There is controversy about ECG changes in MG. These changes are mostly non specific but the fact that they will regress after treatment of MG will rise this suspicion that MG causes these abnormalities. These abnormalities include  arrhythmias (which can increase the risk of sudden cardiac death, Q-T prolongation, conduction disturbances and ST-T changes.
Myasthenia gravis electrocardiogram
Guillain-Barré syndrome electrocardiogram
Multiple sclerosis electrocardiogram
Bartter syndrome electrocardiogram
Sarcoidosis electrocardiogram
Brugada syndrome electrophysiologic studies
Cardiomyopathy electrocardiogram
Scleroderma electrocardiogram