World Health Organization (WHO) groups of pulmonary hypertension (PH) and cardiovascular magnetic resonance (CMR)
| Group 1 | Group 2 | Group 3 | Group 4 | Group 5 | |
| PH category | PAH | Pulmonary venous hypertension due to left-heart disease | PH due to lung disease | PH due to chronic thromboembolism | PH due to multifactorial or miscellaneous cause |
| Major causes | Idiopathic Heritable CTD HIV Drug/toxin induced Shunts (CHD) | Left heart disease (left-ventricular systolic and diastolic dysfunction) Valvular heart disease (mitral, aortic) | ILD COPD Sleep apnoea | Chronic thromboembolism | Myeloproliferative disorders Sarcoidosis Glycogen storage disease Chronic haemolytic anaemia Thyroid disease Chronic kidney disease |
| Diagnostic criteria by RHC | Mean PAP >20 mmHg PAWP ≤15 mmHg PVR ≥3 Wood units | Mean PAP >20 mmHg PAWP >15 mmHg PVR <3 or ≥3 Wood units | Mean PAP >20 mmHg PAWP ≤15 mmHg PVR ≥3 Wood units | Mean PAP >20 mmHg PAWP ≤15 mmHg PVR ≥3 Wood units | Presence of both precapillary and/or postcapillary PH Mean PAP >20 mmHg; PAWP ≤15 mmHg; PVR ≥3 Wood units or Mean PAP >20 mmHg; PAWP >15 mmHg; PVR <3 or ≥3 Wood units |
| Major diagnostic findings by CMR | Aberrant pulmonary veins Shunts | Left ventricular hypertrophy Left ventricular dysfunction Dilated left atrium Valvular disease Pulmonary vein stenosis | Gross fibrosis of the lung parenchyma | Thrombus in the pulmonary vessel | Lymphadenopathy Absence of spleen Focal LGE (sarcoidosis) |
| Essential diagnostic CMR modality | Dedicated cardiac views Flow mapping (phase contrast flow velocity and/or 4-D flow analysis) MRA | Short and/or long axis views cine SSFP LGE Valve lesion quantification | Cine SSFP Flow (phase contrast flow velocity or flow analysis) MRA | MRA | LGE |
| CMR prognostic focus | Short and/or long axis views cine SSFP Right ventricular function Right ventricle–pulmonary artery coupling | ||||
PAH: pulmonary arterial hypertension; CTD: connective tissue disorder; CHD: congenital heart disease; ILD: interstitial lung disease; COPD: chronic obstructive pulmonary disease; RHC: right-heart catheterisation; PAP: pulmonary arterial pressure; PAWP: pulmonary artery wedge pressure; PVR: pulmonary vascular resistance; LGE: late gadolinium enhancement; MRA: magnetic resonance angiography; SSFP: steady-state free procession.