T-wave inversion was the most frequent ECG abnormality (n 31 patients), followed by ST segment changes (nine patients with elevation and six with depression). [ncbi.nlm.nih.gov]

Myocardial fibrosis is the most common cause. Associations: Inferior acute myocardial infarction. Sick sinus syndrome. Mobitz type II. Second-degree block plus new bundle branch or fascicular block. [patient.info]