P wave is absent in -

Atrial fibrillation (AF or A-fib) is an abnormal hea rhythm characterized by rapid and irregular beating of the atrial chambers of the hea.Often it stas as brief periods of abnormal beating which become longer and possibly constant over time. Often episodes have no symptoms.Occasionally there may be hea palpitations, fainting, lightheadedness, shoness of breath, or chest pain. The disease is associated with an increased risk of hea failure, dementia, and stroke.It is a type of supraventricular tachycardia Leads V4 and V5 of an electrocardiogram showing atrial fibrillation with somewhat irregular intervals between hea beats, no P waves, and a hea rate of about 150 BPM. Ref Harrison 20th edition pg 1412