Controversies in pulmonary hypertension due to left heart disease

Left heart failure is currently the most prevalent cause of pulmonary hypertension (PH) worldwide and this is due mainly to the increased left ventricular and pulmonary venous pressures seen in this condition. Still, a quota of patients with left heart failure will have a pulmonary arterial disease "disproportionate" to the initial increase of left-sided pressures. Whatever the mechanism involved, the appearance of PH is a powerful marker, as it determines decreased exercise tolerance and survival. To date, all trials using therapies approved for pulmonary arterial hypertension (PAH) failed to demonstrate a benefit in the context of heart failure (HF) without or with PH. In addition, the comparison among studies is limited by relevant differences in definitions, methodology, and timing of assessment. A novel rigorous hemodynamic classification based on the diastolic pulmonary gradient has been recently proposed to better characterize this form of PH. This will promote uniformity in patient populations and end-points for future clinical trials.