From the Guidelines
Coronary artery dissection can cause functional mitral regurgitation primarily through ischemic injury to the left ventricular myocardium and papillary muscles, leading to reduced closing force on the leaflets and systolic tethering of the leaflets into the LV, as described in the basic principles of the echocardiographic evaluation of mitral regurgitation 1. This occurs when the dissection compromises blood flow to the heart muscle, resulting in myocardial ischemia or infarction in the territory supplied by the affected vessel. If this ischemia affects the posterolateral wall of the left ventricle where papillary muscles are located, it can cause papillary muscle dysfunction or rupture. Some key points to consider include:
- The papillary muscles are critical for normal mitral valve function as they connect to the mitral valve leaflets via chordae tendineae, and when damaged, they cannot properly support the mitral valve during systole, leading to incomplete closure of the valve and subsequent regurgitation of blood back into the left atrium.
- Ischemia can cause regional wall motion abnormalities and left ventricular remodeling, which alter the geometry of the mitral valve apparatus, further contributing to functional mitral regurgitation, as noted in the guidelines for the diagnosis and treatment of acute and chronic heart failure 1.
- The use of echocardiography in acute cardiovascular care is essential in evaluating the severity of mitral regurgitation and guiding treatment decisions, as recommended by the European Association of Cardiovascular Imaging and the Acute Cardiovascular Care Association 1. The most effective treatment approach for functional mitral regurgitation caused by coronary artery dissection involves optimizing medical treatment, considering surgical repair or replacement, and evaluating the need for percutaneous edge-to-edge repair in high-risk patients, as outlined in the guidelines for the diagnosis and treatment of acute and chronic heart failure 1.
From the Research
Coronary Artery Dissection and Functional Mitral Regurgitation
- Coronary artery dissection can lead to left ventricular dysfunction, which is a known cause of functional mitral regurgitation (MR) 2, 3.
- Functional MR occurs when there is a dysbalance between closing and opening forces on the mitral leaflets due to reduced left ventricular contractility, geometric distortion of the subvalvular apparatus, and global dilatation of the left ventricle and the mitral annulus 2.
- Ischemic cardiomyopathy, resulting from coronary artery dissection, can cause left ventricular dysfunction and subsequent congestive heart failure (CHF) and ischemic mitral regurgitation (IMR) 3.
- The underlying pathology of IMR is attributed to a dysfunctional left ventricle, and even mild IMR has been shown to be harmful to CHF patients 3.
Mechanism of Functional Mitral Regurgitation
- Functional MR can be classified into two types: ventricular functional MR (VFMR) and atrial functional MR (AFMR) 4.
- VFMR is caused by left ventricular dilatation and/or systolic dysfunction, while AFMR is caused by mitral annular dilatation due to left atrial dilatation 4.
- Coronary artery dissection can lead to VFMR by causing left ventricular dysfunction and dilatation 2, 3.
Clinical Implications
- Functional MR has a negative impact on both symptoms and prognosis in patients with CHF and systolic left ventricular dysfunction 2.
- Treatment options for functional MR include surgical correction, cardiac resynchronization therapy (CRT), and transcatheter mitral valve repair 2, 3, 5.
- The choice of treatment depends on the severity of left ventricular dysfunction and the presence of other comorbidities 5.