TABLE 3

The Modified Schwartz Criteria for Determining Probability of LQTS

1993–2011 LQTS Diagnostic Criteria
Points
Electrocardiographic findings
 QTc
   ≥480 ms3
  460–479 ms2
  450–459 ms (males)1
 QTc fourth minute of recovery from exercise stress test1
   ≥480 ms
  Tdp2
 T wave alternans1
 Notched T wave in 3 leads1
 Low heart rate for age0.5
Clinical history
 Syncope
  With stress2
  Without stress1
 Congenital deafness0.5
Family history
 Family members with definite LQTS1
 Unexplained sudden cardiac death below age 30 among intermediate family members0.5
  • In 2011, QTc at fourth minute of recovery from exercise stress was added (ref 26). QTc was calculated by Bazett’s formula, in which QTc = QT√RR. Score of 1 or less equals less probability of LQTS. 1.5 to 3 points equals intermediate probability of LQTS. 3.5 points equals high probability.