Table 1.

LQTS Clinical Probability Score (Schwartz Score)

Finding	Points
History
Clinical history of syncope*
Without stress	1
With stress	2
Congenital deafness	0.5
Family history of long QT syndrome†	1
Unexplained sudden death in a 1st degree family member <age 30†	0.5
ECG
Corrected QT interval (QTc by Bazett’ formula)
450 ms (in males)	1
460–470 ms	2
≥480 ms	3
Torsade de pointes*	2
T-wave alternans	1
≥3 leads with notched T waves	1
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.