Electrocardiographic abnormalities associated with malignant hyperthermia susceptibility.

Serial ECG's were reviewed in 93 consecutive patients who were proven to be susceptible to malignant hyperthermia by caffeine contracture and ATP depletion tests on skeletal muscle biopsies, but who were without a history of pyrexic crises. There were 46 males and 47 females with a mean age of 33 years. Abnormal ECG's were found in 26 of the patients, with conduction defects in 14, repolarization abnormalities (non-specific ST-T changes) or "Q" waves in nine and increased voltages suggesting left ventricular hypertrophy in three (in the absence of hypertension). An abnormal ECG in a young patient may reflect malignant hyperthermia susceptibility.