Can mitral regurgitation (MR) cause pulmonary hypertension (PH)?

From the Guidelines

Yes, mitral regurgitation can cause pulmonary hypertension, as evidenced by the guidelines on the management of valvular heart disease, which suggest that surgery should be considered in asymptomatic patients with preserved LV function and new onset of pulmonary hypertension (systolic pulmonary pressure at rest >50 mmHg) 1. When the mitral valve doesn't close properly, blood flows backward from the left ventricle into the left atrium during contraction. This backflow increases pressure in the left atrium, which then transmits backward into the pulmonary veins and pulmonary circulation. Over time, this elevated pressure in the pulmonary vasculature leads to pulmonary hypertension. The severity of pulmonary hypertension typically correlates with the degree of mitral regurgitation, its duration, and how well the heart compensates. In chronic cases, the pulmonary vasculature undergoes remodeling with thickening of vessel walls, further elevating pulmonary pressures. This mechanism represents a common form of pulmonary hypertension classified as WHO Group 2, which is due to left heart disease. Some key points to consider in the management of mitral regurgitation and pulmonary hypertension include:

• The guidelines suggest that surgery is indicated in symptomatic patients with LVEF >30% and LVESD <55 mm 1.
• Surgery should be considered in asymptomatic patients with preserved LV function and new onset of atrial fibrillation or pulmonary hypertension (systolic pulmonary pressure at rest >50 mmHg) 1.
• The management of asymptomatic patients is controversial, but surgery can be proposed in selected asymptomatic patients with severe MR, in particular when repair is likely 1.
• Treatment primarily focuses on addressing the underlying mitral valve dysfunction, which may include medications to reduce cardiac workload or surgical intervention such as mitral valve repair or replacement in severe cases 1. It's worth noting that the guidelines emphasize the importance of considering the likelihood of successful mitral valve repair, the experience of the surgeon, and the operative risk when deciding on the management of mitral regurgitation and pulmonary hypertension 1.

From the Research

Relationship Between Mitral Regurgitation and Pulmonary Hypertension

• Mitral regurgitation (MR) can lead to pulmonary hypertension (PH) due to the increased pressure and volume overload on the left ventricle, which can eventually affect the pulmonary vasculature 2, 3, 4.
• Studies have shown that PH is a frequent occurrence in patients with MR and is associated with a poor prognosis, including higher mortality rates and adverse cardiac events 2, 3, 4, 5.
• The severity of PH is directly related to the severity of MR, with more severe MR leading to more severe PH 3, 4.

Predictors of Adverse Outcomes in Mitral Regurgitation with Pulmonary Hypertension

• Preoperative PH is a significant predictor of adverse outcomes, including mortality and cardiac events, in patients undergoing mitral valve surgery for MR 2, 4.
• The severity of PH, as measured by systolic pulmonary artery pressure (sPAP), is a strong predictor of adverse outcomes, with higher sPAP values associated with worse prognosis 2, 3, 4.
• Other predictors of adverse outcomes in MR with PH include right ventricular dysfunction, tricuspid regurgitation, and left ventricular dysfunction 5, 6.

Impact of Mitral Valve Repair on Pulmonary Hypertension

• Mitral valve repair, including transcatheter mitral valve repair (TMVR) and restrictive mitral annuloplasty (RMA), can reduce PH and improve outcomes in patients with MR 3, 4, 5.
• However, the presence of significant PH before surgery can still affect outcomes, and careful assessment of PH and other parameters is necessary before making clinical decisions for TMVR or RMA 5, 6.