Abstract P189: Cardiac Repolarization and Resting Energy Expenditure in Patients Hospitalized With Severe Anorexia Nervosa

Abstract

Background and Objectives: Anorexia nervosa (AN) carries the highest mortality among psychiatric illnesses and disproportionately impacts women. QTc prolongation is believed to underlie this risk but is a subject of controversy as ECG data among patients with advanced AN is inadequately characterized. Moreover, previous studies have utilized non-digitized ECG data and therefore have limited measurement precision. We sought to determine the prevalence of QTc prolongation and assess its relationship to body mass index (BMI) and resting energy expenditure (REE) within a national AN referral center. Methods and analysis: We identified 34 patients hospitalized with severe AN. ECGs were obtained on admission then digitized and read with high-precision calipers by a single blinded electrophysiologist. We evaluated the proportion of patients with marked QTc prolongation defined as exceeding 0.500 seconds. Descriptive statistics were used to summarize continuous normally distributed data. Categorical variables were summarized with frequencies and percentages. Pearson's and Spearman's correlation coefficients were used to determine if there was an association between QTc and admission BMI and REE calculated using the Harris Benedict equation. Findings: A total of 31 of 34 (91.2%) patients were women, and median age was 27 years. The median weight on admission was 81.4 pounds and median BMI was 13.5 kg/m 2 (interquartile range 11.8 - 14.5) Mean heart rate was 58 bpm and mean QTc calculated by the Fridericia formula was 0.421 seconds. A QTc interval exceeding 0.500 seconds was seen in only one patient (4.8%). There was no significant correlation between QTcF and either BMI (-0.20, p=0.39) REE (+0.19, p=0.40) on hospital admission. Conclusions: QTc interval prolongation occurs infrequently among patients with severe anorexia nervosa; most exhibit normal cardiac repolarization even at the height of their illness. Disease severity as assessed by admission BMI and REE is not significantly correlated with the QTc interval. Beyond the need for larger studies, these findings suggest that other markers of sudden death should be investigated within this vulnerable population.