Table 2.
1993–2011 LQTS DIAGNOSTIC CRITERIA
| POINTS | |||
|---|---|---|---|
| ELECTROCARDIOGRAPHIC FINDINGS | |||
| A | QTc^ | ≥ 480 ms | 3 |
| 460 – 479 ms | 2 | ||
| 450 – 459 (male) ms | 1 | ||
| B | QTc^ 4th 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 AGE 30 AMONG IMMEDIATE FAMILY MEMBERS $ | 0.5 | |
# In the absence of medications or disorders known to affect these electrocardiographic features
^
QTc calculated by Bazett's formula where QTc = QT/√RR
*
Mutually exclusive
@
Resting heart rate below the 2nd 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
≥ 5 points high probability
(From ref. 36)