Widely split P waves in the presence of interatrial block.

Interatrial block (IAB; P wave>or=110 milliseconds), conduction delay between the atria, is highly prevalent and is associated with atrial tachyarrhythmias, left atrial electromechanical dysfunction, as well as a potential risk for systemic embolism. However, much is still yet to be known of IAB's exact pathophysiology and how it may manifest in relation to medical disease. We present an unusual case of widely split P waves in the presence of IAB in a severely ill patient.