. Author manuscript; available in PMC: 2014 Jul 16.

Published in final edited form as: J Am Coll Cardiol. 2013 May 15;62(3):169–180. doi: 10.1016/j.jacc.2013.04.044

Table 1. 1993-2012 LQTS Diagnostic Criteria.

			Points
ELECTROCARDIOGRAPHIC FINDINGS^#
		≥480 ms	3
A	QTc^ˆ	460 – 479 ms	2
		450 – 459 (male) ms	1
B	QTc^ˆ 4^th minute of recovery from exercise stress test ≥ 480 ms		1
C	TORSADE DE POINTES ^*		2
D	T WAVE ALTERNANS		1
E	NOTCHED T WAVE IN 3 LEADS		1
F	LOW HEART RATE FOR AGE ^@		0.5
CLINICAL HISTORY
A	SYNCOPE ^*	WITH STRESS	2
		WITHOUT STRESS	1
B	CONGENITAL DEAFNESS		0.5
FAMILY HISTORY
A	FAMILY MEMBERS WITH DEFINITE LQTS ^$		1
B	UNEXPLAINED SUDDEN CARDIAC DEATH BELOW		0.5
	AGE 30 AMONG IMMEDIATE FAMILY MEMBERS ^$

In the absence of medications or disorders known to affect these electrocardiographic features

^ˆ

QTc calculated by Bazett's formula where QTc = QT/√RR

Mutually exclusive

Resting heart rate below the 2^nd percentile for age

The same family member cannot be counted in A and B

Score: ≤ 1 point: low probability of LQTS

1.5 to 3 points: intermediate probability of LQTS

≥ 3.5 points high probability

(From ref. 6)