**Core Concept**
In acute pulmonary embolism (PE), the ECG changes are a result of the sudden increase in pulmonary artery pressure, which can lead to right ventricular strain and ischemia. The ECG findings in PE can be nonspecific but often reflect the strain on the right ventricle.

**Why the Correct Answer is Right**
The ECG changes in PE can include sinus tachycardia, right axis deviation, and S1Q3T3 pattern, which is a classic ECG finding in PE. The S1Q3T3 pattern is characterized by a deep S wave in lead I, a Q wave in lead III, and an inverted T wave in lead III. This pattern is thought to be due to the increased pressure in the pulmonary artery, which causes the right ventricle to strain and become ischemic.

**Why Each Wrong Option is Incorrect**
**Option A:** S1Q3T3 pattern is indeed a classic ECG finding in pulmonary embolism.
**Option B:** Tachycardia is a common finding in pulmonary embolism due to the body's stress response to the sudden increase in pulmonary artery pressure.
**Option C:** Right axis deviation can occur in pulmonary embolism due to the strain on the right ventricle.

**Clinical Pearl / High-Yield Fact**
The ECG changes in pulmonary embolism can be subtle and nonspecific, making it essential to consider the clinical context and risk factors for PE when interpreting ECG findings.

**Correct Answer:** D.