ECG signs that may be present include: sinus tachycardia, non-specific ST-segment and T-wave abnormalities, right axis deviation, incomplete or complete right bundle-branch block, and, less commonly, T-wave inversion in leads V1–V3, P pulmonale, or the classical S1, Q3, T3 (S wave in lead 1, Q wave in lead 3, and T-wave inversion in lead 3).