In achalasia, manometric subtype II patients have the greatest treatment success rates, compared with type I and type III patients.
Moreover, the finding applies both to patients treated with pneumatic dilation and to those treated with laparoscopic Heller myotomy, which have comparable high success rates in this population, reported Dr. Wout O. Rohof and Dr. Renato Salvador in the April issue of Gastroenterology (doi: 10.1053/j.gastro.2012.12.027).
Lead coauthors Dr. Rohof and Dr. Salvador, from the Academic Medical Center in Amsterdam and the Padova (Italy) University Hospital, respectively, and their colleagues looked at data from nearly 200 patients who participated in the previously published European Achalasia Trial (N. Engl. J. Med. 2011;364:1807-16).
In that study, 201 patients were randomly assigned to undergo either pneumatic dilation or Heller myotomy, with the result being that both treatments produced equally high success rates in achalasia patients.
In the current study, the investigators looked at the 176 patients for whom pretreatment conventional myometric grading was available, to see whether treatment response rates were higher in subtype I, II, or III.
Briefly, according to Pandolfino et al., subtype I refers to patients in whom the esophageal body exhibits minimal contractility; type II to patients who lack peristalsis but demonstrate intermittent periods of compartmentalized esophageal pressurization; and type III to patients who exhibit spastic contractions in the distal esophagus (Gastroenterology 2008;135:1526-33).
Overall, 44 patients (25%) had achalasia type I, 114 (65%) had type II, and 18 (10%) type III.
In the European Achalasia Trial, there were no statistically significant differences in age or sex between patient subtypes, and subtypes were equally distributed over the two treatment protocols, wrote the authors.
The researchers found that among type I patients, there was no significant difference in success rates between dilation and myotomy (81% vs. 85%, respectively; P less than .01), with success defined as a drop in Eckardt score to 3 or less at 1 year post treatment.
"In contrast, in type II, the success rate for dilation was significantly higher than that of myotomy, ... with 100% treatment success in the [dilation] group, compared to 93% in the [myotomy] group," the authors wrote (P less than .05).
Type III patients, in contrast, had overall lower success rates, with 86% for myotomy and 40% for dilation (the difference between the groups could not be assessed for significance because there were too few patients with type III achalasia).
In any case, "irrespective of treatment arm, success rate after a mean follow-up of 43 months was significantly higher in patients with type II compared to type I (P less than .01) and type III (P less than .001)," the researchers wrote.
The authors conceded that the manometry subtype classification system developed by Pandolfino was designed for use with high-resolution manometry instead of the conventional manometry used in their study.
They noted, however, that at least one study has found 100% agreement between the classification of subtypes based on conventional pressure line tracings versus high-resolution manometry plots, and "our three patient groups were similar to those reported by Pandolfino, in terms of both clinical features and outcome after therapy."
Indeed, "based on our findings, we conclude that when a graded distension protocol allowing redilation is used, pneumatic dilation and laparoscopic Heller myotomy are both appropriate treatment options for type I and type II achalasia, at least until longer follow-up data are available," the authors concluded.
The researchers stated that they had no competing interests to disclose in relation to this study. One of the authors disclosed being funded by a grant from the Flemish government.