Schwartz score diagnostic criteria for long QT syndrome (LQTS)

	Points
Electrocardiographic findings*
QTc^¶
≥480 ms	3
460 to 479 ms	2
450 to 459 ms (in males)	1
QTc^¶ fourth minute of recovery from exercise stress test ≥480 ms	1
Torsades de pointes^Δ	2
T wave alternans	1
Notched T wave in 3 leads	1
Low heart rate for age^◊	0.5
Clinical history
Syncope^Δ
With stress	2
Without stress	1
Congenital deafness	0.5
Family history
Family members with definite LQTS^§	1
Unexplained sudden cardiac death below age 30 among immediate family members^§	0.5

SCORE:

≤1 point = low probability of long QT syndrome (LQTS).
1.5 to 3 points = intermediate probability of LQTS.
≥3.5 points = high probability of LQTS.

* In the absence of medications or disorders known to affect these electrocardiographic features.
¶ QTc calculated by Bazett's formula where QTc = QT/√RR.
Δ Mutually exclusive.
◊ Resting heart rate below the second percentile for age.
§ The same family member cannot be counted in A and B.

From: Schwartz PJ, Crotti L. QTc behavior during exercise and genetic testing for the long-QT syndrome. Circulation 2011; 124:2181. DOI: 10.1161/CIRCULATIONAHA.111.062182. Copyright © 2011 American Heart Association. Reproduced with permission from Lippincott Williams & Wilkins. Unauthorized reproduction of this material is prohibited.

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Schwartz score diagnostic criteria for long QT syndrome (LQTS)