A Comparative Assessment of Echocardiographic Parameters for Determining Primary Mitral Regurgitation Severity Using Magnetic Resonance Imaging as a Reference Standard

Mitral Regurgitation: Advanced Imaging Parameters and Changing Treatment Landscape

Mitral regurgitation is a common valvular heart disease with increasing prevalence due to the aging population. In degenerative (primary) mitral regurgitation, medical therapies are limited and the mainstay of treatment is mitral valve surgery. Patients are referred for mitral valve surgery based on the American College of Cardiology/American Heart Association guidelines, which recommend surgery in patients with severe mitral regurgitation. Echocardiography uses multiple parameters that lack reproducibility and accuracy. Studies comparing cardiovascular magnetic resonance (CMR) and echocardiography have shown that CMR is a better predictor of clinical outcome and postsurgical left ventricular remodeling than echocardiography.

The relationship between mitral regurgitant severity, symptoms, and exercise capacity in primary degenerative mitral regurgitation

Although it is assumed that more severe MR is associated with a greater burden of symptoms and lower exercise capacity, the relationship between symptoms, exercise capacity, and mitral regurgitant severity has not been well studied. We prospectively studied 67 (63 ± 11 years, 72% male) patients with at least mild degenerative MR and left ventricular ejection fraction ≥ 50% who underwent stress echocardiography, CMR, and evaluation with the Kansas City Cardiomyopathy questionnaire (KCCQ). Symptoms and exercise capacity were evaluated in the context of MR severity. Patients reporting dyspnea had lower KCCQ symptom scores (79 ± 23 vs. 96 ± 9, p = 0.01) and achieved lower percentage of age and gender predicted METs (114 ± 37 vs. 152 ± 43%, p < 0.001) compared to those without dyspnea. There was no significant difference in MR volume between those with vs. without dyspnea by CMR (43 ± 26 ml vs. 51 ± 28 ml, p = 0.3) or echocardiography (64 ± 28 vs. 73 ± 41ml, p = 0.4). Those with severe MR by CMR had similar KCCQ symptom scores (96 ± 10 vs. 89 ± 17, p = 0.04) and percentage of age and gender predicted METs (148 ± 42 vs. 133 ± 47%, p = 0.2) to those without severe MR. Those with severe MR by echocardiography had similar KCCQ symptom score (93 ± 15 vs. 89 ± 16, p = 0.3) and percentage of age and gender predicted METs (138 ± 43 vs. 153 ± 46%, p = 0.2) to those without severe MR. Patients with degenerative MR assessed by CMR and stress echocardiography, there was no relationship between MR severity and either symptoms or exercise capacity. These findings highlight the disconnect between symptoms and the severity of MR and challenge the assumption that correcting MR can be counted on to improve symptom status in patients with degenerative MR.

Quantification of primary mitral regurgitation by echocardiography: A practical appraisal

The accurate quantification of primary mitral regurgitation (MR) and its consequences on cardiac remodeling is of paramount importance to determine the best timing for surgery in these patients. The recommended echocardiographic grading of primary MR severity relies on an integrated multiparametric approach. It is expected that the large number of echocardiographic parameters collected would offer the possibility to check the measured values regarding their congruence in order to conclude reliably on MR severity. However, the use of multiple parameters to grade MR can result in potential discrepancies between one or more of them. Importantly, many factors beyond MR severity impact the values obtained for these parameters including technical settings, anatomic and hemodynamic considerations, patient's characteristics and echocardiographer' skills. Hence, clinicians involved in valvular diseases should be well aware of the respective strengths and pitfalls of each of MR grading methods by echocardiography. Recent literature highlighted the need for a reappraisal of the severity of primary MR from a hemodynamic perspective. The estimation of MR regurgitation fraction by indirect quantitative methods, whenever possible, should be central when grading the severity of these patients. The assessment of the MR effective regurgitant orifice area by the proximal flow convergence method should be used in a semi-quantitative manner. Furthermore, it is crucial to acknowledge specific clinical situations in MR at risk of misevaluation when grading severity such as late-systolic MR, bi-leaflet prolapse with multiple jets or extensive leak, wall-constrained eccentric jet or in older patients with complex MR mechanism. Finally, it is debatable whether the 4-grades classification of MR severity would be still relevant nowadays, since the indication for mitral valve (MV) surgery is discussed in clinical practice for patients with 3+ and 4+ primary MR based on symptoms, specific markers of adverse outcome and MV repair probability. Primary MR grading should be seen as a continuum integrating both quantification of MR and its consequences, even for patients with presumed “moderate” MR.

