Table 2

Baseline characteristics of children and electrocardiographic data availability and quality

Female sex, n (%)23 (35.9)
Age at baseline (years), mean±SD12±3
Control, n (%)20 (31.3)
HCM, n (%)22 (34.4)
 MLVWT (mm), mean±SD15 mm±5 mm
 Maximum LVOT gradient (mm Hg), median (IQR)6 mm Hg (4 mm Hg)
 Medications, n6*
LQTS, n (%)22 (34.4)
 Resting QTc, mean±SD474 ms±45 ms
Baseline 12-lead ECG available, n (%)64 (100)
Missing baseline KM6LECG, n (%)5 (7.8)
Suspected lead misplacement baseline KM6LECG, n (%)‡1 (1.7)
Suspected lead misplacement unsupervised KM6LECG, n (%)§31 (18.5)
Suspected lead misplacement in all unsupervised KM6LECG4 (6.3)
Poor quality baseline supervised KM6LECG, n (%)‡4 (6.8)
Poor quality unsupervised KM6LECG, n (%)10 (6.0)
QTc calculated from other lead than II in baseline KM6LECG, n (%)‡6 (10.2)
  • *Four children on monotherapy beta-blocker, two children on two medications (disopyramide and beta-blocker in one, disopyramide and verapamil in one).

  • †All children on beta-blocker therapy (atenolol n=1, bisoprolol n=16, nadolol n=5).

  • ‡Denominator 59 children who had baseline KM6LECG available for review.

  • §Denominator 168 unsupervised KM6LECGs.

  • HCM, hypertrophic cardiomyopathy; KM6LECG, KardiaMobile 6-lead ECG; LQTS, long QT syndrome; LVOT, left ventricular outflow tract gradient; MLVWT, maximal left ventricular wall thickness.