What is the relationship between mitral valve regurgitation (mitral valve leakage) and the development of pulmonary hypertension?

From the Guidelines

Mitral valve regurgitation is a significant cause of pulmonary hypertension due to the backward flow of blood into the left atrium, leading to increased left atrial pressure and subsequent transmission of this pressure into the pulmonary veins and arterial system. This relationship is well-established in the context of heart failure, as noted in a scientific statement from the American Heart Association 1. The mechanism involves the mitral valve apparatus's incompetence, allowing retrograde flow of blood from the ventricle to the atria during systole, which can arise from various cardiovascular diseases affecting the mitral valve structures.

Key points to consider in this relationship include:

• The regurgitant fraction, which is the ratio of the regurgitant volume to the total stroke volume, is a critical parameter in assessing the severity of mitral regurgitation and its potential to lead to pulmonary hypertension.
• Chronic and severe mitral regurgitation can lead to progressive left ventricular dilation, enlargement of the left atrium, and increased pulmonary venous pressures, ultimately resulting in signs and symptoms of heart failure.
• The development of pulmonary hypertension in this context is a result of the increased pressure transmitted back into the pulmonary circulation, which can lead to right heart failure if left untreated.

In managing patients with mitral valve regurgitation and pulmonary hypertension, it is essential to consider both the severity of the valvular disease and the extent of pulmonary hypertension. Treatment strategies may include:

• Medications such as diuretics, ACE inhibitors, and beta-blockers to manage symptoms and reduce cardiac workload.
• Surgical intervention, including mitral valve repair or replacement, for moderate to severe cases.
• Regular echocardiographic monitoring to assess disease progression and the need for adjustments in treatment.
• Lifestyle modifications, including sodium restriction, fluid management, and regular exercise, to mitigate the effects of both conditions.

From the Research

Relationship Between Mitral Valve Regurgitation and Pulmonary Hypertension

The relationship between mitral valve regurgitation (mitral valve leakage) and the development of pulmonary hypertension is complex and multifaceted. Key points to consider include:

• Mitral regurgitation allows for partial transmission of systemic arterial pressure into the pulmonary venous system, leading to pulmonary venous hypertension (PVH) 2
• Chronic and severe PVH may then lead to muscularization of the pulmonary arterial bed, with a rise in pulmonary vascular resistance (PVR) and loss of pulmonary arterial compliance 2
• The presence of pulmonary hypertension in patients with mitral valve disease indicates a decompensated state of the disease with left ventricular and left atrial dysfunction and exhausted compensatory mechanisms 3
• Pulmonary hypertension in this context is the consequence of the backwards transmission of elevated left atrial pressure, with pulmonary vascular resistance initially normal (isolated post-capillary PH) 3

Predictors of Outcome in Patients with Pulmonary Hypertension Undergoing Mitral Valve Surgery

Several studies have investigated the predictors of outcome in patients with pulmonary hypertension undergoing mitral valve surgery. Key findings include:

• Pre-operative left ventricular ejection fraction (LVEF), peak systolic tissue velocity at the tricuspid annulus (S'), and etiology of mitral valve disease are associated with respiratory and renal failure 4
• Tricuspid annular plane systolic excursion (TAPSE) is associated with respiratory failure only 4
• S', type of operation, LVEF, urgency of surgery, and etiology of mitral valve disease are predictive of mortality 4
• Pulmonary hypertension is associated with increased risk of mortality after mitral valve surgery for mitral regurgitation 5
• The association of pulmonary hypertension with mortality persists despite multivariable adjustment 5

Association of Pulmonary Hypertension with Clinical Outcomes

The association of pulmonary hypertension with clinical outcomes in patients undergoing transcatheter mitral valve repair has been investigated. Key findings include:

• Pulmonary hypertension is associated with increased mortality and readmission for heart failure in patients undergoing transcatheter mitral valve repair using the MitraClip system for severe mitral regurgitation 5
• The composite rate of 1-year mortality and readmissions for heart failure is higher in patients with pulmonary hypertension 5
• Significant tricuspid regurgitation and more severe degrees of pulmonary hypertension before surgery are significantly associated with the presence of persistent pulmonary hypertension after mitral valve replacement 6