The Role of Cardiovascular Magnetic Resonance in Patients with Mitral Regurgitation

The 2019 Global Burden of Disease (GBD) study estimated that there were approximately 24.2 million people affected worldwide by degenerative mitral regurgitation (MR), resulting in 34,200 deaths. After aortic stenosis, MR is the most prevalent VHD in Europe and the second-most common VHD to pose indications for surgery in western countries. Current ESC and AHA/ACC guidelines for the management of VHD emphasize the importance of an integrative approach for the assessment of MR severity, which is of paramount importance in dictating the timing for surgery. Transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) are the first-line imaging modalities; however, despite the technological advancement, sometimes, the final diagnosis on the degree of the disease may still be challenging. In the last 20 years, CMR has emerged as a robust technique in the assessment of patients with cardiac disease, and, recently, its role is gaining more and more importance in the field of VHD. In fact, CMR is the gold standard in the assessment of cardiac volumes, and it is possible to accurately evaluate the regurgitant volume. The purpose of this review is to outline the current state-of-the-art management of MR by using Cardiac Magnetic Resonance (CMR).

American Society of Echocardiography Algorithm for Degenerative Mitral Regurgitation: Comparison With CMR

OBJECTIVES

The purpose of this study was to compare the American Society of Echocardiography (ASE) algorithm for assessing mitral regurgitation (MR) to cardiac magnetic resonance (CMR) and left ventricular (LV) remodeling following mitral intervention.

BACKGROUND

The ASE recommends integrating multiple echocardiographic parameters for assessing MR. The ASE guidelines include an algorithm that weighs the parameters and highlights those considered indicative of definitely mild or definitely severe MR.

METHODS

We prospectively enrolled 152 (age 62 ± 13 years; 59% male) patients with degenerative MR who underwent ASE algorithm-guided echocardiographic and CMR grading of MR severity. Using the ASE algorithm, patients were graded as definitely mild, grade I, grade II, grade III, grade IV, or definitely severe MR. CMR MR volume was graded as mild (<30 mL), grade II moderate (30-44 mL), grade III moderate (45-59 mL), or severe (≥60 mL). A subgroup of 63 patients underwent successful mitral intervention, of whom 48 had postintervention CMR.

RESULTS

Only 52% of patients with definitely severe MR by the ASE algorithm had severe MR by CMR, and 10% had mild MR by CMR. There was an increase in post mitral intervention LV reverse remodeling with worsening MR severity using CMR (P < 0.0001) but not the ASE algorithm (P = 0.07). Severe MR by CMR was an independent predictor of post mitral intervention LV reverse remodeling and definitely severe MR by the ASE algorithm was not.

CONCLUSIONS

In patients with degenerative MR, agreement between CMR and the ASE algorithm was suboptimal. Severe MR by CMR was an independent predictor of post mitral intervention LV reverse remodeling, whereas definitely severe MR by the ASE algorithm was not. These findings suggest an important role for CMR in surgical decision making in degenerative MR. (Comparison Study of Echocardiography and Cardiovascular Magnetic Resonance Imaging in the Assessment of Mitral and Aortic Regurgitation; NCT04038879).

Characterization of Primary Mitral Regurgitation With Flail Leaflet and/or Wall-Impinging Flow

BACKGROUND

Echocardiography guidelines note that a flail leaflet is a specific criterion for severe mitral regurgitation (MR) and that regurgitant severity is underestimated in wall-impinging jets (Coandă effect). Both findings are often considered to be pathognomonic of severe MR.

OBJECTIVES

In this study, the authors sought to determine the association of flail leaflet and Coandă effect with MR severity quantified by means of cardiac magnetic resonance (CMR).

METHODS

The authors enrolled 158 consecutive patients with primary MR according to echocardiography and CMR. The presence of a flail leaflet or Coandă was determined for each patient. CMR regurgitant volume (RV) and regurgitant fraction (RF) were quantified for all patients.

RESULTS

There were 55 patients (35%) with a flail leaflet, 52 (33%) with Coandă, and 22 (14%) with a flail leaflet and Coandă. The mean CMR mitral RV and RF progressively increased in patients without a Coandă or flail, a Coandă, a flail, or a Coandă and a flail (RV: 28 ± 21 mL vs 43 ± 23 mL vs 58 ± 29 mL vs 64 ± 25 mL [P < 0.001]; RF: 25% ± 16% vs 34% ± 14% vs 41% ± 12% vs 45% ± 12% [P < 0.001]). With the use of CMR RV, 35%, 46%, and 59% of patients had severe MR with the presence of a Coandă, flail leaflet, or both, respectively. With the use of CMR RF, 25%, 31%, and 40% of patients had severe MR with the presence of a Coandă, flail leaflet, or both, respectively.

