In addition to 'Electrocardiogram T wave amplitude decreased', there may be other similar symptoms or signs that better match your side effect. These have also been listed below for your convenience.

Long QT 2: The ECG shows low amplitude T waves frequently with a notch. Arrhythmias are more likely to occur during rest/sleep especially with sudden awakening and/or auditory stimuli.

U wave that occurs just after the T wave and is usually of smaller amplitude than the T wave. Flattening of the T wave. ST depression on occasion, which can mimic ischemia.