Mitral Regurgitation Part 2: Associated Comorbidities and Medical Management

Associated Comorbidities¹

• Acute MR is a hemodynamic emergency. Because the LA has not had time to adapt to the sudden increase in regurgitant volume, the rapid rise in LA pressure causes severe pulmonary venous congestion and edema. Cardiogenic shock can occur when forward cardiac output drops, making urgent intervention essential.
• Conditions that lead to acute MR often require specialty cardiothoracic consultation because definitive management is surgical, with medical therapy serving as a bridge. Common precipitating conditions of acute MR include:
  • Infective endocarditis
  • Papillary muscle rupture (often postmyocardial infarction)
  • Chordae tendineae rupture
  • Acute ischemic events
• In chronic MR, the LA and LV dilate to accommodate regurgitant volume without increasing chamber pressures. Hemodynamic parameters are frequently preserved, but patients may develop volume overload, pulmonary hypertension, and/or atrial fibrillation over time.
  • Common precipitating conditions of chronic MR include:
  • Mitral valve degeneration (myxomatous degeneration, leaflet prolapse or flail)
  • Inflammatory and infectious etiologies (rheumatic heart disease, connective tissue disorders)
  • LA/LV remodeling (ischemic/dilated cardiomyopathy, atrial fibrillation)
  • Iatrogenic etiologies (mitral annular calcification, congenital anomalies)

Management of MR²

• The management of MR depends upon the onset (acute vs. chronic) and nature (primary vs. secondary) of the regurgitant lesion.
• Acute MR is often caused by an abrupt change in valvular function due to etiologies such as endocarditis and papillary muscle or chordal rupture.
• Chronic MR results from abnormalities that progress over time, such as ischemic or dilated cardiomyopathy.
• Primary MR refers to regurgitation that results from a structural abnormality in the valve leaflets, whereas secondary MR is characterized by normal leaflet morphology but impaired function due to LA dilation (atrial functional MR) or chronic LV dysfunction and dilation leading to restricted leaflet motion.

Acute MR

• Acute MR requires rapid hemodynamic stabilization, with medical therapy serving only as a bridge to definitive surgical or transcatheter intervention. Patients often present with flash pulmonary edema and hypotension due to an abrupt rise in LA pressure.
• Vasoactive therapy includes inotropes and afterload-reducing vasodilators/inodilators to support forward cardiac output and reduce regurgitant volume. Inotropes such as dobutamine help augment contractility and maintain systemic perfusion. Afterload reduction improves forward stroke volume and decreases regurgitant flow back into the left atrium.
• Positive pressure ventilation (continuous positive airway pressure and bilevel positive airway pressure) may be utilized to treat pulmonary edema and improve oxygenation/ventilation.
• Diuretics may be administered to decrease pulmonary edema, but must be used with caution in the setting of cardiogenic shock. Close monitoring of end-organ perfusion and response is essential if diuretics are used.
• Intra-aortic balloon pump, Impella, or extracorporeal membrane oxygenation may be required in cardiogenic shock for temporary mechanical circulatory support. These devices reduce afterload and augment coronary perfusion, allowing stabilization prior to surgery.
• Urgent cardiothoracic surgery consultation is necessary to address the underlying etiology, as medical therapy is not definitive. Papillary muscle rupture, chordal disruption, or valvular destruction from endocarditis all require prompt repair or replacement.

Chronic MR

• Chronic MR is a nonemergent condition that involves various medical and surgical management strategies. Evaluation by a multidisciplinary heart valve team is recommended for all patients with severe valvular heart disease being considered for an intervention.
• Severe primary MR is managed surgically. If the operative risks of open surgery are prohibitive, guideline-directed medical therapy (GDMT) may be considered, which consists of beta blockers, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, and/or neprilysin inhibitors, aldosterone antagonists, sodium glucose cotransporter 2 inhibitors, and/or biventricular pacing if necessary.
• Patients with severe secondary MR with preserved LV function may be considered for mitral valve surgery if they remain symptomatic despite GDMT (Table 1).
• Patients with severe secondary MR and reduced LV systolic function should receive GDMT. If they are undergoing coronary artery bypass graft, it is reasonable to concurrently address the mitral valve surgically (Table 1).
• In patients with prohibitive open surgical risk and persistent heart failure symptoms despite optimal GDMT, transcatheter edge-to-edge repair may be considered (Table 1).
• Transcatheter mitral valve replacement is an emerging procedure that may be suitable for patients with prohibitive open surgical risk requiring MV repair or replacement (Table 1).