QTc Prolongation and Risk of Torsades de Pointes in Hospitalized Pediatric Oncology Patients.

Objective: To evaluate the prevalence of torsades de pointes and to identify risk factors associated with QTc prolongation of ≥500 milliseconds in hospitalized pediatric oncology patients. A QTc prolongation of ≥500 milliseconds is associated with higher mortality in hospitalized adults but has not been demonstrated in pediatrics. Study

Design: A single-center, retrospective review of all hospitalized oncology patients ≤21 years of age was performed from 2014 to 2016. Patients with long/short QT syndrome or a QRS interval of ≥120 ms were excluded. Rapid response events were reviewed to determine the prevalence of torsades. In patients with ECGs for review, data were compared between patients with a QTc of <500 and ≥500 ms via logistic regression.

Results: There were 1934 hospitalized patients included. Rapid response events occurred in 90 patients (4.7%) with 2 torsades events (0.1%). There were 1412 electrocardiograms performed in 287 unique patients (10.6 ± 6.3 years of age; 43% female). The mean QTc was 448 ± 31 ms; 25 patients (8.7%) had ≥1 ECG with a QTc of ≥500 ms. The prevalence of torsades was greater in patients with a QTc of ≥500 ms (8% vs 0%; P<.01). In multivariate analysis, factors associated with a QTc of ≥500 ms included female sex, (OR 2.95) and ≥2 QT-prolonging medications (OR, 2.95).

Conclusions: The prevalence of torsades in hospitalized pediatric oncology patients was low (0.1%), although the risk was significantly greater in patients with a QTc of ≥500 ms. Routine monitoring of electrocardiograms and electrolytes is essential in patients with risk factors predisposing to QTc prolongation.