Mechanisms of functional mitral regurgitation in ischemic cardiomyopathy determined by transesophageal echocardiography (from the Surgical Treatment for Ischemic Heart Failure Trial)

The role of surgery for secondary mitral regurgitation and heart failure in the era of transcatheter mitral valve therapies

The approach to the management of mitral valve (MV) disease and heart failure (HF) has dramatically changed over the last decades. It is well recognized that severe mitral regurgitation secondary to ischemic or non-ischemic cardiomyopathy is associated with an excess risk of mortality. Understanding the impact of the surgical treatment modality on mortality outcomes has been difficult due to the broad spectrum of secondary mitral regurgitation (SMR) phenotypes and lack of randomized surgical clinical trials. Over the last 30 years, surgeons have failed to provide compelling evidence to convince the medical community of the need to treat SMR in patients with severe HF. Therefore, the surgical treatment of SMR has never gained uniform acceptance as a significant option among patients suffering from SMR. Recent evidence from randomized trials in a non-surgical eligible patients treated with transcatheter therapies, has provided a new perspective on SMR treatment. Recently published European and American guidelines confirm the key role of percutaneous treatment of SMR and in parallel, these guidelines reinforce the role of mitral valve surgery in patients who require surgical revascularization. Complex mitral valve repair combining subvalvular apparatus repair along with annuloplasty seems to be a promising approach in selected patients in selected centers. Meanwhile, mitral valve replacement has become the preferred surgical strategy in most patients with advanced heart failure and severe LV remodeling or high risk of recurrent mitral regurgitation. In this comprehensive review, we aimed to discuss the role of mitral surgery for SMR in patients with heart failure in the contemporary era and to provide a practical approach for its surgical management.

Translocation of the Mitral Valve in an Acute Large Animal Model

Current repair options for functional mitral regurgitation (FMR) are not durable and do not adequately address underlying pathophysiology including leaflet tethering and insufficient coaptation. The feasibility of mitral valve translocation as a repair strategy for FMR was examined in normal swine. Seven pigs (median 62 kg, IQR 55-65 kg) with normal cardiac function were implanted with a 1-cm frustum-shaped pericardial patch inserted between the native mitral annulus and intact mitral leaflets. Operative survival was 100% with no post-procedure mitral stenosis, systolic anterior motion, or central mitral regurgitation observed on echocardiography. Post-translocation mean gradient was 3.5 mmHg (IQR 1.5-4 mmHg); trace or mild suture line leaks on the atrial suture line were noted in 5/7 pigs. Median leaflet coaptation increased from 2.4 (IQR 2.1-4.3 mm) to 12.4 mm (IQR 10.8-13.4 mm) after translocation (P = 0.016). Translocation dramatically increases leaflet coaptation without impairing diastolic function in animals with normal left ventricular function and is a promising technique for repair of FMR. Implantation of a 1.0-cm circumferential pericardial patch (mitral valve translocation) increases leaflet coaptation in a normal animal model.

Echocardiographic Advances in Dilated Cardiomyopathy

Although the overall survival of patients with dilated cardiomyopathy (DCM) has improved significantly in the last decades, a non-negligible proportion of DCM patients still shows an unfavorable prognosis. DCM patients not only need imaging techniques that are effective in diagnosis, but also suitable for long-term follow-up with frequent re-evaluations. The exponential growth of echocardiography’s technology and performance in recent years has resulted in improved diagnostic accuracy, stratification, management and follow-up of patients with DCM. This review summarizes some new developments in echocardiography and their promising applications in DCM. Although nowadays cardiac magnetic resonance (CMR) remains the gold standard technique in DCM, the echocardiographic advances and novelties proposed in the manuscript, if properly integrated into clinical practice, could bring echocardiography closer to CMR in terms of accuracy and may certify ultrasound as the technique of choice in the follow-up of DCM patients. The application in DCM patients of novel echocardiographic techniques represents an interesting emergent research area for scholars in the near future.

