How does anorexia nervosa affect the cardiovascular system?

Updated: Jun 10, 2019
  • Author: Bettina E Bernstein, DO; Chief Editor: Caroly Pataki, MD  more...
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Answer

Cardiac complications are the most common cause of death; the mortality rate is about 10%. Cardiac effects from anorexia nervosa include profound bradycardia, hypotension, decreased size of the cardiac silhouette, and decreased left ventricular mass associated with abnormal systolic function. Patients with anorexia report fatigue and have an attenuated blood pressure response to exercise and reduction in maximal work capacity. An increased incidence of mitral valve prolapse without significant mitral regurgitation is also observed. Low potassium-dependent QT prolongation increases the risk of ventricular arrhythmia. [20]

The patient's vital signs reflect hypotension with systolic pressures as low as 70 mm Hg and sinus bradycardia with heart rates as low as 30-40 beats per minute. These changes are a response to a decrease in the basal metabolic rate. The mechanism may be due to an autonomic imbalance in heart rate regulation, with increases in vagal activity and a reduction in sympathetic activity. These changes are physiologic cardiovascular responses, and treatment is unnecessary, unless negative clinical sequelae are present.

If electrocardiography (ECG) is performed, evidence of sinus bradycardia, ST-segment elevation, T-wave flattening, low voltage, and rightward QRS axis is apparent. All the aforementioned changes are clinically insignificant; however, the frequency of rhythm disturbances is most concerning, especially QT-interval prolongation that may be an indication for those at risk of cardiac arrhythmias and sudden death.

Cardiac decompensation is greatest during the initial 2 weeks of refeeding, when the myocardium cannot withstand the stress of an increased metabolic demand. However, if the daily weight gain is 0.2-0.4 kg, then complications are limited.


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