The rhythm is either sinus rhythm or not sinus rhythm. Sinus rhythm refers to the origination of the electrical activity coming from the sinus node — also known as the sinoatrial node, or SA node.

Atrial fibrillation occurs when action potentials fire very rapidly within the pulmonary veins or atrium in a chaotic manner. The result is a very fast atrial rate — about 400 to 600 beats per minute.

A new study has linked prolonged P-wave duration to increased risk for sudden cardiac death (SCD), independent of cardiovascular risk factors and atrial fibrillation. 1 This suggests P-wave duration ...