Table 1

LQTS Clinical Probability Score (Schwartz Score)

    Clinical history of syncope*
        Without stress1
        With stress2
    Congenital deafness0.5
    Family history of long QT syndrome†1
    Unexplained sudden death in a 1st degree family member <age 30†0.5
    Corrected QT interval (QTc by Bazett’s formula)
        450 ms (in males)1
        460–470 ms2
        ⩾480 ms3
    Torsade de pointes*2
    T-wave alternans1
    ⩾3 leads with notched T waves1
    Bradycardia (<2nd centile for age)0.5
  • Adapted from Schwartz et al14 with permission from the American Heart Association, copyright 1993.

  • ⩽1 = low probability; 1< score <4 = intermediate probability; ⩾4 = high probability.

  • *Syncope and torsade de pointes are mutually exclusive.

  • †Cannot count the same family member for both criteria.