Comparison of paediatric patients evaluated for postural orthostatic tachycardia syndrome with and without tachycardia.

ABSTRACT

INTRODUCTION: Postural orthostatic tachycardia syndrome is a debilitating disorder. We compared paediatric patients with this dysautonomia presenting with and without peak upright heart rate > 100 beats per minute. MATERIALS AND METHODS: Subjects were drawn from the Postural Orthostatic Tachycardia Syndrome Program database of the Children's Hospital of Philadelphia diagnosed between 2007 and 2018. Subjects were aged 12-18 years at diagnosis with demographic data, supine and peak heart rate from 10-minute stand, symptoms, and family history. Patients were divided into "low heart rate" (peak less than 100 beats/minute) and "high heart rate" (peak at least 100 beats/minute) groups. RESULTS: In total, 729 subjects were included (low heart rate group 131 patients, high heart rate group 598 patients). The low heart rate group had later age at diagnosis (16.1 versus 15.7, p = 0.0027). Median heart rate increase was 32 beats/minute in the low heart rate group versus 40 beats/minute in the high heart rate group (p < 0.00001). Excluding palpitations and tachypalpitations, there were no differences in symptom type or frequency between groups. DISCUSSION: Paediatric patients meeting heart rate criteria for postural orthostatic tachycardia syndrome but without peak heart rate > 100 demonstrate no difference in symptom type or frequency versus those who meet both criteria. Differences observed reached statistical significance due to population size but are not clinically meaningful. This suggests that increased heart rate, but not necessarily tachycardia, is seen in these patients, supporting previous findings suggesting maximal heart rate is not a major determinant of symptom prevalence in paediatric postural orthostatic tachycardia syndrome.