What is the cause of chest discomfort and dyspnea (difficulty breathing) when walking?

Exertional Chest Discomfort and Dyspnea: Cardiac Ischemia Until Proven Otherwise

This presentation is classic for stable angina pectoris due to coronary artery disease—substernal chest pressure with dyspnea triggered by exertion (walking, climbing), relieved by rest within minutes, represents myocardial ischemia from inadequate coronary blood flow during increased oxygen demand. 1

Primary Diagnosis: Stable Angina/Coronary Artery Disease

The combination of exertional chest discomfort plus dyspnea that resolves with rest is the hallmark presentation of myocardial ischemia 1. This occurs when coronary artery stenosis limits oxygen delivery to the myocardium during physical activity, creating a supply-demand mismatch 1.

Key Clinical Features Supporting Cardiac Ischemia:

• Predictable exertional trigger (walking uphill, physical activity) 1, 2
• Substernal chest pressure/discomfort (not sharp pain) 1
• Associated dyspnea during the episode 1
• Relief within minutes by rest 1, 2
• Relief with sublingual nitroglycerin (when available) 1

Differential Diagnoses to Consider

While cardiac ischemia is most likely, the differential for exertional chest discomfort with dyspnea includes:

Cardiac Causes (Most Common):

• Coronary artery disease/stable angina (primary consideration) 1
• Heart failure with preserved ejection fraction (dyspnea predominates with activity) 3, 4
• Valvular heart disease (aortic stenosis causes exertional angina even without coronary disease) 1
• Cardiomyopathy (ischemic or non-ischemic) 1

Pulmonary Causes:

• COPD (produces "air hunger" and "inability to get deep breath" through dynamic hyperinflation) 1, 4
• Asthma (characterized by "chest tightness" rather than pressure) 3, 4
• Pulmonary vascular disease (stimulates vascular receptors, increases dead space) 3, 4
• Interstitial lung disease (restrictive pattern with exertional limitation) 3

Other Causes:

• Severe anemia (reduces oxygen-carrying capacity, causing tissue hypoxia despite normal lungs) 3, 4
• Deconditioning (common but diagnosis of exclusion) 3, 4

Diagnostic Approach Algorithm

Step 1: Initial Clinical Assessment

Look specifically for:

• Cardiovascular risk factors: hypertension, hyperlipidemia, smoking, diabetes, family history 1
• Physical examination findings: blood pressure, heart rate, jugular venous distension, cardiac murmurs, lung sounds (wheezing, crackles), peripheral edema 1, 4
• Use of accessory muscles during breathing 4

Step 2: First-Line Diagnostic Tests

Order immediately:

• Resting electrocardiogram (may show ischemic changes, prior infarction, or be normal) 1, 4
• Chest radiograph (evaluates cardiac silhouette, pulmonary congestion, lung parenchyma) 1, 4
• Complete blood count (rules out anemia) 4
• Basic metabolic panel (assesses for metabolic acidosis) 4
• Pulse oximetry (screens for hypoxemia) 4

Step 3: Cardiac-Specific Testing (When Ischemia Suspected)

Echocardiography should be performed in all patients with dyspnea of suspected cardiac origin to assess structure, function, and valvular disease 1. This is rated as "usually appropriate" (rating 9/9) for dyspnea with suspected cardiac origin 1.

For patients with exertional symptoms and intermediate pretest probability:

• Stress testing (exercise ECG, stress echocardiography, or myocardial perfusion imaging) to provoke and document ischemia 1
• Coronary CT angiography (non-invasive anatomic assessment of coronary arteries) 1
• Cardiac catheterization remains gold standard for definitive coronary anatomy 1

Step 4: When Diagnosis Remains Unclear

• B-natriuretic peptide (BNP) helps distinguish cardiac from pulmonary dyspnea 3, 4
• Spirometry evaluates for obstructive or restrictive lung disease 4
• Cardiopulmonary exercise testing (CPET) is the definitive noninvasive tool to differentiate cardiac, pulmonary, vascular, and deconditioning causes 3, 4

Critical Clinical Caveats

History and physical examination establish the diagnosis in 66% of cases—do not skip this fundamental step 4. The pattern of symptoms (exertional, relieved by rest) is more diagnostically valuable than any single test 1, 2.

Chest pain predictably exertional with cardiac risk factors mandates cardiac evaluation with troponin measurement and stress testing, even if resting ECG is normal 2. The case presentation in 1 demonstrates this exact scenario—normal resting ECG but positive stress test revealing ischemia.

Dyspnea predicts mortality more strongly than objective measures like FEV1 in many conditions—never dismiss symptoms because initial testing appears normal 3. Accompanying dyspnea with chest discomfort independently predicts cardiovascular and all-cause mortality 5.

The quality of chest discomfort provides diagnostic clues: "chest tightness" suggests bronchoconstriction/asthma 3, 4, while "chest pressure" with "air hunger" suggests cardiac ischemia or heart failure 1, 3.

Common Pitfall to Avoid

Do not assume pulmonary disease is the cause simply because dyspnea is prominent. Cardiac ischemia commonly presents with dyspnea as the predominant or equivalent symptom 1. The American College of Radiology guidelines specifically address "dyspnea of suspected cardiac origin" because this overlap is so common 1.

Pulmonary embolism can mimic acute coronary syndrome with chest discomfort and dyspnea, particularly in patients with ECG changes 6. However, the chronic, predictably exertional pattern described in the question makes PE unlikely.