METHODS: A multicentre, ambi-directional, non-randomized comparison of intra-procedural complications during the learning curve of POEM was performed against a historical cohort of LHM + F. Demographic, clinicopathological, procedural data and complications were collected. A direct head-to-head comparison was performed, followed by a population pyramid of complication frequency. Case sequence was then divided into blocks of 5, and the complication rates during each block was compared to the historical cohort.

RESULTS: From January 2010 to April 2021, 60 patients underwent LHM + F and 63 underwent POEM. Mean age was lower for the POEM group (41.7 years vs 48.1 years, p = 0.03), but there was no difference in gender nor type of Achalasia. The POEM group recorded a shorter overall procedural time (125.9 min vs 144.1 min, p = 0.023) and longer myotomies (10.1 cm vs 6.2 cm, p = 0.023). The overall complication rate of POEM was 20.6%, whereas the historical cohort of LHM + F had a rate of 10.0%. On visual inspection of the population pyramid, complications were more frequent in the earlier procedures. On block sequencing, complication frequency could be seen tapering off dramatically after the 25th case, and subsequently equalled that of LHM + F.