A wearable remote monitoring system for the identification of subjects with a prolonged QT interval or at risk for drug-induced long QT syndrome.

BACKGROUND: A correct measurement of the QT interval in the out-of-hospital setting is important whenever the long QT syndrome (LQTS) is suspected or a therapy might lead to drug-induced LQTS (diLQTS) because QT interval monitoring in the initial days of therapy could alert to dangerous QT prolongation. We explored whether automated QTc measurements (BGM) by BodyGuardian™ (BG), a wearable remote monitoring system, are sufficiently reliable compared to our own manual measurements (MM) performed on the same beats during 12‑lead Holter recordings in LQTS patients (pts) and in healthy controls.
METHODS: We performed 351 measurements in 20 LQTS pts and 16 controls. MM and BGM were compared by a Bland-Altman plot (BAp). High values of BAp indicate large differences between measurements.
RESULTS: In all 36 subjects QTc was 446 ± 41 and 445 ± 47 ms in MM and BGM, respectively. The mean ± SE BAp was -1.4 ± 1.8 ms for QTc in all subjects, 8.3 ± 2.3 and -7.2 ± 2.5 ms respectively in controls and LQTS. The disagreement between BGM and MM <15 ms in all, in controls, and in LQTS was respectively 57%, 63% and 54%. Among controls, there were only 3/132 false positive measurements (BGM QTc >470 ms when MM QTc <440 ms) in 3 different subjects. Among LQTS, there were 10/219 false negative measurements (BGM QTc <440 ms when MM QTc >470 ms) in 6 pts, but only two had multiple false negative values.
CONCLUSIONS: This wearable monitoring system reliably identifies a prolonged QT interval and probably also subjects at risk for diLQTS.