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
A 65 year old man presents with severe chest pain and difficulty in breathing. His ECG showed S1Q3T3 pattern with sinus tachycardia. The above ECG suggest the following diagnosis: 
Select and explain. 
A. Ventricular fibrillation, B. Acute pulmonary embolism, C. Second degree hea block, D. Atrial fibrillation
B: Acute pulmonary embolism
Answer: B: Acute pulmonary embolism 
Explanation: S1Q3T3 pattern with sinus tachycardia is characterestic of acute pulmonary embolism ie: an s wave in lead I, a Q wave in lead III and an inveed T wave in lead III. These findings are specific but insensitive. and the most common abnormality is T wave inversion in leads V1 to V4. Ref: Harrisons principles of internal medicine, 18th edition, Page: 2172.