Heart risk associated with weight loss in anorexia nervosa and eating disorders: risk factors for QT_c interval prolongation and dispersion

Abstract

Swenne I, Larsson PT. Heart risk associated with weight loss in anorexia nervosa and eating disorders: risk factors for QTc interval prolongation and dispersion. Acta Paediatr 1999; 88: 304-9. Stockholm. ISSN 0803-5253Risk factors for QT c interval prolongation and dispersion, indicators of an increased risk for cardiac arrhythmia and sudden death, have been investigated in patients with eating disorders (ED) and ongoing weight loss. Patients were characterized with regard to weight, body mass index (BMI; weight/length 2 ), duration of weight loss, rate of weight loss and rate of weight loss immediately preceding examination. At examination, a 12-lead electrocardiographic (ECG) registration and blood samples for analysis of serum electrolytes were obtained. In total, 92 examinations in 58 female patients aged 15.5 AE 1.7 (mean AE SD) y were analysed. Control ECG recordings were obtained from 38 normal-weight teenage girls with no known heart disease. Patients with ED weighed 40.7 AE 7.8 kg, corresponding to BMI 15.2 AE 2.4 kg/m 2 following a weight loss of 11.8 AE 6.5 kg. In ED patients, the ECG showed bradycardia, a shift to the right of the QRS axis, diminished amplitudes of the QRS complex and T wave, and prolongation and increased dispersion of the QT c interval. In multiple regression analyses low weight, low BMI and rapid weight loss immediately preceding the examination were the most important independent predictors of QT c interval prolongation and dispersion. It is concluded that an ECG examination is an important part of the assessment of patients with ED and ongoing weight loss, even in the absence of electrolyte disturbances, and especially if the patient is severely underweight or weight loss is rapid.

Incidence and Risk Factors of Prolonged QTc Interval in Type 1 Diabetes

“…This finding suggests that being extremely thin or overweight is not beneficial for women with type 1 diabetes. Accordingly, a cross-sectional study in Table 2 women with eating disorders has demonstrated that low BMI is an independent predictor of QTc interval prolongation, even in the absence of electrolyte disturbances (26). In our study, the effect of both glycemic and blood pressure control appeared also more evident in women, whereas age was the strongest predictor in men.…”

Characterization of Myocardial Repolarization Reserve in Adolescent Females With Anorexia Nervosa

“…It is therefore likely that QT/RR slope is a more sensitive measure of myocardial repolarization dynamics than simply measuring absolute QT interval or changes at peak exercise. Previous studies have found BMI to be a significant predictor of QTc duration; 9 however, this correlation is not a universal finding, 32 and other studies only detect a correlation with QT dispersion and LV mass index. 47 Certainly BMI is a guide to the severity of malnutrition, although it is imperfect, and because QT duration is affected by so many factors, the association between BMI and QT may not always be readily apparent, particularly in the context of moderate or minor reductions in BMI.…”

“…10 QT prolongation may occur in AN as a consequence of electrolyte abnormalities such as hypokalemia occurring as a direct consequence of malnutrition, 7,28 but QT prolongation can occur in the absence of overt biochemical disturbance. 6,8,9 Abnormal ion transport may also occur in malnourished cells independent of absolute serum electrolyte concentrations, 29 and such abnormalities may contribute to QT prolongation in AN. Consistent with our observation of decreased LV mass in the present cohort, a variety of structural changes may occur within the myocardium of patients with AN, including myocyte autolysis and hypotrophy and an increased concentration of cellular infiltrate and fibrotic tissue.…”

“…4 Many of these deaths are attributable to sudden cardiac death, 2,4 and a significant proportion of these may occur as a consequence of ventricular arrhythmias secondary to an acquired long-QT syndrome (LQTS). [5][6][7][8][9] The reported prevalence of QTc prolongation in AN is highly variable, with up to 25% of patients having manifest QT prolongation, 4,5 but QTc prolongation is more frequently mild and goes undetected with the use of standard reference ranges. 10 The severity of malnutrition is an important determinant of QTc prolongation 9 ; however, whether the risk of ventricular arrhythmia in AN can be fully assessed on the basis of the resting QTc interval is unknown.…”

“…[5][6][7][8][9] The reported prevalence of QTc prolongation in AN is highly variable, with up to 25% of patients having manifest QT prolongation, 4,5 but QTc prolongation is more frequently mild and goes undetected with the use of standard reference ranges. 10 The severity of malnutrition is an important determinant of QTc prolongation 9 ; however, whether the risk of ventricular arrhythmia in AN can be fully assessed on the basis of the resting QTc interval is unknown. A similarly wide variation in the QTc interval exists among patients with congenital LQTS, with up to 50% of disease-causing LQTS mutation carriers having a resting QTc interval in the normal or borderline range.…”