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Changes to the electrocardiogram during exercise in anorexia nervosa.

Mikyla L Janzen¹, Christopher C Cheung¹, Nathaniel M Hawkins¹

¹Hearts in Rhythm Organization, Division of Cardiology, Department of Medicine, University of British Columbia, 220-1033 Davie St., Vancouver V6E 1M7, B.C., Canada.

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|June 20, 2020

Summary

Anorexia Nervosa patients show abnormal heart rhythm responses during exercise, with their QT interval failing to shorten unlike healthy individuals. This prolonged QT interval during exertion may explain the heightened risk of sudden cardiac death in Anorexia Nervosa.

Keywords:

Anorexia nervosa Exercise QT interval Repolarization

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Area of Science:

Cardiology
Psychiatry
Internal Medicine

Background:

Anorexia Nervosa (AN) is a severe eating disorder associated with significant mortality.
Electrocardiogram (ECG) abnormalities, particularly QT interval changes, are implicated in sudden cardiac death in AN patients.
The precise nature of QT interval dynamics during physiological stress, such as exercise, remains underexplored in AN.

Purpose of the Study:

To investigate and characterize QT interval behavior during a structured exercise test in individuals with Anorexia Nervosa.
To compare exercise-induced QT interval changes in AN patients with those of age- and sex-matched healthy controls.

Main Methods:

A prospective cohort study involving 18 Anorexia Nervosa patients and healthy controls.
A 6-minute modified exercise test protocol was administered.
A single-lead ECG patch recorded heart rate (HR) and QT interval, with QTc calculated for analysis.

Main Results:

Heart rate responses to exercise were comparable between AN patients and controls.
While healthy controls exhibited a shortening of the corrected QT (QTc) interval at maximum heart rate, AN patients demonstrated significant QTc prolongation.
Baseline and end-recovery QTc intervals were similar between the groups, but the dynamic change during exercise differed markedly.

Conclusions:

Anorexia Nervosa patients exhibit an impaired ability to shorten their QTc interval during exercise, unlike healthy individuals.
This blunted QTc response during exertion may be a key mechanism contributing to the increased risk of fatal arrhythmias and sudden cardiac death observed in AN.
Further research into cardiac electrophysiology in AN is warranted to understand and mitigate these risks.