CONCLUSIONS

While the presence of a flail leaflet and Coandă effect on echocardiography are associated with higher regurgitant volumes and fractions, they are frequently not associated with severe MR as assessed by means of CMR. (Comparison Study of Echocardiography and Cardiovascular Magnetic Resonance Imaging in the Assessment of Mitral and Aortic Regurgitation; NCT04038879).

Mitral regurgitation and dyspnoea: the expanding role of mitral effective regurgitant orifice among un-selected patients

AIMS

Mitral regurgitation is frequent in the general population and among suspected heart failure patients; however, to what extent it contributes to dyspnoea is unclear. We hypothesized mitral regurgitation to have a role in determining dyspnoea in unselected ambulatory patients.

METHODS

Consecutive outpatients referred for echocardiography were retrospectively screened and included. We excluded patients with mitral stenosis or prosthesis, congenital heart disease, cardiac surgery (previous 6 months) and atrial fibrillation. Patients were classified into four dyspnoea grades based on how they perceived their disability. We assessed mitral regurgitation severity through the effective regurgitant orifice area (ERO).

RESULTS

One hundred and fifty-four patients (58% men; age 67 ± 14 years; mean ejection fraction 54 ± 12%) formed the study population; 76 (49%) classified asymptomatic (grade I), 63 (41%) dyspnoea grade II and 15 (10%) grade III; none was in grade IV. Mitral regurgitation was present in 102 patients (66%): primary in 14 (14%) and secondary in 88 (86%); among grades I, II and III patients, mitral regurgitation was present in 35 (46%; ERO 0.05 ± 0.10 cm), 52 (82%; ERO 0.10 ± 0.13 cm) and 15 (100%; ERO 0.20 ± 0.11 cm) patients, respectively (P < 0.0001). After adjusting for clinical (age, hypertension, ischemic heart disease, chronic kidney injury, chronic pulmonary disease) and echocardiographic confounders (ejection fraction, E/e'), ERO remained associated with symptoms presence (grade I versus II - III; P = 0.01 and P = 0.03, respectively).

CONCLUSION

Among unselected heterogeneous ambulatory patients, mitral ERO was associated with the presence of dyspnoea and could therefore help in identifying symptomatic patients and in clinical characterization of patients with perceived dyspnoea.

Concordance and Discordance of Echocardiographic Parameters Recommended for Assessing the Severity of Mitral Regurgitation

BACKGROUND

The American College of Cardiology/American Heart Association and American Society of Echocardiography guidelines recommend assessing several echocardiographic parameters when evaluating mitral regurgitation (MR) severity. These parameters can be discordant, making the assessment of MR challenging. The degree to which echocardiographic parameters of MR severity are concordant is not well studied.

METHODS

We enrolled 159 patients in a prospective multicenter study. Eight parameters were included in this analysis: proximal isovelocity surface area (PISA)-derived regurgitant volume, PISA-derived effective regurgitant orifice area, vena contracta, color Doppler jet/left atrial area, left atrial volume index, left ventricular end-diastolic volume index, peak E wave, and the presence of pulmonary vein systolic reversal. Each echocardiographic parameter was determined to represent severe or nonsevere MR according to the American Society of Echocardiography guidelines. A concordance score was calculated as [Formula: see text] so that a higher score reflects greater concordance. There was no discordance when all the echocardiographic parameters agreed and high discordance when 3 or 4 parameters were discordant.

RESULTS

The mean concordance score was 75±14% for the entire cohort. There were 9 (6%) patients with complete agreement of all parameters and 61 (38%) with high discordance. There was greater discordance in patients with severe MR but no difference between primary versus secondary or central versus eccentric jets. There was an improvement in concordance when only considering PISA-based regurgitant volume, PISA-based effective regurgitant orifice area, and vena contracta with agreement in 68% of patients.

CONCLUSIONS

There was limited concordance between the echocardiographic parameters of MR severity, and the discordance was worse with more severe MR. Concordance improved when considering only 3 quantitative measures of vena contracta and PISA-based effective regurgitant orifice area and regurgitant volume. These findings highlight the challenges facing echocardiographers when assessing the severity of MR and emphasize the difficulty of using an integrated approach that incorporates multiple components. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04038879.

[Evaluation of mitral regurgitation : How much quantification do we need?]

