This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Absent P Wave is seen in: 
Select and explain. 
A. Atrial Fibrillation, B. Cor-pulmonale, C. Mitral Stenosis, D. COPD
A: Atrial Fibrillation
Answer: A: Atrial Fibrillation 
Explanation: Answer is A (Atrial Fibrillation) P wave is typically absent in Atrial Fibrillation. COPD and Cor-Pulmonale are associated with tall p waves from Right Atrial Enlargement (P-Pulmonale) while Mitral Stenosis is typically associated with a wide and notched p wave from Left Atrial Enlargement (P-Mitrale) Causes of Absent Wave: Atrial fibrillation (p' wave is absent or replaced by fibrillary T wave) Atrial flutter (p' wave is replaced by flutter wave, which shows saw-tooth appearance). SA block or sinus arrest Nodal rhythm (usually abnormal, small p wave). Ventricular ectopic and ventricular tachycardia. Supraventricular tachycardia (p' wave is hidden within QRS, due to tachycardia). Hyperkalemia. Idioventricular rhythm Right Atrial Enlargement(RAE) is typically associated with tall P waves P Pulmonale (COPD and Cor-Pulmonale are associated with tall p waves from RAE) Left Atrial enlargement(LAE) is typically associated with wide P waves P Mitrale (Mitral Stenosis is typically associated with a wide and notched p wave from LAE