UBC Theses and Dissertations
Heart rhythm changes in eating disorders Janzen, Mikyla
Anorexia nervosa (AN) is a complex psychiatric disorder with the highest mortality rate of any eating disorder. A subset of these deaths may be sudden and attributed to cardiac rhythm changes which may be present during acute AN. Specifically, the repolarization phase of each heartbeat, as visualized by the QT interval on electrocardiogram (ECG), has been suggested as a potential prognostic tool. In addition, many AN patients are prescribed psychopharmacotherapy to treat concurrent depression and/or anxiety which may accentuate ECG changes. Through four research studies, this thesis explored three hypotheses: 1. Comprehensive cardiac testing is an effective and cost-efficient means of evaluation. 2. Psychopharmacotherapy will alter the ECG in eating disorders 3. Cardiac repolarization in AN will differ from healthy controls at rest and during exercise. In the first study, Hypothesis 1 was tested by means of a cost analysis of patients referred for inherited heart rhythm disorder evaluation. Analyses revealed multidisciplinary cardiac testing was effective and did not incur unreasonably high costs. Secondly, a retrospective case-control ECG review was conducted to evaluate Hypotheses 2 and 3. The QT interval was not clinically different between eating disorder patients and healthy controls, but patients were more likely to show T-wave flattening or inversion on ECG, which have been previously associated with SUD risk. Thirdly, Hypothesis 3 was further analyzed through a systematic review and meta-analysis of the current literature surrounding the resting QT interval in AN. Again, there was no difference in the QT interval, but AN patients had greater QT dispersion (interlead difference on ECG) compared to controls. QT dispersion has also been linked to increased SUD risk. Finally, we are prospectively assessing the ECG during modified exercise in eating disorder patients to further explore Hypothesis 3. Preliminary data suggest QT dynamics as heartrate increases may be abnormal. Overall, it appears that the resting QT interval may not be a direct marker of SUD risk in AN. However, more subtle markers of repolarization abnormality such as T-wave changes and QT dispersion may be superior at rest. During exercise, QT interval dynamics may regain relevance in assessing SUD risk.
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