Table 3

Findings on the KardiaMobile 6-lead KM6LECG compared with the baseline 12-lead ECG in children with HCM and LQTS

ParameterNBaseline 12-lead ECGBaseline KM6LECGKM6LECG
Sensitivity (%)Specificity (%)Positive predictive valueNegative predictive value
HCM
 Any atrial enlargement2073431001.00.76
 Pathological Q-waves20331001001.01.0
 Mean QRS >120 ms20221001001.01.0
 QRS axis abnormal2091189730.730.89
 Prolonged QTc196576920.810.90
 Any repolarisation abnormality*19131392830.920.83
 HCM-suggestive features shown†191810561001.00.11
  Features evident in limb leads only19101090890.900.89
LQTS
 Prolonged QTc‡19111191880.910.88
 Abnormal T-wave morphology§2010970800.780.73
 Either prolonged QTc and/or abnormal T-wave morphology20151487800.920.67
  • *Any repolarisation abnormality: including any of abnormal T-wave morphology in limb leads, ST depression or elevation, abnormal T-wave inversion or QTc prolongation (>450 ms for males, >460 ms for females). One child (HCM) was excluded due to incalculable QTc on baseline 12-lead ECG.

  • †HCM-suggestive features shown: including any of abnormal T-wave inversion, pathological Q-waves, left or extreme QRS axis deviation or voltage criteria LVH (voltage criteria LVH 12-lead ECG only), one child excluded as unable to assess repolarisation in the setting of bundle branch block.

  • ‡Prolonged QTc defined as >450 ms for males or >460 ms for females.

  • §Abnormal T-wave in both limb leads and precordial leads, only limb leads assessed on KM6LECG.

  • HCM, hypertrophic cardiomyopathy; KM6LECG, KardiaMobile 6-lead ECG; LQTS, long QT syndrome; LVH, left ventricular hypertrophy; QTc, corrected QT interval.