The Role of Cardiac Imaging for the Evaluation of Primary and Secondary Mitral Regurgitation: From Milestones to Novelties

Abstract

Mitral regurgitation (MR) is the second most prevalent valvular heart disease, classified as primary (degenerative) or secondary (functional) based on its underlying etiology. Accurate assessment of MR severity, mechanism, and prognosis is crucial for guiding therapeutic decision-making, including surgical and transcatheter interventions. Cardiac imaging plays a pivotal role in this evaluation, wherein transthoracic and transesophageal echocardiography is considered the first-line modality. Advancements in three-dimensional echocardiography and cardiac magnetic resonance imaging allowed to refine the quantification and characterization of MR, enhancing diagnostic accuracy and risk stratification. This review aims to provide an overview of multimodal cardiac imaging and the most relevant parameters to assess MR, highlighting key milestones, novel techniques, and their implications in clinical practice.

Keywords: Cardiac magnetic resonance; echocardiography; mitral regurgitation; primary; secondary.

Figure 1

Images from a transthoracic echocardiographic examination aimed at acquiring anatomical mitral valve parameters for surgery planning. (a) Measurement of the mitral annulus diameter in apical four-chamber view, (b) Measurement of the anteroposterior diameter of the mitral annulus in apical two-chamber view, (c) Length of the anterior mitral leaflet in apical three-chamber view, (d) Coaptation point-to-septum distance in apical three-chamber view, (e) Evaluation of the mitral–aortic angle in the apical three-chamber view

Figure 2

Images from a transesophageal echocardiogram to determine the severity of the mitral valve regurgitation. (a) Measurement of the proximal isovelocity surface area (PISA) radius resulting in ≥1 cm with mitral regurgitation aliasing velocity of 30–40 cm/s, strongly indicative of severe valve defect, (b) Automatic calculation of the effective regurgitant orifice area (EROA) after acquisition of the PISA radius and Doppler continuous spectrum of the mitral regurgitation: the image shows an EROA ≥40 cm² and a regurgitant volume ≥60 ml, also indicative of severe MR, (c) Measurement of the vena contracta at the narrowest point of the maximum visible regurgitant jet: a value ≥7 mm is another indicator of severity

Figure 3

Three-dimensional transesophageal echocardiogram in a case of severe primary mitral regurgitation: in the first image (a), the mitral annulus is seen to be dilated, with measurements of its diameters; in the second image (b), the leaflets are markedly redundant, exhibiting extreme billowing during systole

Figure 4

Transthoracic echocardiogram in a setting of atrial functional mitral regurgitation. (a) Initial assessment with basic echo technique and color Doppler evidence of significant mitral regurgitation, (b) Advanced echocardiographic evaluation with left atrial strain: in this case, a reduction in PALS can be observed, suggestive of atrial fibrosis

Figure 5

Representative case of an 88-year-old patient presented to the emergency department with acute pulmonary edema. Echocardiography revealed chordal rupture at the level of P2 with flail of the posterior leaflet, resulting in severe mitral valve regurgitation (a-d). The patient underwent transcatheter edge-to-edge mitral valve repair with the implantation of two MitraClip G4 XTW and XT devices. The devices were deployed after confirmation of stability and a significant reduction in regurgitation (e-g). The final assessment showed correctly positioned clips, minimal residual regurgitation, and a mean transvalvular gradient of 4 mmHg (h). TEER: Transcatheter edge-to-edge repair

Figure 6

Evaluation with transesophageal echocardiography of severe mitral regurgitation with multiple central jets due to a combined degenerative and central tethering mechanism in the context of ischemic cardiomyopathy with left ventricular dilation and systolic dysfunction (left ventricular ejection fraction 40%) (a and b), (c) Measurement of the posterior mitral leaflet: a length >10 mm is a favorable indicator for MitraClip procedure according to COAPT criteria