Severe mitral regurgitation (MR) is associated with increased morbidity and mortality. Thus, the correct evaluation of the underlying etiology, pathomechanism and severity is crucial for optimal treatment. Echocardiography is the predominant diagnostic modality in the clinical routine as it enables grading of mitral regurgitation, which can frequently be achieved by readily available qualitative parameters. Additionally, echocardiography provides several methods to quantify the hemodynamic significance of MR. The effective regurgitation orifice area (EROA) is the quantitative parameter best correlated with clinical events. American and European imaging guidelines both recommend the use of quantitative parameters even though they disagree on the cut-off values for secondary MR. The evaluation of MR should always include an assessment of the adjacent heart chambers in order to be able to assess the impact of volume overload on size and function of the left ventricle and left atrium. The final interpretation of the quantitative parameters requires knowledge of left ventricular volume and ejection fraction. Newer 3D-echocardiographic approaches to quantify MR are less dependent on mathematical assumptions and have shown convincing results in several studies but still lack sufficient clinical validation. As an alternative to echocardiography, for specific indications cardiac magnetic resonance imaging (MRI) has proven to be a systematic and observer-independent method for quantification of MR.

The Average Pixel Intensity Method and Outcome of Mitral Regurgitation in Mitral Valve Prolapse

BACKGROUND

Mitral regurgitation (MR) is a frequent consequence of mitral valve prolapse (MVP). However, the echocardiographic grading of MR is challenging, and the recommended grading parameters have several limitations. The authors developed a novel echocardiographic parameter to grade MR, the average pixel intensity (API) method, on the basis of pixel intensity analysis of the continuous-wave Doppler signal.

METHODS

Transthoracic echocardiography was performed prospectively in consecutive patients with MVP (N = 149). MR was quantitatively assessed using the API method, vena contracta width, effective regurgitant orifice area, and regurgitant volume. The primary clinical events were cardiovascular mortality, mitral valve surgery, percutaneous mitral intervention, and heart failure hospitalization.

RESULTS

The API method was feasible in 90% of all patients with MVP, which was significantly higher than vena contracta width, effective regurgitant orifice area, and regurgitant volume. During a median follow-up period of 17 months, 44 patients (32%) had major adverse cardiac events, and the majority of events occurred in the holosystolic MVP subgroup. The degree of MR severity by the API method was highly significant for the prediction of events. An API cutoff of 111 arbitrary units was defined as "severe" MR due to MVP, with overall superior sensitivity and specificity compared with cutoffs for established MR grading parameters. In patients who did not have major adverse cardiac events during the follow-up period (n = 92), no significant changes in measures of MR severity were found on follow-up echocardiography.

CONCLUSIONS

The API method is predictive of clinical events and outcomes in MR due to MVP. Therefore, the API method may be considered for grading the severity of MR due to MVP in clinical practice.

Impact of Mitral Regurgitation Severity and Cause on Effort Tolerance-Integrated Stress Myocardial Perfusion Imaging and Echocardiographic Assessment of Patients With Known or Suspected Coronary Artery Disease Undergoing Exercise Treadmill Testing

Background Mitral regurgitation ( MR ) has the potential to impede exercise capacity; it is uncertain whether this is because of regurgitation itself or the underlying cause of valvular insufficiency. Methods and Results The population comprised 3267 patients who underwent exercise treadmill myocardial perfusion imaging and transthoracic echocardiography within 6±8 days. MR was present in 28%, including 176 patients (5%) with moderate or greater MR . Left ventricular systolic function significantly decreased and chamber size increased in relation to MR , paralleling increments in stress and rest myocardial perfusion deficits (all P<0.001). Exercise tolerance (metabolic equivalents of task) decreased stepwise in relation to graded MR severity ( P<0.05). Workload was significantly lower with mild versus no MR (mean±SD, 9.8±3.0 versus 10.1±3.0; P=0.02); magnitude of workload reduction significantly increased among patients with advanced versus those with mild MR (mean±SD, 8.6±3.0 versus 9.8±3.0; P<0.001). MR -associated exercise impairment was accompanied by lower heart rate and blood pressure augmentation and greater dyspnea (all P<0.05). Both functional and nonfunctional MR subgroups demonstrated significantly decreased effort tolerance in relation to MR severity ( P≤0.01); impairment was greater with functional MR ( P=0.04) corresponding to more advanced left ventricular dysfunction and dilation (both P<0.001). Functional MR predicted reduced metabolic equivalent of task-based effort (B=-0.39 [95% CI, -0.62 to -0.17]; P=0.001) independent of MR severity. Among the overall cohort, advanced (moderate or greater) MR was associated with reduced effort tolerance (B=-1.36 [95% CI, -1.80 to -0.93]; P<0.001) and remained significant ( P=0.01) after controlling for age, clinical indexes, stress perfusion defects, and left ventricular dysfunction. Conclusions MR impairs exercise tolerance independent of left ventricular ischemia, dysfunction, and clinical indexes. Magnitude of exercise impairment parallels severity of MR .