Stress Echocardiography in the Diagnosis and Evaluation of Pulmonary Hypertension: Practical Recommendations, Haemodynamic Phenotyping, and Application in Adults and Children.

Pulmonary hypertension (PH) is a complex condition in which early diagnosis remains challenging, particularly in patients with exertional symptoms and normal or borderline resting haemodynamics. Although right heart catheterisation is the diagnostic gold standard, transthoracic echocardiography is the recommended first-line non-invasive test. However, resting echocardiography provides only a static assessment and may underestimate disease severity in early or latent pulmonary vascular disease due to preserved pulmonary vascular compliance and adaptive right ventricular responses. Because pulmonary haemodynamics are intrinsically flow-dependent, pathological abnormalities may only emerge during increased cardiac output. Stress echocardiography, performed using exercise or pharmacological stress, enables dynamic evaluation of pulmonary pressure responses, cardiac output augmentation, right ventricular contractile reserve, and ventricular interaction. Increasing evidence indicates that stress echocardiography can unmask abnormal pulmonary pressure-flow relationships, impaired pulmonary vascular reserve, and reduced right ventricular-pulmonary arterial coupling that are not apparent at rest, thereby improving functional and haemodynamic characterisation in selected patients. This Diagnostic Review outlines the physiological basis for stress echocardiographic assessment of pulmonary circulation, proposes practical recommendations for patient selection and testing protocols, and provides a framework for interpretation centered on pressure-flow relationships rather than absolute pulmonary pressure thresholds. Particular attention is given to clinical scenarios with high diagnostic yield, including unexplained exertional dyspnoea, systemic sclerosis, suspected heart failure with preserved ejection fraction, at-risk relatives of patients with pulmonary arterial hypertension, selected athletes, and paediatric populations. Stress echocardiography should not be considered a standalone diagnostic test for PH but, when performed in experienced centers and integrated within structured diagnostic pathways, it represents a valuable non-invasive adjunct to guide referral for invasive haemodynamic confirmation.