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Estimated global distribution of the most prevalent forms of
Globally, left-sided heart failure, particularly heart failure with preserved ejection fraction, is becoming a leading cause of pulmonary hypertension, probably affecting 5–10% of individuals aged 65 years or older
Diagnostic Algorithm for PAH
The diagnostic algorithm is the diagnostic process starts after the suspicion of PH and echocardiography compatible with PH and continues with the identification of the more common clinical groups of PH [group 2 (LHD) and group 3 (lung diseases)], then distinguishes group 4 (CTEPH) and finally makes the diagnosis and recognizes the different types in group 1 (PAH) and the rarer conditions in group 5.
PAH should be considered in the differential diagnosis of exertional dyspnoea, syncope, angina and/or progressive limitation of exercise capacity, particularly in patients without apparent risk factors, symptoms or signs of common cardiovascular and respiratory disorders. Special awareness should be directed towards patients with associated conditions and/or risk factors for the development of PAH, such as family history, CTD, CHD, HIV infection, portal hypertension or a history of drug or toxin intake known to induce PAH. In everyday clinical practice, such awareness may be low.
More often PH is found unexpectedly on transthoracic echocardiography requested for another indication. If transthoracic echocardiography is compatible with a high or intermediate probability of PH, a clinical history, symptoms, signs, ECG, chest radiograph, pulmonary function tests (PFTs, including DLCO, arterial blood gases analysis and nocturnal oximetry, if required) and high-resolution CT of the chest are requested to identify the presence of group 2 (LHD) or group 3 (lung diseases) PH.
In case of an echocardiographic low probability of PH, no additional investigations are required and other causes for the symptoms should be considered together with follow-up. If the diagnosis of left heart or lung diseases is confirmed, the appropriate treatment for these conditions should be considered.
In the presence of severe PH and/or RV dysfunction, the patient should be referred to a PH expert centre where additional causes of PH can be explored. If the diagnosis of left heart or lung diseases is not confirmed, a V/Q lung scan should be performed for the differential diagnosis between CTEPH and PAH. Concurrently the patient should be referred to a PH expert centre.
If the V/Q scan shows multiple segmental perfusion defects, a diagnosis of group 4 (CTEPH) PH should be suspected. The final diagnosis of CTEPH (and the assessment of suitability for PEA) will require CT pulmonary angiography, RHC and selective pulmonary angiography. The CT scan may also show signs suggestive of group 1′ (PVOD).
If a V/Q scan is normal or shows only subsegmental ‘patchy’ perfusion defects, a diagnosis of group 1 (PAH) or the rarer conditions of group 5 should be considered. Further management according to the probability of PH is given, including indications for RHC.
Additional specific diagnostic tests, including haematology, biochemistry, immunology, serology, ultrasonography and genetics, will allow the final diagnosis to be refined. Open or thoracoscopic lung biopsy entails a substantial risk of morbidity and mortality. Because of the low likelihood of altering the diagnosis and treatment, a biopsy is not recommended in PAH patients. The pulmonary arterial hypertension screening programme is reported in the Web Addenda.