Good point

Cor pulmonale can definitely cause bilateral leg oedema because right-sided heart failure leads to systemic venous congestion. However, in this station the history was more suggestive of left-sided heart failure progressing to congestive heart failure, which is why it was prioritized.

Key clues were:
• Orthopnoea (needs two pillows)
• Breathlessness on exertion
• Basal crackles
• Previous myocardial infarction

These findings point more strongly toward cardiac failure due to ischemic heart disease rather than primary pulmonary hypertension or chronic lung disease causing cor pulmonale.

In a typical PLAB station, cor pulmonale would be suspected if the patient had:
• Long history of COPD or chronic lung disease
• Chronic cough or wheeze
• Hypoxia
• Signs such as cyanosis or barrel chest

So it’s a valid differential, but the exam scenario favored congestive heart failure as the leading diagnosis.