Differential Diagnosis for a 50-year-old Man with Chest Pain and Shortness of Breath

Single Most Likely Diagnosis

• Chronic Stable Angina: This condition is characterized by chest pain or discomfort that occurs with exertion or stress and is relieved by rest. Given the patient's symptoms of chest pain and shortness of breath that improve with rest and his ability to continue working, this diagnosis fits well. The patient's occupation as a mechanic, which may involve physical exertion, and his age also align with risk factors for coronary artery disease, a common cause of chronic stable angina.

Other Likely Diagnoses

• Heart Failure with Reduced Ejection Fraction (HFrEF): Although the patient's symptoms improve with rest, the presence of shortness of breath and limitation in physical activity could suggest early stages of heart failure. Further evaluation would be needed to determine ejection fraction and assess for other signs of heart failure.
• Chronic Obstructive Pulmonary Disease (COPD): COPD could explain the shortness of breath, especially if the patient has a history of smoking or exposure to lung irritants. However, the chest pain component might not be as directly related to COPD unless there are associated conditions like pulmonary hypertension.

Do Not Miss Diagnoses

• Acute Coronary Syndrome (ACS): Although the patient's symptoms improve with rest, it's crucial not to miss an ACS, which includes conditions like myocardial infarction (heart attack). The intermittent nature of the symptoms could be a variant form of ACS, such as unstable angina.
• Pulmonary Embolism (PE): This is a life-threatening condition that can cause sudden onset of chest pain and shortness of breath. While the patient's symptoms seem to be exertional and improve with rest, which is less typical for PE, it's a diagnosis that cannot be missed due to its high mortality rate if untreated.

Rare Diagnoses

• Cardiac Sarcoidosis: A condition where granulomas form in the heart, potentially leading to chest pain, shortness of breath, and arrhythmias. It's less common but should be considered in the differential diagnosis, especially if other tests for more common conditions are negative.
• Hypertrophic Cardiomyopathy: A condition characterized by thickening of the heart muscle that can lead to chest pain, shortness of breath, and limitations in physical activity. It's a rare cause of these symptoms but is important to diagnose due to its implications for treatment and prognosis.

NYHA Classification

Based on the information provided, the patient's symptoms and ability to perform physical activity without significant limitation suggest an NYHA class of B. 2, indicating slight limitation of physical activity. The patient is comfortable at rest, but ordinary physical activity results in fatigue, palpitation, or shortness of breath.