TABLE 4.
T wave morphology characteristics for common causes of congenital and acquired long QT syndrome.
| Typical T wave morphology characteristics | |
|---|---|
| Congenital LQTS | |
| Long QT type 1 (KCNQ1) | Broad based |
| Long QT type 2 (KCNH2) |
Bifid (notched), low voltage T wave alternans (biphasic) |
| Long QT type 3 (SCN5A) | Late onset (prolonged ST segment), high amplitude and narrow T wave |
| Calmodulin (CALM1,2,3) | T wave alternans |
| Triadin (TRDN) | Extensive T wave inversion (precordial leads) |
| Anderson‐Tawil syndrome (KCNJ2) |
Broad based (prolonged T wave downslope) Bifid (wide T‐U junction) |
| Timothy syndrome (CACNA1c) |
Late onset, small T waves Giant negative T waves (inversion) T wave alternans |
| Ankyrin‐B syndrome (ANK2) |
Broad based T wave inversion Bifid |
| Acquired LQTS | |
| Hypocalcemia | T wave flattening, broad based |
| Hypokalemia |
Bifid (U wave may be present) T wave flattening T wave inversion |
| Hypomagnesemia | T wave flattening, broad based |
| Hypothermia |
Broad based Biphasic (T wave alternans) |
| Hypothyroidism | T wave inversion |
| Pheochromocytoma | Giant negative T waves (inversion) |
| Quinidine |
T wave flattening Bifid, broad (U wave may be present) |
| Stroke | Deep T wave inversion |
| Takotsubo's cardiomyopathy | T wave inversion |