New Perspective on Pathophysiology and Management of Functional Mitral Regurgitation

Atrial and ventricular functional mitral regurgitation: prevalence, characteristics, outcomes, and disease progression

AIMS

Limited data exist on the natural history of functional mitral regurgitation (FMR), including atrial (AFMR), ventricular (VFMR), and dual FMR. This study examined the prevalence, characteristics, outcomes, and progression of these FMR subtypes.

METHODS AND RESULTS

Consecutive patients with ≥mild to moderate FMR were included and classified as AFMR, VFMR, or dual FMR. AFMR is characterized by left atrial enlargement, while VFMR involves left ventricular enlargement or reduced left ventricular ejection fraction. Dual FMR combines features of both. Clinical outcome was all-cause mortality and heart failure (HF) hospitalization. Echocardiographic outcome was the progression from mild-moderate/moderate to severe FMR and from AFMR/VFMR to dual FMR. Of 22 814 patients, AFMR, VFMR, and dual FMR were identified in 39%, 14%, and 47%, respectively. Most (84%) had mild-moderate to moderate FMR. Over a median clinical follow-up of 4.7 years, dual FMR has the highest risk of all-cause mortality and HF hospitalization. Compared with AFMR, patients with VFMR have a higher incidence of all-cause mortality (adjusted HR = 1.73, 95%CI 1.54-1.94, P < 0.001) and HF hospitalization (adjusted HR = 1.23, 95%CI 1.15-1.32, P < 0.001). In the serial cohort with 2.4 (1.0-4.9) years echocardiogram follow-up, VFMR was associated with a 1.51-fold and 3.08-fold increase in the risk of progressing to severe FMR and dual FMR than AFMR (both P < 0.001). Sensitivity analyses did not change these findings.

CONCLUSION

AFMR and VFMR have significant differences in survival and disease progression. Dual FMR is a common and distinct disease process that occurs in the progression of AFMR or VFMR and is associated with a poor prognosis.

Single-cell analysis reveals the loss of FABP4-positive proliferating valvular endothelial cells relates to functional mitral regurgitation

BACKGROUND

Functional mitral regurgitation (MR) is a common form of mitral valve dysfunction that often persists even after surgical intervention, requiring reoperation in some cases. To advance our understanding of the pathogenesis of functional MR, it is crucial to characterize the cellular composition of the mitral valve leaflet and identify molecular changes in each cell subtype within the mitral valves of MR patients. Therefore, we aimed to comprehensively examine the cellular and molecular components of mitral valves in patients with MR.

METHODS

We conducted a single-cell RNA sequencing (scRNA-seq) analysis of mitral valve leaflets extracted from six patients who underwent heart transplantation. The cohort comprised three individuals with moderate-to-severe functional MR (MR group) and three non-diseased controls (NC group). Bioinformatics was applied to identify cell types, delineate cell functions, and explore cellular developmental trajectories and interactions. Key findings from the scRNA-seq analysis were validated using pathological staining to visualize key markers in the mitral valve leaflets. Additionally, in vitro experiments with human primary valvular endothelial cells were conducted to further support our results.

RESULTS

Our study revealed that valve interstitial cells are critical for adaptive valve remodelling, as they secrete extracellular matrix proteins and promote fibrosis. We discovered an abnormal decrease in a subpopulation of FABP4 (fatty acid binding protein 4)-positive proliferating valvular endothelial cells. The trajectory analysis identifies this subcluster as the origin of VECs. Immunohistochemistry on the expanded cohort showed a reduction of FABP4-positive VECs in patients with functional MR. Intervention experiments with primary cells indicated that FABP4 promotes proliferation and migration in mitral valve VECs and enhances TGFβ-induced differentiation.

CONCLUSIONS

Our study presented a comprehensive assessment of the mitral valve cellular landscape of patients with MR and sheds light on the molecular changes occurring in human mitral valves during functional MR. We found a notable reduction in the proliferating endothelial cell subpopulation of valve leaflets, and FABP4 was identified as one of their markers. Therefore, FABP4 positive VECs served as proliferating endothelial cells relates to functional mitral regurgitation. These VECs exhibited high proliferative and differentiative properties. Their reduction was associated with the occurrence of functional MR.

Efficacy of early administration of sacubitril/valsartan after coronary artery revascularization in patients with acute myocardial infarction complicated by moderate-to-severe mitral regurgitation: a randomized controlled trial

