Schwartz score diagnostic criteria for long QT syndrome (LQTS)
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 pointesΔ
2
T wave alternans
1
Notched T wave in 3 leads
1
Low heart rate for age◊
0.5
Clinical history
SyncopeΔ
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.