Chronic mitral regurgitation (MR) is a common condition that, if left untreated, results in progressive heart failure, left ventricular (LV) cavity dilation and systolic dysfunction, left atrial enlargement, atrial fibrillation, and pulmonary hypertension. Although medical therapy may provide some symptomatic relief and is used to manage underlying ischemic heart disease and heart failure in patients with MR, it has not been shown to provide benefit in prevention of development of heart failure.¹ The current mainstay of therapy, surgical correction with mitral valve repair or replacement, is unavailable in approximately 50% of patients with severe MR due to the invasive nature of open-heart surgery and frequent presence of comorbidities in this group.² Consequently, percutaneous technologies, with the potential benefit of decreased morbidity, improved recovery time, and shorter hospital stay, provide an exciting treatment option for this patient population.

The 2 broad categories of mechanisms of MR include degenerative and functional MR.

Degenerative MR (dMR) implies presence of a primary anatomic abnormality involving the valve, which usually stems from 2 major groups of causes: (1) Barlow disease (myxomatous valve disease, mitral valve prolapse, or floppy valve) or (2) fibroelastic deficiency. Barlow disease typically presents earlier, with surgical referral at 40 to 50 years of age, and involves chordal elongation and thickening, thick leaflets with excessive tissue, and multiple segments of prolapse or flail. Fibroelastic deficiency tends to be seen in elderly patients (age ≥65 years), who have a brief history of MR and often present with a ruptured chord and leaflets that are thin, sparse, and frail except in prolapsing segment, which may be thickened. With single-leaflet prolapse or flail, often the P2 segment is affected.³ Other rare causes of dMR include Marfan syndrome, Ehlers-Danlos syndrome, and osteogenesis imperfecta.³

Functional MR (fMR) is caused by geometric derangement of the mitral valve apparatus secondary to LV remodeling in the setting of regional or global LV dysfunction and in the absence of a primary leaflet pathology, such that an imbalance between the closing (LV contractility, electrical synchrony, and annular contraction) and tethering (papillary muscle displacement, LV remodeling, and annular dilation) forces of the functional mitral unit are present.⁴ The most common etiologies of fMR are nonischemic (often global dilation) and ischemic (often regional dilation) dilated cardiomyopathy.⁵

Numerous technologies are aiming to address percutaneous treatment of chronic MR, and MitraClip (Abbot Laboratories, Abbott Park, IL) remains the best studied and most widely used system for percutaneous mitral valve repair. A V-shaped clip (MitraClip) that is attached to the mitral leaflets is delivered through a 24-Fr steerable delivery guide catheter via a transseptal approach. This effectively achieves a repair similar to the Alfieri stitch. Additional clips can be delivered adjacent to the original one in cases with significant residual regurgitation. This device is approved by the US Food and Drug Administration (FDA) for treatment of severe dMR and is being studied in the ongoing COAPT and RESHAPE-HF trials for its utility in the treatment of fMR.⁶

Another emerging approach involves percutaneous mitral valve replacement, as exemplified by the Tendyne system (Tendyne Medical, Baltimore, MD), formerly known as the Lutter prosthesis. The device is a self-expanding nitinol-stented valve for transapical implantation, which uses an extracardiac apical anchor, to which a tether is attached in order to stabilize the prosthetic valve in position.⁷ Specific procedural considerations for the use of these example technologies in the 2 etiologies of MR (dMR vs. fMR) are outlined here.

A 90-year-old female patient with history of coronary artery disease (CAD) and prior coronary artery bypass surgery (CABG), chronic kidney disease (CKD), heart failure with preserved ejection fraction, and 3 recent heart failure admissions was referred for evaluation. An echocardiogram revealed severe 4+ MR and pulmonary hypertension with right ventricular systolic pressure of 70 mm Hg. She was deemed a poor surgical candidate due to her comorbidities, and percutaneous intervention for her dMR was entertained (Figures 23-1, 23-2, 23-3, 23-4, 23-5, 23-6, 23-7, 23-8).