Mitral Valve Translocation: Optimization of Patch Geometry in an Ex Vivo Model of Secondary Mitral Regurgitation

Optimal translocation patch width for functional mitral regurgitation (FMR) treatment was evaluated in an air-filled ex vivo system. FMR was created in 19 isolated swine hearts by annular dilation and papillary muscle displacement. Frustum-shaped pericardial patches of varying widths (Group 1 = 0.5 cm; Group 2 = 1.0 cm; Group 3 = 1.5 cm) were implanted and imaged via a 3D-structured light scanner. Median leaflet coaptation decreased (P < 0.001) from 5.5 ± 2.0 mm at baseline to 2.4 ± 1.3 mm following FMR creation. Translocation repair increased coaptation length over FMR levels by 2.2 mm in Group 1 (P < 0.001), 4.6 mm in Group 2 (P < 0.001), and 4.7 mm in Group 3 (P < 0.001). After repair, no significant differences were found between groups for annular height, circularity index, tenting height, tenting area, and non-coapting surface area. The supranormal coaptation and minimal valve geometric changes support using a 1.0- or 1.5-cm translocation patch for FMR treatment. Implantation of a 1.0-cm or 1.5-cm circumferential pericardial patch (mitral valve translocation) increases leaflet coaptation length without significantly altering valve geometry.

Profile and early outcomes of surgical reconstruction of coronary artery atresia in children

OBJECTIVES

Coronary artery atresia is a rare coronary artery anomaly in children and has a high rate of misdiagnosis. We aimed to summarize the profile and early outcomes after the surgical reconstruction of coronary artery atresia in children.

METHODS

A retrospective analysis was performed in 12 consecutive patients with coronary artery atresia who were admitted to the Department of Paediatric Cardiac Surgery of Fuwai Hospital between October 2016 and September 2020. Ten patients underwent surgical reconstruction of the coronary artery with the pulmonary artery anterior wall, and 8 patients underwent concomitant mitral valvuloplasty.

RESULTS

There were 6 females and 6 males, with an age of 1.75 years [interquartile range (IQR), 1.0-3.5] and weight of 10.0 kg (IQR, 8.9-14.75). There were 10 cases of left coronary artery atresia and 2 cases of right coronary artery atresia. All the patients were initially misdiagnosed in the outpatient clinic, but further nonselective coronary angiography confirmed the diagnosis of coronary artery atresia. In all 10 patients with mitral regurgitation, echocardiogram of the mitral valve chordae and papillary muscle revealed ischaemic changes. The clamp time was 89.0 min (IQR, 75.0-101.0), the pump time was 126.0 min (IQR, 119.0-132.0) and the intensive care unit stay time was 1.5 days (IQR, 1.0-3.0). No perioperative deaths were noted. After 9.5 months (IQR, 5.5-13.5) of follow-up, 2 patients with fractional shortening that significantly decreased to 14.1% and 14.8% died and 1 patient had moderate pericardial effusion that improved after treatment with oral diuretics. Coronary artery ultrasound and enhanced computed tomography showed a patent main coronary artery in all the patients.

CONCLUSIONS

Coronary artery atresia in children is often associated with mitral regurgitation, and mitral valve chordae and papillary muscle exhibit ischaemic changes. Coronary artery reconstruction is safe and effective in children with coronary artery atresia.

Initial Clinical Experience With Mitral Valve Translocation for Secondary Mitral Regurgitation

BACKGROUND

Functional (secondary) mitral regurgitation (FMR) results from altered geometry of the mitral valve apparatus. Repair with restrictive mitral annuloplasty is associated with high rates of recurrent mitral regurgitation (MR). We developed a novel operative repair for FMR that translocates the intact mitral valve towards the apex.

METHODS

The mitral valve was detached circumferentially and translocated into the ventricle with a frustum-shaped glutaraldehyde-treated autologous pericardial patch. Clinical and echocardiographic follow-up was performed.

