Pulmonary arterial hypertension (PAH) is defined as a mean pulmonary artery pressure (mPAP) ≥ 25 mmHg at rest. According to the World Health Organization (WHO) classification of PAH, pulmonary hypertension associated with left heart disease belongs to category II, which is caused by left ventricular systolic dysfunction, left ventricular diastolic dysfunction, and/or left heart valve disease. wedge pressure (PCWP) >15 mmHg, which is the most common type of pulmonary hypertension. The incidence of PH is related to the degree of left heart insufficiency. PH is combined in 60% of patients with left heart systolic dysfunction and 70% of those with diastolic insufficiency alone. In recent years, this type of pulmonary hypertension has received increasing attention. It is an independent predictor of prognosis in patients with left heart failure. At present, research on pulmonary hypertension associated with left heart disease is still in its infancy, and much work remains to be done in its pathogenesis, diagnosis, treatment and prognosis. Pulmonary hypertension associated with left heart disease is divided into reactive and passive. Reactive pulmonary hypertension occurs with a poor prognosis, and the mechanisms are still unclear. Are vasoactive substances such as endothelin, nitric oxide and prostacyclin also involved in the development of this type of pulmonary hypertension? Are there genetic mechanisms, inflammatory mechanisms, and energy metabolic mechanisms involved in the development of this type of pulmonary hypertension? These questions remain to be explored. Identification of the mechanisms involved in the development of this type of pulmonary hypertension may guide pharmacological interventions to improve its prognosis. Right heart catheterization should be the diagnostic method of choice when enrolling patients in this type of study to ensure accurate diagnosis in the study population. Although a simple scoring system for the prognosis of pulmonary hypertension associated with left heart disease has been established based on the Cox risk proportional model, this study included patients from only 2 centers and 90% were in left heart failure with normal ejection fraction, so this scoring system cannot yet be extended to all patients with pulmonary hypertension associated with left heart disease, and a large sample, multicenter study is needed to include more comprehensive Therefore, this scoring system cannot be extended to all patients with pulmonary hypertension associated with left heart disease. Targeted agents (endothelin receptor antagonists, prostacyclin, and type 5 phosphodiesterase inhibitors) are currently the mainstay of treatment for PAH. The use of pharmacological interventions to improve pulmonary vascular resistance, pulmonary artery pressure and right heart function could theoretically improve the prognosis of patients with pulmonary hypertension associated with left heart disease, but there are no randomized controlled trials of clinical studies confirming the use of targeted drugs for PAH. Studies have shown that the use of endothelin receptor antagonists, prostacyclin drugs reduces pulmonary artery pressure and thus left ventricular end-diastolic pressure, reflexively causing acute left heart failure. Some studies have shown that short-term treatment of sildenafil for pulmonary hypertension associated with chronic force failure may improve the patient’s condition. Therefore, the administration of targeted drugs for pulmonary hypertension is not routinely recommended in these patients.