An electrocardiogram (ECG or EKG, from the German spelling) is a medical test that records the electrical activity of the heart. Small electrode patches attached to the chest, arms, and legs detect electrical signals as the heart beats, producing a characteristic wave pattern on paper or screen. Doctors analyze these patterns to detect heart rhythm problems (arrhythmias), evidence of heart attacks (current or previous), heart muscle abnormalities, and other cardiac conditions. Standard ECGs are quick, painless tests taking just minutes, available at most medical facilities. Extended monitoring options include Holter monitors worn for 24-48 hours to catch intermittent problems. ECG testing is covered by provincial health insurance when ordered by healthcare providers. This fundamental cardiac diagnostic tool helps guide treatment decisions for millions of Canadians with heart conditions.