RESULTS

Fifteen consecutive patients with FMR (mean age, 59 years; 67% female) had mitral valve translocation between 2018 and 2020. Preoperative mean ejection fraction, left ventricular end-diastolic dimension, and systolic pulmonary artery pressure were 40% ± 11%, 59 ± 8 mm, and 49 ± 21 mm Hg, respectively; 33% had atrial fibrillation. Cardiomyopathy was ischemic in 4 and nonischemic in 11. Concomitant procedures included tricuspid valve operation (n = 8), coronary artery bypass grafting (n = 4), and atrial fibrillation ablation (n = 5). Post bypass transesophageal echocardiogram demonstrated none/trace MR in all patients and mean gradient of 3 mm Hg (interquartile range, 2-4 mm Hg). Mean leaflet extent of coaptation was 14 ± 2 mm (range, 11-17 mm). There was no postoperative mortality, stroke, or renal failure. Predismissal echocardiography showed none/trace MR in 14 patients and mild MR in 1. One patient underwent successful late rerepair of a suture line leak. Twelve patients were alive at latest follow-up and MR at 1 and 6 months was mild or less in all patients with mean leaflet extent of coaptation of 14 ± 2 mm (range, 12-16 mm) at 6 months.

CONCLUSIONS

Mitral valve translocation creates a large surface of coaptation and effectively corrects FMR. Further study is needed to demonstrate the long-term durability and clinical utility of this operation.

Disproportionate secondary mitral regurgitation: myths, misconceptions and clinical implications

Secondary (functional) mitral regurgitation (SMR) most commonly arises secondary to left ventricular (LV) dilation/dysfunction. The concept of disproportionately severe SMR was proposed to help explain the different results of two randomised trials of transcatheter edge-to-edge mitral valve repair (TEER) versus medical therapy. This concept is based on the fact that effective regurgitant orifice area (EROA) depends on LV end-diastolic volume (LVEDV), ejection fraction, regurgitant fraction and the velocity-time integral of SMR. This review focuses on the haemodynamic framework underlying the concept and the myths and misconceptions arising from it. Each component of EROA/LVEDV is prone to measurement error which can result in misclassification of individual patients. Moreover, EROA is typically measured at peak systole rather than its mean value over the duration of MR. This can result in physiologically impossible values of EROA or regurgitant volume. Although the EROA/LVEDV ratio (1) emphasises that grading MR severity needs to consider LV size and function and (2) helps explain the different outcomes between COAPT and MITRAFR, there are important factors that are not included. Among these are left atrial compliance, LV pressure and ejection fraction, pulmonary hypertension, right ventricular function and tricuspid regurgitation. Because medical therapy can reduce LV volumes and improve both LV function and SMR severity, the key to patient selection is forced titration of neurohormonal antagonists to the target doses that have been proven in clinical trials (along with cardiac resynchronisation when appropriate). Patients who continue to have symptomatic severe SMR after doing so should be considered for TEER.

Minimally invasive mitral valve repair for functional mitral regurgitation

Systolic heart failure is frequently accompanied by a relevant functional mitral valve regurgitation (FMR) which develops as a direct sequela of the ongoing left ventricular remodelling. The severity of mitral regurgitation is further aggravated by progressive left ventricular enlargement causing leaflet tethering and reduced systolic leaflet movement. The prognosis of such patients is obviously limited by an underlying left ventricular disease, and the correction of secondary FMR has been previously suggested as predominantly ‘cosmetic’ surgery in the setting of ongoing cardiomyopathy. Inferior results of an isolated annuloplasty in type IIIb FMR supported the philosophy of malignant course of progressive cardiomyopathy and resulted in increasingly restricted indications for mitral valve surgery for FMR in the guidelines. The lack of a standardized pathophysiological approach to correct type IIIb FMR led to the development of valve replacement strategy and edge-to-edge catheter-based mitral valve procedures, which became the most frequent procedures in the FMR setting in Europe. Modern mitral valve surgery combines the advantages of 3-dimensional endoscopic minimally invasive surgical approach with standardized subannular repair to address the pathophysiological background of type IIIb FMR. The perioperative results have been significantly improved, and there is a growing evidence of improved long-term stability of subannular repair procedures as compared to isolated annuloplasty. This review article aims to present the current state-of-the-art of the modern mitral valve surgery in FMR and provides suggestions for future trials analysing the potential advantages in these patients.

