Introduction

Dyspnoea (shortness of breath) and chest pain are two of the most common and potentially serious presenting symptoms in clinical medicine. The challenge lies in differentiating between benign, self-limited causes and life-threatening conditions like myocardial infarction (a heart attack), pulmonary embolism(a bloot clot in the lungs), and heart failure. A structured, stepwise diagnostic approach integrating clinical assessment and targeted tests is essential for accurate diagnosis and risk stratification.

Initial evaluation: History and physical examination

The evaluation begins with a thorough history and physical examination. Clinicians should assess the onset, duration, triggers (exertion, position, time of day), associated symptoms (orthopnea, palpitations, cough, fever), and pre-existing conditions such as chronic lung or cardiac diseases. Physical signs, including wheezing, crackles, murmurs, jugular venous distension, or lower extremity oedema provide valuable clues to the underlying cause.¹

Oxygenation assessment: Pulse oximetry and arterial blood gases

Pulse oximetry provides a non-invasive measure of peripheral oxygen saturation. A small medical device is placed on the finger and measures the amount of oxygen in the blood flowing around the body. While useful, it may miss subtle abnormalities in ventilation or acid-base balance. In such cases, arterial blood gas (ABG) analysis is warranted. ABGs provide direct measurement of PaO₂, PaCO₂, pH, and bicarbonate, aiding in the diagnosis of hypoxaemia, hypercapnia, metabolic acidosis/alkalosis, and ventilatory failure.^1,2

Blood tests: CBC, BNP, and cardiac biomarkers

A complete blood count (CBC) can identify anaemia, which may contribute to dyspnea, or polycythaemia which may reflect chronic hypoxaemia. Elevated brain natriuretic peptide (BNP) or NT-proBNP levels suggest heart failure as the cause of dyspnoea and prompt further cardiac evaluation.³

Cardiac troponins are key biomarkers in chest pain evaluation. Elevated levels indicate myocardial injury and support a diagnosis of acute coronary syndrome, even when ECG findings are nondiagnostic. These markers are especially critical in patients with atypical presentations, such as dyspnoea without chest pain.^3,4

Imaging: Chest x-ray and lung ultrasound

Chest radiography (CXR) remains the first-line imaging modality for both dyspnoea and chest pain. It can identify cardiomegaly (heart enlargement), pulmonary oedema (abnormal collection of fluid in the lungs), pneumonia, pleural effusion (abnormal collection of fluid in the lung cavity), pneumothorax (lung collapse) and other abnormalities.^1,3

Lung ultrasound is increasingly used at the bedside to detect conditions like pulmonary edema (via B-lines), pleural effusions, or pneumothorax. Studies suggest that lung ultrasound may be more sensitive than CXR in some settings, particularly in identifying interstitial syndrome or small effusions.⁵

Electrocardiogram (ECG)

A 12-lead ECG is a cornerstone test in any patient with chest pain. It detects ischemic changes (ST elevation/depression, T wave inversion), arrhythmias, conduction blocks, pericarditis, and right heart strain. In dyspnea cases, ECG may reveal evidence of pulmonary hypertension or right ventricular overload, prompting further cardiac or pulmonary imaging.^3,4

Pulmonary function testing and spirometry

Spirometry is essential for evaluating obstructive lung diseases like asthma and COPD. It measures forced expiratory volume (FEV₁), forced vital capacity (FVC), and FEV₁/FVC ratio. In restrictive lung disease, both FEV₁ and FVC are reduced with a normal or high ratio.⁶

Comprehensive pulmonary function tests (PFTs), including total lung capacity and diffusing capacity of the lung for carbon monoxide (DLCO), are useful for diagnosing interstitial lung diseases, pulmonary vascular disease, or neuromuscular disorders when spirometry alone is inconclusive.^6,7

Echocardiography

Transthoracic echocardiography (TTE) is a non-invasive method to assess cardiac function and structure. It can identify reduced ejection fraction, valvular abnormalities, ventricular hypertrophy, pericardial effusion, or pulmonary hypertension. TTE is particularly useful in distinguishing cardiac from pulmonary causes of dyspnea and evaluating structural heart disease in chest pain presentations.^7,8

Stress testing

When myocardial ischemia is suspected, exercise ECG stress testing is often the first diagnostic choice in low- to intermediate-risk patients. It assesses exercise capacity and reveals ECG changes suggestive of ischemia. The Duke Treadmill Score, combining ECG changes, exercise duration, and angina, provides prognostic information.⁸

Stress echocardiography and nuclear perfusion imaging offer higher sensitivity and specificity than ECG alone, especially in patients with baseline ECG abnormalities or poor exercise capacity. These tests assess wall-motion abnormalities or perfusion deficits, respectively, during stress, helping to identify significant coronary artery disease.^8,9

Cardiopulmonary Exercise Testing (CPET)

CPET is the gold standard for evaluating unexplained dyspnoea. It measures oxygen uptake (VO₂), carbon dioxide production (VCO₂), ventilatory efficiency, and anaerobic threshold during graded exercise. CPET helps distinguish between cardiac, pulmonary, and deconditioning-related dyspnoea. It is especially useful when standard tests fail to yield a diagnosis.¹⁰

Advanced imaging and invasive hemodynamics

If pulmonary embolism (PE) is suspected, CT pulmonary angiography (CTPA) is the diagnostic gold standard. It provides direct visualization of emboli in pulmonary arteries. In patients with contraindications to contrast, a ventilation-perfusion (V/Q) scan may be used.⁴

For patients with suspected interstitial lung disease, high-resolution computed tomography (HRCT) offers detailed images of lung parenchyma, revealing fibrosis, ground-glass opacities, or emphysematous changes.

In cases of suspected pulmonary hypertension, right heart catheterization remains the gold standard for confirming elevated pulmonary artery pressures and differentiating between pre- and post-capillary hypertension.⁷

Structured diagnostic approach

A well-organized strategy is essential in clinical practice. Initially, all patients should undergo a history and physical examination, pulse oximetry, ECG, CXR, and basic laboratory work (CBC, BNP, troponins, and ABGs if indicated). If pulmonary disease is suspected, spirometry or full PFTs should follow.

If cardiac disease is likely, echocardiography is the next step. Patients with exertional chest pain should undergo stress testing, either ECG-based, echocardiographic, or nuclear imaging, depending on risk level and exercise capacity.

When symptoms persist and standard tests are inconclusive, CPET can help differentiate causes. For suspected thromboembolic disease or interstitial pathology, CTPA, V/Q scanning, or HRCT are warranted. Finally, right heart catheterization may be indicated in complex cases of pulmonary hypertension.

Summary

Evaluating dyspnea and chest pain requires an integrative, stepwise approach that combines clinical assessment with targeted diagnostic testing. A range of non-invasive and invasive tools from pulse oximetry to advanced imaging enables accurate diagnosis, helps determine disease severity, and guides timely treatment. Applying these tests judiciously ensures optimal patient care, avoids unnecessary testing, and improves outcomes.