QTc prolongation not inherent in eating disorders

The population-mean heart-rate–corrected QT interval (QTc) in a cohort of patients with eating disorders is normal and varies by subtype, according to a study. Marked QTc prolongation only occurs in the presence of external factors, indicating that QTc prolongation is not intrinsic to eating disorders.

“Anorexia nervosa is associated with a markedly increased risk of sudden cardiac death, but the mechanism has not been elucidated,” they said. “Whether QT prolongation is an intrinsic feature of eating disorders is uncertain because previous studies are limited by small sample size, and extrinsic factors associated with QT prolongation were inconsistently reported.”

In this study, electrocardiogram data were assessed from 1,026 consecutive adults admitted into residential treatment based on subtype: anorexia nervosa (caloric restriction only), anorexia nervosa binge-purge, and bulimia nervosa. Eating disorder not specified were excluded.

The authors performed population-mean Fridericia-corrected QTc and categorized QTc threshold analysis. Multivariable regression was performed, controlling for age, sex, duration of illness, body mass index, hypokalaemia, QTc-prolonging drugs, purging behaviours, and laxatives.

A total of 906 patients were included, among whom the population-mean QTc (424±25) was found to be normal and lowest in the anorexia nervosa subgroup (417.3±22.3; p<0.001 vs other subgroups). Only 11 (1.2 percent) patients had substantial QTc prolongation (QTc >500 ms); all of them had hypokalaemia and received QTc-prolonging medications or laxatives.

Differences in mean QTc across eating disorder subtypes diminished but persisted after controlling for clinically relevant covariates (p=0.048).

Further research is warranted to define the aetiology of sudden death in patients with eating disorders, according to the authors.