Pulmonary hypertension (PH) associated with left heart disease (PH-LHD) is the most common type of PH, but its natural history is not well understood. PH-LHD is diagnosed by right heart catheterisation with a mean pulmonary arterial pressure â©Ÿ25 mmHg and a pulmonary capillary wedge pressure >15 mmHg. The primary causes of PH-LHD are left ventricular dysfunction of systolic and diastolic origin, and valvular disease. Prognosis is poor and survival rates are low. Limited progress has been made towards specific therapies for PH-LHD, and management focuses on addressing the underlying cause of the disease with supportive therapies, surgery and pharmacological treatments. Clinical trials of therapies for pulmonary arterial hypertension in patients with PH-LHD have thus far been limited and have provided disappointing or conflicting results. Robust, long-term clinical studies in appropriate target populations have the potential to improve the outlook for patients with PH-LHD. Herein, we discuss the knowledge gaps in our understanding of PH-LHD, and describe the current unmet needs and challenges that are faced by clinicians when identifying and managing patients with this disease. @ERSpublications Pulmonary hypertension due to left heart disease is associated with multiple unmet medical needs http://ow.ly/TFET8Case study part 1: initial assessment A 63-year-old male with hypertension, diabetes mellitus, dyslipidaemia, coronary artery disease and obstructive sleep apnoea presented to the clinic with worsening dyspnoea upon exertion (World Health Organization (WHO) functional class IIIb). Echocardiography revealed a normal-sized left ventricle, left ventricular ejection fraction (LVEF) of 35-40%, delayed left ventricular diastolic relaxation, normal left atrium, right ventricular dilation with moderately depressed systolic function, mild right atrial enlargement, flattened interventricular septum, dilated inferior vena cava, and a pulmonary artery systolic pressure of 85 mmHg. Computed tomography pulmonary angiography revealed no pulmonary embolus or parenchymal lung disease. The patient failed to reach the target heart rate in a treadmill exercise test, but there was no evidence of myocardial ischaemia. Pulmonary function testing and right heart catheterisation (RHC) were performed (table 1).Question 1: Based on these data, what would be your initial assessment of this patient? This real-life patient case study highlights some of the many factors that can make diagnosing pulmonary hypertension associated with left heart disease (PH-LHD) challenging. Based on the information presented, would you diagnose this patient with PH-LHD?