Contrasting Effects of Pharmacological, Procedural, and Surgical Interventions on Proportionate and Disproportionate Functional Mitral Regurgitation in Chronic Heart Failure

Two distinct pathways can lead to functional mitral regurgitation (MR) in patients with chronic heart failure and a reduced ejection fraction. When remodeling and enlargement of the left ventricle (LV) cause annular dilatation and tethering of the mitral valve leaflets, there is a linear relationship between LV end-diastolic volume and the effective regurgitant orifice area of the mitral valve. These patients, designated as having proportionate MR, respond favorably to treatments that lead to reversal of LV remodeling and a decrease in LV volumes (eg, neurohormonal antagonists and LV assist devices), but they may not benefit from interventions that are directed only at the mitral valve leaflets (eg, transcatheter mitral valve repair). In contrast, when ventricular dyssynchrony causes functional MR attributable to unequal contraction of the papillary muscles, the magnitude of regurgitation is greater than that predicted by LV volumes. These patients, designated as having severe but disproportionate MR, respond favorably to treatments that are directed to the mitral valve leaflets or their supporting structures (eg, cardiac resynchronization or transcatheter mitral valve repair), but they may derive little benefit from interventions that act only to reduce LV cavity size (eg, pharmacological treatments). This novel conceptual framework reflects the important interplay between LV geometry and mitral valve function in determining the clinical presentation of patients, and it allows characterization of the determinants of functional MR to guide the most appropriate therapy in the clinical setting.

Characterization of 3-dimensional papillary muscle displacement in in vivo ovine models of ischemic/functional mitral regurgitation

OBJECTIVE

Papillary muscle (PM) displacement contributes to ischemic/functional mitral regurgitation (IMR/FMR). The displaced PMs pull the mitral leaflets into the left ventricle (ie, toward the apex) thus hampering leaflet coaptation. Intuitively apical leaflet tethering results from apical PM displacement. The 3-dimensional directions of PM displacement are, however, incompletely characterized.

METHODS

Data from in vivo ovine models of IMR (6-8 weeks of posterolateral infarction, n = 12) and FMR (9-21 days of rapid left ventricular pacing, n = 11) were analyzed. All sheep had radiopaque markers implanted on the anterior and posterior PM (PPM) tips, around the mitral annulus, and on the left ventricular apex. To explore 3-dimensional PM displacement directions, differences in marker coordinates were calculated at end-systole before and during IMR/FMR using a right-handed coordinate system centered on the mitral annular "saddle horn" with the y-axis passing through the apical marker.

RESULTS

No apical PM displacement was observed during either IMR or FMR. The anterior PM displaced laterally during FMR. Posterolateral PPM displacement was observed during IMR and FMR.

CONCLUSIONS

Experimental in vivo ovine models suggest posterolateral PPM displacement as a predominant pathomechanism leading to apical leaflet tethering during IMR/FMR.

Identification and Quantification of Degenerative and Functional Mitral Regurgitation for Patient Selection for Transcatheter Mitral Valve Repair

Chronic mitral regurgitation (MR), whether due to valve degeneration or secondary to myocardial disease, affects an increasing proportion of the aging population. Percutaneous mitral valve interventions, including edge-to-edge repair, are emerging as feasible and effective therapy for patients with severe MR at high or prohibitive surgical risk. Imaging with echocardiography is crucial for patient selection by evaluating mitral anatomy, the mechanism of dysfunction, and MR severity. In this article, the authors review the imaging characteristics for identifying and quantifying degenerative and functional MR for transcatheter mitral valve repair.

