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
In acute pulmonary embolism, the most frequent ECG finding is : 
Select and explain. 
A. S1Q3T3 pattern, B. P. pulmonale, C. Sinus tachycardia, D. Right axis detion
C: Sinus tachycardia
Answer: C: Sinus tachycardia 
Explanation: Answer is C (Sinus Tachycardia ) Sinus tachycardia is the commonest ECG abnormality in pulmonary embolism- OHCM 5th / 88 Classic Abnormalities on ECG in pulmonary Embolism Sinus Tachycardia (Commonest : OHCM) Right ventricular strain pattern (T wave inversion in leads VI to V4 perhaps most frequent - Harrison) SI QIII TIII Pattern :(Classic pattern but rare (OHCM)) Deeps S waves in lead I Q wave Inveed T wave in lead Ill New onset Atrial Fibrillation / Atrial Flutter. Right Axis Detion / RBBB.