In acute pulmonary embolism, which among the following is the MOST frequent ECG finding?

ECG is abnormal 70% of patients with pulmonary embolism and sinus tachycardia is the most common noted change. But these ECG changes are usually non specific. Other ECG findings that may relate to the effect of pulmonary embolus on the right ventricular and right atrial pressure and function are right bundle branch block, large R wave in lead V1, right axis detion, T wave inversion in V1-4, P pulmonale and atrial arrhythmias. Combination of S in V1 and a Q wave and inveed T wave in lead III gives SI QIII TIII pattern suggestive of right ventricular strain. This ECG pattern is repoed in 12% of PE patients. Ref: Practical ECG Interpretation: Clues to Hea Disease in Young Adults By George Stouffer page 131.