From the Guidelines
Secondary mitral insufficiency is primarily caused by left ventricular dysfunction and dilation, which can result from ischemic heart disease, dilated cardiomyopathy, or hypertensive heart disease, leading to papillary muscle displacement and mitral annular dilation, preventing proper valve leaflet coaptation. The main causes of secondary mitral insufficiency include:
- Left ventricular dysfunction and dilation, which can result from ischemic heart disease (particularly after myocardial infarction), dilated cardiomyopathy, or hypertensive heart disease 1
- Left atrial dilation, often seen in atrial fibrillation, which stretches the mitral annulus and impairs valve closure
- Hypertrophic cardiomyopathy, which can cause secondary mitral insufficiency through systolic anterior motion of the mitral valve
- Right ventricular dysfunction with tricuspid regurgitation leading to septal displacement
- Certain medications or conditions that affect left ventricular function
According to the most recent guidelines, optimization of guideline-directed medical therapy (GDMT) can improve secondary mitral regurgitation associated with left ventricular dysfunction and obviate the need for intervention 1. Patients with persistent severe secondary mitral regurgitation despite GDMT may benefit from either surgical or transcatheter repair, depending on the clinical scenario. 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 between 20% and 50%, left ventricular end-systolic diameter ≤70 mm, and pulmonary artery systolic pressure ≤70 mm Hg 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 responding better to procedural interventions and proportionate mitral regurgitation responding to measures that reverse left ventricular remodeling and reduce left ventricular volumes 1.
From the Research
Causes of Secondary Mitral Insufficiency
- Secondary mitral regurgitation (SMR) is characterized by left ventricular (LV) dilatation or dysfunction, resulting in failure of mitral leaflet coaptation 2.
- The most frequently encountered cause of SMR in clinical practice is ischaemic cardiomyopathy, due to the prevalence of coronary artery disease worldwide 2.
- SMR can also complicate dilated cardiomyopathies, with a reported prevalence of up to 57% 2.
- The development of SMR is strongly associated with a poor prognosis in patients with heart failure, and is multifactorial in nature 3.
- The pathophysiology of SMR involves left atrioventricular dysfunction and maleficent remodelling, and is associated with a very poor prognosis 4.
Associated Conditions
- SMR is often associated with heart failure, and the treatment of SMR includes guideline-directed heart failure therapy along with surgical and transcatheter approaches 5.
- Coronary artery disease is a common underlying condition in patients with SMR, and revascularization may be necessary in some cases 3.
- Cardiac resynchronization therapy may also be beneficial in patients with SMR and heart failure 3.
Prognosis and Treatment
- SMR is an independent predictor of mortality and hospitalization for heart failure, and the presence of even mild SMR can reduce long-term survival free of major adverse events 2.
- The treatment of SMR is complex, and includes medical, surgical, and interventional therapies 3.
- Transcatheter mitral valve repair has shown effectiveness in certain subgroups of patients with SMR, and can improve prognosis and reduce hospitalization for heart failure 2, 4.