Reprinted from Eating Disorders Review
November/December 2001 Volume 12, Number 6
©2001 Gürze Books
Cardiac abnormalities are common among patients with anorexia nervosa. Findings from two recent studies provide new information about cardiovascular changes in such patients.
Exercise: Why do patients have low cardiac workloads?
Despite cardiac abnormalities, many patients can successfully exercise at a high level. Findings from a controlled study at the University of Pisa, Italy, help explain why.
To test exercise performance in patients with anorexia nervosa, the researchers compared 19 female patients with anorexia nervosa (mean age: 23 years) and 20 constitutionally thin women matched for age, height and level of physical activity. For the women with anorexia nervosa, mean weight was 37.3 kg and body mass index (BMI) was 14.4 kg/m2. The thin women had a mean BMI <19 kg/m2. All the women underwent clinical examination, standard ECG tests, and a cardiopulmonary stress test (Ital Heart J 2:462).
Patients with anorexia nervosa had a lower heart rate and lower systolic blood pressure at peak exercise (148.8 vs. 171 beats per minute) and a significantly lower workload (85.5 vs. 117.2 W), and oxygen uptake (VO2), both at rest and at maximum VO2 (9.5 vs. 12.8, and 28.0 vs. 40.2 ml/kg/minute) than the women without anorexia nervosa. Cardiac workload, rate pressure product, anaerobic threshold, maximum minute ventilation, and oxygen pulse were all significantly lower among the women with anorexia nervosa than the control group.
The authors hypothesize that the low VO2, both at rest and during exercise, allows patients with anorexia nervosa to maintain a relatively high level of physical activity.
Abnormal ECG findings
Patients with anorexia nervosa also have abnormal findings on electrocardiography, including prolonged QT duration and dispersion. After their experience with 49 patients, Belgian clinicians advise that marked repolarization changes (such as prolonged QT interval and/or T wave shapes) in patients with anorexia nervosa should not be taken as a normal feature of the disease, but should call for a search for other potential causes, such as metabolic and electrolyte disturbances or drug reactions (J Cardiol 2000;34:42).