those with residual PEP, those with resolution of PEP had similar dysphagia relief (80% vs 75%, p=0.84), esophageal emptying on TBS (97% at 5 min vs 89% at 5 min, p=0.16) and frequency of post-POEM esophagitis (60% vs 62.5%, p=0.93). No patient with Type II achalasia had return of peristalsis post-POEM compared to 2/5 (40%) with Type III achalasia. No Type III patient on post-POEM HRM looked like Type I or II.
Conclusions: POEM leads to significant relief of LES outflow resistance and resolution of PEP in most patients with Type II achalasia. Persistent PEP was associated with a higher post-POEM IRP but not resting pressure, and similar symptom relief, improvement in TBS esophageal emptying and frequency of esophagitis compared to those with resolution of PEP in the short term. Long-term implications of persistent PEP will be important to ascertain.