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The Cardiac Danger Lurking in Anorexia

Discussion in 'Cardiology' started by Ghada Ali youssef, Mar 15, 2017.

  1. Ghada Ali youssef

    Ghada Ali youssef Golden Member

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    Anorexia nervosa is an important psychiatric disorder affecting mainly young females and this condition is associated with significant morbidity and mortality in this group. The high mortality rate is multifactorial and cardiac complications are common and can contribute about one third of the total deaths. Many of these cardiac deaths are sudden deaths mainly attributable to ventricular arrhythmias secondary to an acquired long- QT syndrome. It has been calculated that up to 25% of patients with anorexia nervosa have manifest QT prolongation. The severity of the malnutrition in a particular patient is an important determinant of QT prolongation.

    A problem that has been identified is that QT prolongation on a standard resting ECG in these patients may be mild and go unnoticed and undetected.

    The question is whether these patients can be fully assessed with a resting ECG (electrocardiogram) only. It is known that exercise testing can be used to demonstrate latent QT prolongation. Exercise testing can expose such a reduced reserve repolarization which is also a marker of increased risk of ventricular arrhythmias.

    A new study described changes in QT duration in response to graded exercise in patients with Anorexia Nervosa and compared them to an age-matched healthy control population.1

    Method
    Consecutive patients with anorexia nervosa were recruited from a hospital in Canada after their discharge from the hospital where they were treated for their Anorexia. In this way, 61 patients were recruited as were 45 healthy age-matched control normal people. The mean age was 15 years (range 12-19) in the control group and 15 years (range 10-19) in the patients with anorexia. Resting and graded exercise ECGs were done using a symptom-limited stress test on a cycle ergometer. The longest QT interval on the ECG was used for analysis. Changes of the QT interval during exercise were measured and QT/RR interval slopes were determined.

    Results
    The resting QT intervals were the same between the group with Anorexia and the group of healthy controls. During submaximal exertion at comparable heart rates, the QT interval prolonged significantly more in the Anorexia group than in the control healthy people. The QT/RR slopes were more gradual (more flat) in the anorexia patients than in the control healthy people.

    Conclusion
    At rest, the QT intervals of patients with anorexia were identical to healthy people age-matched. During exercise, there was significant prolongation of the QT interval in patients with Anorexia as compared to healthy matched normal people even in the absence of QT prolongation during rest. There was significantly impaired repolarisation reserve in patients with Anorexia as demonstrated during exercise. The important finding is that patients with anorexia may have significant QT prolongation during exercise which is absent during rest.

    Larger studies are needed to examine clinical outcomes and to evaluate whether exercise studies could be used to risk-stratify patients with anorexia.


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