A review of the pivotal role of cardiac MRI in mitral valve regurgitation

Abstract

Mitral regurgitation (MR) is the most common valvular heart disorder. 1 About 9% of the general population aged more than 75 years in the United States have MR. As the incidence of MR increases with age, the number of patients with MR who require intervention and inpatient care will only increase in the coming decades. 2 MR is divided into two categories: primary organic MR, which occurs as a result of an intrinsically abnormal mitral valve, and secondary or functional MR, which develops secondary to left ventricular (LV) dysfunction or annular dilatation prohibiting normal valve closure. 3,4 Differentiating between these phenotypes of severe MR by imaging modalities is critical to allow accurate diagnosis as well as guidance in choosing timing and type of intervention. 5 Untreated severe MR is associated with poor outcomes due to the adverse consequences of long-standing volume overload on the left ventricle. It can cause LV volume overload, which may lead to progressive dilatation of the left ventricle and left atrium, heart failure, and pulmonary hypertension. 5,6 Echocardiography and CMR play a complementary role in the diagnosis and understanding the mechanism of MR. They also help define prognosis along with the optimal treatment strategies for MR. 7,8 Decisions regarding surgical interventions, being mitral valve repair or replacement, rely on symptomatology as well as the regurgitation severity, LV ejection fraction (LVEF), and LV end-systolic diameter (LVESD). 9,10 The role of imaging is hence as follows: to identify the etiology of the MR; to quantify the severity of the regurgitation; to assess the response of the left ventricle to the volume overload; and to determine the feasibility of durable repair. 4,5,7,8 Transthoracic echocardiography (TTE) remains the first-line modality per the American Society of Echocardiography(ASE)/American College of Cardiology (ACC)/American Heart Association(AHA) guidelines. The quantitative methods for assessment of MR severity via TTE involve the assessment of several independent data points as indicated in the ASE guidelines which includes flow convergence-based effective regurgitant orifice area (EROA) and regurgitant volume, pulse Doppler-based regurgitant volume, and the vena contracta. 4,11-14 Many assumptions underlie the assessment of MR by echocardiography, and hence, this assessment has limitations which arise from mitral regurgitation characteristics such as temporal change in orifice geometry, the possibility of multiple jets, the

“Circumnavigation”: A Worthy Descriptor to Depict Torrential Mitral Regurgitation and a Reverence to Ferdinand Magellan

“…Furthermore, we can assess SAM and flow acceleration across the LV outflow using the same sequence [ 4 ]. Using three-dimensional volume assessment and phase velocity mapping techniques, we can also assess the mitral regurgitant fraction with precision [ 5 ]. Using gadolinium, we can also assess myocardial fibrosis, which adds prognostic value [ 6 ].…”

“…All this information can help guide the management of the patient and can guide the surgeon if septal myectomy is planned. Perhaps, cardiac MRI’s unique attribute is its’ inherent ability to quantitate MR through non-geometric approaches, not reliant on proximal isovolumetric surface area, and to be more accurate than transthoracic or transesophageal echocardiogram, often leading to changes in patient care [ 5 , 7 ].…”

Is there a role for biomarkers in asymptomatic severe chronic primary mitral regurgitation?

“…CMR offers many advantages in the patient with chronic primary MR. CMR assesses volumetric flows and hence for more accurate, and reproducible measurements of MR severity, particularly when faced with eccentric MR which is often difficult to quantify with conventional echocardiography. Furthermore, CMR is considered the gold standard for the assessments of LV dimensions and LV function and can also provide accurate quantification of LA size and volume [43][44][45][46][47][48][49]. While there is a paucity of high-quality data on CMR based risk-stratification in patients with stage C1 disease, the ACC/AHA Guidelines, provides a Class 1 recommendation for CMR to assess LV and RV volumes and function and MR severity when there is a discrepancy between clinical assessments and echocardiography.…”

Rationale and clinical applications of 4D flow cardiovascular magnetic resonance in assessment of valvular heart disease: a comprehensive review

“…Quantification of mitral regurgitation, and therefore the indication for surgery or percutaneous intervention relies on TTE measurements in the majority of patients [ 1 , 3 ]. In selected cases, however, further investigation, including the use of CMR may be indicated [ 3 , 40 , 60 , 61 ]. CMR studies showed that PCMR reclassified a proportion of patients with mitral regurgitation into a different severity category, which in turn showed better association with prognosis.…”