Electrocardiography:

With every heartbeat, a weak current is generated which is recorded using electrocardiography (ECG) and provides information about the electrical activity of the heart.

What can you assess with an ECG?

Heart rhythm and heart rate
Atrial fibrillation
myocardial infarction
Circulatory disorders of the heart muscle
Diseases of the coronary arteries (calcifications)
Inflammation of the heart muscle
Changes due to medication
Electolytic disorders in the blood (potassium, calcium)