Question: What is the finding on this ECG and what diagnosis does it suggest?

Answer: S1Q3T3 which can commonly be seen in pulmonary embolism. This means an S wave in lead I, Q wave and an inverted T wave in lead III. Other findings are sinus tachycardia, PR displacement, late R in aVR, slurred S in V1 or V2, and a T-wave inversion in V1 or V2.

Other signs are: P. pulmonale, right ventricular hypertrophy, right axis deviation, or right bundle branch block occurred. (these were <= 6% in one study – Stein. (1991). Clinical, laboratory, roentgenographic, and electrocardiographic findings in patients with acute pulmonary embolism and no pre-existing cardiac or pulmonary disease. Chest., 100(3), 598–603. https://doi.org/10.1378/chest.100.3.598)