Assessment of the severity of native mitral valve regurgitation

Mitral regurgitation (MR) is a major cause of cardiovascular morbidity and mortality. MR is classified as primary (organic) if it is due to an intrinsic valve abnormality, or secondary (functional) if the etiology is because of remodeling of left ventricular geometry and/or valve annulus. Transthoracic echocardiography (TTE) is the initial modality for MR evaluation. Parameters used for the assessment of MR include valve structure, cardiac remodeling, and color and spectral Doppler. Quantitative measurements include effective regurgitant orifice area, regurgitant volume, and regurgitant fraction. Knowledge of advantages and limitations of echo-Doppler parameters is essential for accurate results. An integrative approach is recommended in overall grading of MR as mild, moderate, or severe since singular parameters may be affected by several factors. When the mechanism and/or grade of MR is unclear from the TTE or is discrepant with the clinical scenario, further evaluation with transesophageal echocardiography or cardiac magnetic resonance imaging is recommended, the latter emerging as a powerful MR quantitation tool.

2017 ACC Expert Consensus Decision Pathway on the Management of Mitral Regurgitation: A Report of the American College of Cardiology Task Force on Expert Consensus Decision Pathways

Mitral regurgitation (MR) is a complex valve lesion that can pose significant management challenges for the cardiovascular clinician. This Expert Consensus Document emphasizes that recognition of MR should prompt an assessment of its etiology, mechanism, and severity, as well as indications for treatment. A structured approach to evaluation based on clinical findings, precise echocardiographic imaging, and when necessary, adjunctive testing, can help clarify decision making. Treatment goals include timely intervention by an experienced heart team to prevent left ventricular dysfunction, heart failure, reduced quality of life, and premature death.

Outcomes of ischaemic mitral regurgitation in anterior versus inferior ST elevation myocardial infarction

Background

Ischaemic mitral regurgitation (IMR) is a detrimental complication of ST elevation myocardial infarction (STEMI).

Objective

We sought to determine patient characteristics and outcomes of patients with IMR with focus on anterior or inferior location of STEMI.

Methods

All patients presenting with STEMI complicated by IMR to our centre who underwent primary percutaneous coronary intervention within the first 12 hours of presentation from 1995 to 2014 were included. IMR was graded from 1+ to 4+ within 3 days of index myocardial infarction by echocardiography, divided into 2 groups based on infarct location and outcomes were compared.

Results

Overall, 805 patients were included. There were 302 (17.8%) patients with mitral regurgitation (MR) out of the 1700 patients with anterior STEMI while 503 (21.8%) had MR out of the 2305 patients with inferior STEMI. There was no significant difference between both groups in comorbidities, clinical presentation or door-to-balloon time (DBT; median 104 vs 106 min, p=0.5). 30-day and 1-year mortality were higher in anterior STEMI compared with inferior STEMI (14.9% vs 6.8% and 26.4% vs 14.3%, respectively, p<0.001 both), as well as 5-year mortality (39.7% vs 24.8%, p<0.01). When analysis was performed for each grade of IMR, anterior was associated with worse outcomes in every grade. On multivariate cox survival analysis, after adjustment for age, gender, comorbidities, grade of IMR, ejection fraction and DBT, anterior STEMI was still associated with worse outcomes (HR 1.62 (95% CI 1.23 to 2.12), p<0.001).

Conclusions

Although IMR occurs more frequently with inferior infarction, outcomes are worse following anterior infarction.

Effect of Transcatheter Mitral Annuloplasty With the Cardioband Device on 3-Dimensional Geometry of the Mitral Annulus

