Transtelephonic electrocardiographic monitors for evaluation of children and adolescents with suspected arrhythmias

Objective. Patient-activated transtelephonic electrocardiographic event monitors (TTMs) are often used for the evaluation of children and adolescents with suspected arrhythmias. Since their introduction 25 years ago, there has been little inquiry quantifying the usefulness of TTMs for pediatric patients. The objective of this study was to measure the utility of TTMs for children and adolescents with symptoms of a possible cardiac rhythm disturbance. Methods. Medical records of all patients who received TTMs from C. S. Mott Children's Hospital Electrocardiography Laboratory between February 1, 1993, and October 31, 2000, were reviewed. Patients with pacemakers, known arrhythmias, or age older than 18 years were excluded. Indications for monitoring included palpitations with or without other symptoms ( N = 420), chest discomfort (N = 43), and presyncope or syncope (N = 32). Results. A total of 495 studies ( patient mean age: 10.2 +/- 4.3 years; range: 0.1 - 17.9 years; 48% male) met inclusion criteria. Monitoring was performed for 1 to 1021 consecutive days ( mean: 103 +/- 97). Fifty-two percent ( N = 257) of patients failed to transmit an electrocardiogram while experiencing symptoms. Fewer boys transmitted electrocardiograms ( N = 100/238). Of 238 symptomatic patients, 15% ( N = 35; mean age: 11.4 +/- 4.7 years; range: 0.1 - 17.4 years; 51% male) had supraventricular tachycardia (SVT). No other significant arrhythmia that may warrant treatment was identified. All patients with SVT had palpitations. No patients with isolated chest discomfort, presyncope, or syncope had SVT ( N = 75). SVT was documented more frequently in patients with postevent ( N = 35/464) than loop recorders ( N = 0/31). Of those with SVT, 71% ( N = 25) and 91% ( N = 33) transmitted events within 4 and 16 weeks, respectively. Followup for 1 to 108 months ( mean: 32 +/- 25; median: 26) in 53% ( 243 of 460) of patients without SVT uncovered a 3% ( N = 7) rate of subsequent SVT detection. The overall sensitivity of the TTM test was 83% ( 35 of 42) for detection of SVT. The sensitivity of studies theoretically limited to 4 and 16 weeks would be 60% ( 25 of 42) and 79% ( 33 of 42), respectively. The negative predictive value of the TTM study was 99% in our patient population. The negative predictive value of tests theoretically limited to 4 and 16 weeks would be 96% and 98%, respectively. TTM studies of 2 weeks' duration were most cost-effective in terms of total diagnostic yield. In contrast, studies of 4 weeks' duration were most cost-efficient for SVT detection. Conclusions. TTMs are useful for the evaluation of children and adolescents with palpitations but not with isolated chest pain, syncope, or presyncope. In this study, girls were more likely to transmit events. The sensitivity of TTMs for detection of SVT was 83%. The negative predictive value of the TTM test was 99%. Monitoring for longer than 16 weeks did not increase test sensitivity. Studies of 4 weeks' duration proved most cost-effective for SVT detection.