Effects of angiotensin receptor/neprilysin inhibitors (ARNI) on ventricular remodeling in patients with heart failure, especially heart failure with reduced ejection fraction (HFrEF), are better than those of angiotensin-converting enzyme inhibitors (ACEI). Acute myocardial infarction (AMI) complicated by mitral regurgitation exacerbates ventricular remodeling and increases the risk of heart failure. There is limited evidence on the effects of early administration of ARNI in patients with AMI complicated by mitral regurgitation. The aim of this trial was to examine the effectiveness and the safety of early administration of sacubitril/valsartan after coronary artery revascularization in patients with AMI complicated by moderate-to-severe mitral regurgitation. This was a randomized, single-blind, parallel-group, controlled trial. From June 2021 to June 2022, we enrolled 142 consecutive patients with AMI complicated by moderate-to-severe mitral regurgitation and followed them for 12 months. The patients received standard treatment for AMI and were randomly assigned to receive ARNI or benazepril. The primary efficacy end points were the differences in mitral regurgitant jet area (MRJA), mitral regurgitant volume (MRV), concentration of n-terminal pro-brain natriuretic peptide (NT-proBNP), left ventricular ejection fraction (LVEF), and left ventricular end-diastolic volume and end-systolic volume (LVEDV and LVESV) between groups and within groups at baseline, 1, 3, 6, and 12 months. Secondary end points included the rates of heart failure hospitalization, all-cause mortality, refractory angina, malignant arrhythmias, recurrent myocardial infarction, and stroke. Safety end points included the rates of hyperkalemia, renal dysfunction, hypotension, angioedema, and cough. The ARNI group had significantly lower NT-proBNP levels than the benazepril group at 1 month and later (P < 0.001). MRJA and MRV significantly improved in the ARNI group compared with the benazepril group at 12 months (MRJA: - 3.21 ± 2.18 cm2 vs. - 1.83 ± 2.81 cm2, P < 0.05; MRV: - 27.22 ± 15.22 mL vs. - 13.67 ± 21.02 mL, P < 0.001). The ARNI group also showed significant reductions in LVEDV and LVESV (P < 0.05) and improvement in LVEF (P < 0.05). Secondary end point analysis showed a significantly higher rate of heart failure hospitalization in the benazepril group compared with the ARNI group (HR = 2.03, 95% CI 1.12-3.68, P = 0.021). Safety end point analysis showed a higher rate of hypotension in the ARNI group (P < 0.05). Early use of sacubitril/valsartan after coronary artery revascularization in patients with AMI complicated by moderate-to-severe mitral regurgitation can significantly reduce mitral regurgitation, improve ventricular remodeling, and decrease heart failure hospitalization. Nevertheless, caution is needed to avoid hypotension. Chinese Clinical Trial Registry (ChiCTR2100054255) registered on December 11, 2021.

Aortic Regurgitation: Review of Current Management

ABSTRACT

Aortic regurgitation (AR) is a valvular disease characterized by retrograde blood flow from the aorta to the left ventricle. Various etiologies result in either an acute or chronic clinical presentation of AR and affect the severity of disease progression. Acute AR is a medical emergency caused by sudden increases in left ventricular volume. Immediate surgical intervention, vasoactive agents, and antibiotics are crucial for management. Chronic AR progresses gradually, leading to heart failure symptoms due to left ventricular remodeling. Diagnoses of both acute and chronic AR rely on electrocardiography, chest radiographs, and echocardiography. Cardiac magnetic resonance imaging may be incorporated in chronic AR diagnosis. Medical management of chronic AR aims to control hypertension and delay left ventricular dysfunction. Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and potentially calcium-channel blockers are recommended for chronic AR. β-Blockers are cautioned against because of their potential negative effects. This article emphasizes the importance of early diagnosis and prompt surgical intervention in AR. This review provides a comprehensive overview of the pathophysiology and clinical manifestations of acute and chronic AR and a medication regimen for treating chronic AR in the adult population.

Bileaflet Tethering With Preserved LV Geometry and Function: An Unusual Mechanism of Functional Mitral Regurgitation

An 81-year-old woman presented with acute pulmonary edema. Echocardiography revealed severe functional mitral regurgitation, the mechanism of which was unusual. An atypical bileaflet tethering caused by disharmonic annular remodeling, concomitant aortic dilatation, and reduced aorto-mitral angle without left ventricular dysfunction or dilatation was found. A transcatheter edge-to-edge repair was nonetheless successfully performed.

Left ventricular reverse remodeling after transcatheter aortic valve replacement for predominant aortic stenosis and mixed aortic valve disease

BACKGROUND

Mixed aortic valve disease (MAVD) is a frequent concomitant valve disease with unique cardiac pathological changes compared to predominant aortic stenosis (PAS). The previous studies about the MAVD are contradictory. Therefore, a new perspective is needed to assess the value of TAVR for this cohort of patients.

METHODS

From January 2018 to December 2021, 90 MAVD patients and 72 PAS patients who underwent TAVR in our hospital were collected. 1:1 propensity score matching analysis was used to control the bias in patient selection. The dynamic changes in left ventricular morphology and hemodynamics were compared by generalized estimating equations. Univariate or multivariate logistic regression analysis was used to screen for independent risk factors for the non-occurrence of left ventricular reverse remodeling (non-LVRR).

RESULTS

After the matching procedure, 112 patients were included in the analysis (56 in each group). Baseline characteristics were similar between the two groups. LVRR occurred in both groups, but MAVD had greater left ventricular end-diastolic volume index and left ventricular mass index, a higher incidence of mitral regurgitation (MR), and a more pronounced transformation of ventricular geometry patterns. Post-operative MR (odd ratio [OR]: 10.05; 95% confidence interval [CI]: 2.08-48.57; p < .001) and coronary artery disease (OR: 2.82; 95% CI: 1.08-7.34; p = .034) were independent risk factors for non-LVRR.

CONCLUSION

LVRR also occurs in patients with MAVD, post-operative MR and coronary artery disease were independent risk factors for non-LVRR.