Table 1.

Schwartz score.

ECG features *

A   QTc interval #, ms     ≥480            3       460–479          2       450–459 (males)     1

B   QTc interval # ≥ 480 ms at 4 min recovery from the exercise stress test 1

C   Torsade de pointes §    2

D   T-wave alternans     1

E   Notched T-wave in three leads  1

F   Low heart rate for age δ  0.5

Clinical history

A   Syncope §                With stress                  2                Without stress                  1

B   Congenital deafness                         0.5

Family history &

A    Family member with definite LQTS                 1

B    Unexplained sudden cardiac death age <30 years among immediate family members 0.5

Score ≤ 1: low probability; 1.5 to 3, intermediate probability; ≥3.5, high probability. * In the absence of medications or disorders known to prolong QTc. ^# QTc interval calculated by the Bazett formula. ^§ Mutually exclusive. ^δ Resting HR < second percentile for age. ^& The same family member cannot be used for both A and B. LQTS: long QT syndrome.