From the Guidelines
Myocarditis can indeed cause secondary mitral regurgitation, as the inflammation and subsequent ventricular remodeling can disrupt the normal functioning of the mitral valve apparatus. This is because myocarditis, which is inflammation of the heart muscle, can lead to left ventricular dilation and dysfunction, altering the normal geometry of the mitral valve apparatus [ 1 ]. The ventricular remodeling that occurs as a result of myocarditis can prevent the mitral valve leaflets from properly coapting during systole, resulting in backward flow of blood from the left ventricle into the left atrium, known as mitral regurgitation.
The mechanism of secondary mitral regurgitation in myocarditis is similar to what occurs in dilated cardiomyopathy, where the papillary muscles are displaced laterally and apically due to ventricular enlargement, creating tension on the chordae tendineae and restricting proper valve closure. According to the 2022 AHA/ACC/HFSA guideline for the management of heart failure [ 1 ], optimization of guideline-directed medical therapy (GDMT) can improve secondary mitral regurgitation associated with left ventricular dysfunction and may obviate the need for intervention.
Key Considerations
- The mitral regurgitation may improve if the myocardial inflammation resolves and ventricular function recovers, but in cases of permanent ventricular remodeling, the valve dysfunction may persist and potentially require surgical intervention if severe [ 1 ].
- Treatment typically focuses on addressing the underlying myocarditis with anti-inflammatory medications, heart failure therapies (ACE inhibitors, beta-blockers, diuretics), and in severe cases, temporary mechanical circulatory support.
- Patient-centric conversation with a multidisciplinary cardiovascular team that includes a cardiologist with expertise in heart failure is essential when considering mitral valve intervention [ 1 ].
- Transcatheter edge-to-edge mitral valve repair has been shown to be beneficial in patients with persistent symptoms despite GDMT, appropriate anatomy on trans-esophageal echocardiography, and with left ventricular ejection fraction (LVEF) between 20% and 50%, left ventricular end-systolic diameter (LVESD) ≤70 mm, and pulmonary artery systolic pressure ≤70 mm Hg [ 1 ].
Management Approach
- Optimization of GDMT is crucial in managing secondary mitral regurgitation, and reassessment of mitral regurgitation should be performed before considering mitral valve interventions [ 1 ].
- Surgical or transcatheter repair may be considered in patients with persistent severe secondary mitral regurgitation despite GDMT, depending on the clinical scenario [ 1 ].
- The optimal management of secondary mitral regurgitation may depend on the degree of mitral regurgitation relative to left ventricular remodeling, with disproportionate mitral regurgitation potentially responding better to procedural interventions [ 1 ].
From the Research
Causes of Secondary Mitral Regurgitation
- Secondary mitral regurgitation is a result of left atrial or left ventricular dysfunction 2
- It can be caused by multifactorial left atrioventricular dysfunction and maleficent remodelling 3
- The disease is related to dilation of the left ventricle and/or mitral annulus, commonly resulting in concomitant restriction of the leaflets 4
Relationship between Myocarditis and Secondary Mitral Regurgitation
- There is no direct evidence in the provided studies to suggest that myocarditis can cause secondary mitral regurgitation
- However, it is known that left ventricular dysfunction, which can be caused by myocarditis, can lead to secondary mitral regurgitation 4, 3
Management of Secondary Mitral Regurgitation
- The management of secondary mitral regurgitation is complex and requires a multidisciplinary Heart Team approach 5
- Optimization of pharmacological and device therapy according to guideline recommendations is crucial 5
- Transcatheter repair has emerged as a promising alternative to surgical correction, but the conflicting results of current randomized trials require careful interpretation 3, 5