This study was performed to assess the acute intraprocedural effects of transcatheter direct mitral annuloplasty using the Cardioband device on 3-dimensional (3D) anatomy of the mitral annulus. Of 45 patients with functional mitral regurgitation (MR) enrolled in a single arm, multicenter, prospective trial, 22 had complete pre- and post-implant 3D transesophageal echocardiography (TEE) images stored in native data format that allowed off-line 3D reconstruction. Images with the highest volume rate and best image quality were selected for analysis. Multiple measurements of annular geometry were compared from baseline to post-implant using paired t tests with Bonferroni correction to account for multiple comparisons. The device was successfully implanted in all patients, and MR was reduced to moderate in 2 patients, mild in 17 patients, and trace in 3 patients after final device cinching. Compared with preprocedural TEE, postprocedural TEE showed statistically significantly reductions in annular circumference (137 ± 15 vs 128 ± 17 mm; p = 0.042), intercommissural distance (42.4 ± 4.3 vs 38.6 ± 4.4 mm; p = 0.029), anteroposterior distance (40.0 ± 5.4 vs 37.0 ± 5.7 mm; p = 0.025), and aortic-mitral angle (117 ± 8° vs 112 ± 8°; p = 0.032). This study demonstrates that transcatheter direct mitral annuloplasty with the Cardioband device results in acute remodeling of the mitral annulus with successful reduction of functional MR.

Comparison of Transesophageal and Transthoracic Echocardiographic Measurements of Mechanism and Severity of Mitral Regurgitation in Ischemic Cardiomyopathy (from the Surgical Treatment of Ischemic Heart Failure Trial)

Mitral regurgitation (MR) is common in ischemic heart disease and contributes to symptoms and mortality. This report compares the results of baseline transesophageal echocardiography (TEE) and transthoracic echocardiography (TTE) imaging of the mechanism and severity of functional MR in patients with ischemic cardiomyopathy in the Surgical Treatment for Ischemic Heart Failure (STICH) trial. Independent core laboratories measured both TTE and TEE images on 196 STICH participants. Common measurements to both models included MR grade, mitral valve tenting height and tenting area, and mitral annular diameter. For each parameter, correlations were assessed using Spearman rank correlation coefficients. A modest correlation was present between TEE and TTE for overall MR grade (n = 176, r = 0.52). For mechanism of MR, modest correlations were present for long-axis tenting height (n = 152, r = 0.35), tenting area (n = 128, r = 0.27), and long-axis mitral annulus diameter (n = 123, r = 0.41). For each measurement, there was significant scatter. Potential explanations for the scatter include different orientation of the imaging planes between TEE and TTE, a mean temporal delay of 6 days between TEE and TTE, and statistically significant differences in heart rate and blood pressure and weight between studies. In conclusion, TEE and TTE measurements of MR mechanism and severity correlate only modestly with enough scatter in the data that they are not interchangeable.

Surgical revascularization is associated with maximal survival in patients with ischemic mitral regurgitation: a 20-year experience

BACKGROUND

The optimal treatment for ischemic mitral regurgitation remains actively debated. Our objective was to evaluate the relationship between ischemic mitral regurgitation treatment strategy and survival.

METHODS AND RESULTS

We retrospectively reviewed patients at our institution diagnosed with significant coronary artery disease and moderate or severe ischemic mitral regurgitation from 1990 to 2009, categorized by medical treatment alone, percutaneous coronary intervention, coronary artery bypass grafting (CABG), or CABG plus mitral valve repair or replacement. Kaplan-Meier methods and multivariable Cox proportional hazards analyses were performed to assess the relationship between treatment strategy and survival, with the use of propensity scores to account for nonrandom treatment assignment. A total of 4989 patients were included: medical treatment alone=36%, percutaneous coronary intervention=26%, CABG=33%, and CABG plus mitral valve repair or replacement=5%. Median follow-up was 5.37 years. Compared with medical treatment alone, significantly lower mortality was observed in patients treated with percutaneous coronary intervention (adjusted hazard ratio, 0.83; 95% confidence interval, 0.76-0.92; P=0.0002), CABG (adjusted hazard ratio, 0.56; 95% confidence interval, 0.51-0.62; P<0.0001), and CABG plus mitral valve repair or replacement (adjusted hazard ratio, 0.69; 95% confidence interval, 0.57-0.82; P<0.0001). There was no significant difference in these results based on mitral regurgitation severity.

CONCLUSIONS

Patients with significant coronary artery disease and moderate or severe ischemic mitral regurgitation undergoing CABG alone demonstrated the lowest risk of death. CABG with or without mitral valve surgery was associated with lower mortality than either percutaneous coronary intervention or medical treatment alone.