Characterization of Myocardial Repolarization Reserve in Adolescent Females With Anorexia Nervosa

Abstract

Background-Patients with anorexia nervosa exhibit abnormal myocardial repolarization and are susceptible to sudden cardiac death. Exercise testing is useful in unmasking QT prolongation in disorders associated with abnormal repolarization. We characterized QT adaptation during exercise in anorexia. Methods and Results-Sixty-one adolescent female patients with anorexia nervosa and 45 age-and sex-matched healthy volunteers performed symptom-limited cycle ergometry during 12-lead ECG monitoring. Changes in the QT interval during exercise were measured, and QT/RR-interval slopes were determined by using mixed-effects regression modeling. Patients had significantly lower body mass index than controls; however, resting heart rates and QT/QTc intervals were similar at baseline. Patients had shorter exercise times (13.7±4.5 versus 20.6±4.5 minutes; P<0.001) and lower peak heart rates (159±20 versus 184±9 beats/min; P<0.001). The mean QTc intervals were longer at peak exercise in patients (442±29 versus 422±19 ms; P<0.001). During submaximal exertion at comparable heart rates (114±6 versus 115±11 beats/min; P=0.54), the QTc interval had prolonged significantly more in patients than controls (37±28 versus 24±25 ms; P<0.016). The RR/QT slope, best described by a curvilinear relationship, was more gradual in patients than in controls (13.4; 95% confidence interval,12.8-13.9 versus 15.8; 95% confidence interval, 15.3-16.4 ms QT change per 10% change in RR interval; P<0.001) and steepest in patients within the highest body mass index tertile versus the lowest (13.9; 95% confidence interval, 12.9-14.9 versus 12.3; 95% confidence interval, 11.3-13.3; P=0.026). Conclusions-Despite

Characterization and correlates of exercise among adolescents with anorexia nervosa and bulimia nervosa

“…The QTc is the measure of the time between the start of the Q wave and the end of the T wave on the patient's electrocardiogram, corrected for heart rate, which represents the electrical depolarization and repolarization of the ventricles of the heart (Postema & Wilde, ). A lengthened QTc interval may be associated with increased risk for a ventricular arrhythmia and sudden death (Padfield et al, ; Postema & Wilde, ). Previous studies in non‐ED populations demonstrated lengthening (Meher, Bhattacharjee, Rampal, Kapoor, & Sharma, ), shortening (Chinushi et al, ; Srinath & Ravipati, ), or mixed results (Berger et al, ) of the QTc postexercise.…”

Response by Padfield and Krahn to Letter Regarding Article, “Characterization of Myocardial Repolarization Reserve in Adolescent Females With Anorexia Nervosa”

“…We thank Aparci et al for their interest in our article 1 and for the interesting points they raise. We agree that the pathogenesis of ventricular arrhythmias in anorexia nervosa (AN) is likely to be multifactorial; however, the argument that excess growth hormone (GH) may be responsible for arrhythmogenesis in AN is not particularly convincing.…”

An Endomyocardial Biopsy of the Left Ventricle in an Anorexia Nervosa Patient with Sinus Bradycardia and Left Ventricular Systolic Dysfunction

“…The main cardiovascular complications in patients with AN are bradycardia, systolic dysfunction, impaired ventricular repolarization, low blood pressure, QT interval prolongation, mitral valve prolapse, and reduction of myocardial contractility [1, 2]. The mechanistic pathways linking AN to left ventricular systolic function decline are not clear.…”