Cardiac magnetic resonance imaging in patients undergoing percutaneous mitral valve repair with the MitraClip system

Cardiovascular magnetic resonance in patients with mitral valve prolapse

With a prevalence of 2-3% in the general population, mitral valve prolapse (MVP) is the most common valvular heart disease. The clinical course is benign in the majority of patients, although severe mitral regurgitation, heart failure, and sudden cardiac death affect a non-negligible subset of patients. Imaging of MVP was confined to echocardiography until a few years ago when it became apparent that cardiovascular magnetic resonance (CMR) could offer comparative advantages for detecting and quantifying mitral valve abnormalities alongside tissue myocardial characterization. The present review highlights the growing body of evidence supporting the role of CMR in patients with MVP. Based on the recent literature, CMR appears not as a simple alternative to echocardiography in patients with poor acoustic windows, but as a complementary imaging modality instrumental for better quantifying mitral valve abnormalities, mitral regurgitation severity, ventricular remodeling, and myocardial tissue changes. In this respect, pivotal CMR studies highlight that mitral annular disjunction and myocardial fibrosis by late gadolinium enhancement are associated with a heightened risk of life-threatening ventricular arrhythmias (arrhythmic MVP). We also delineate how these and other markers (e.g., the severity of mitral regurgitation) could enable a personalized risk assessment in patients with MVP and implement clinical decision-making. Here, we provide a comprehensive review of the current literature, with an emphasis on the arrhythmic MVP phenotype. The review also provides some practical suggestions on how to carry out a dedicated CMR protocol in MVP and composes a thorough report to inform clinicians on key aspects of this valvular heart disease.

2020 MR Safety for Cardiac Devices: An Update for Radiologists

Magnetic resonance imaging (MRI) is a unique and powerful diagnostic tool that provides images without ionizing radiation and, at times, can be the only modality to properly assess and diagnose some pathologies. Although many patients will need an MRI in their lifetime, many of them are still being unjustly denied access to it due to what were once considered absolute contraindications, including MR nonconditional pacemakers and implantable cardioverter-defibrillators. However, there are a number of large studies that have recently demonstrated that MRI can safely be performed in these patients under certain conditions. In addition, there are an increasing number of novel cardiac devices implanted in patients who may require an MRI. Radiologists need to familiarize themselves with these devices, identify which patients with these devices can safely undergo MRI, and under which conditions. In this article, we will review the current literature on MR safety and cardiac devices, elaborate on how to safely image patients with cardiac devices, and share the expertise of our tertiary cardiac institute.

Myocardial protection: a forgotten modality

The goals of a cardiac surgical procedure are both technical excellence and complete protection of cardiac function. Cardioplegia is used almost universally to protect the heart and provide a quiet bloodless field for surgical accuracy. Yet, despite the importance of myocardial protection in cardiac surgery, manuscripts or dedicated sessions at major meetings on this subject have become relatively rare, as though contemporary techniques now make them unnecessary. Nevertheless, septal dysfunction and haemodynamic support (inotropes, intra-aortic balloon pump, assist devices) are common in postoperative patients, indicating that myocardial damage following cardiac surgery is still prevalent with current cardioplegic techniques and solutions. This article first describes why cardiac enzymes and septal function are the ideal markers for determining the adequacy of myocardial protection. It also describes the underappreciated consequences of postoperative cardiac enzyme release or septal dysfunction (which currently occurs in 40-80% of patients) from inadequate protection, and how they directly correlate with early and especially late mortality. Finally, it reviews the various myocardial protection techniques available to provide a detailed understanding of the cardioplegic methods that can be utilized to protect the heart. This will allow surgeons to critically assess their current method of protection and, if needed, make necessary changes to provide their patients with optimal protection.

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

Cardiac imaging is the cornerstone of defining the etiology, quantification, and management of mitral regurgitation (MR). This continues to be even more so the case with emerging transcatheter techniques to manage MR. Transthoracic echocardiography remains the first-line imaging modality to assess MR but has limitations. Cardiac MRI(CMR) provides the advantages of quantitative nonvisual estimation, 3D volumetric data, late gadolinium, T1, and extracellular volume measurements to comprehensively assess mitral valvular pathology, cardiac remodeling, and the prognostic impact of therapies. This review describes the superiority, technical aspects and growing evidence behind CMR, and lays the roadmap for the future of CMR in MR.

Galectin-3 is associated with left ventricular reverse remodeling and outcome after percutaneous mitral valve repair

BACKGROUND

Plasma Galectin-3 is a marker of myocardial inflammation and fibrosis, was associated with left ventricular (LV) reverse remodeling after conventional surgical mitral valve repair (MVR) and predicted clinical events in patients undergoing transcatheter aortic valve replacement (TAVR). We aimed to evaluate the association between pre-interventional Galectin-3 levels and (1) reverse LV remodeling and (2) major adverse cardiovascular events (MACE) in patients undergoing percutaneous MVR.

METHODS

Forty-four consecutive patients (median age 79 years, LV ejection fraction 39.5 ± 11.4%, 91% in NYHA functional class ≥III) with symptomatic moderate to severe mitral regurgitation undergoing percutaneous MVR were prospectively included. Plasma Galectin-3 levels were measured before the procedure. Echocardiographic and clinical assessment was performed at baseline and after 3 months. LV reverse remodeling was prospectively defined as a ≥10% increase in global longitudinal strain. MACE included death, myocardial infarction, heart failure related rehospitalization and stroke and was assessed after a mean follow-up time of 2 years.

RESULTS

72.7% of the patients showed LV reverse remodeling. Pre-interventional Galectin-3 < 10 ng/ml was an independent predictor of LV reverse remodeling (OR 10.3, 95% CI 1.2-83.9, p = 0.036). 25 patients (56.8%) experienced a MACE. Patients with Galectin-3 levels ≥ 10 ng/ml had significantly more MACE than patients with Galectin-3 levels < 10 ng/ml (100% vs. 45.5%, p = 0.003). Diabetes independently predicted MACE (HR 3.1, 95% CI 1.0-9.4, p = 0.049); Galectin-3 ≥ 10 ng/ml was of borderline significance (HR 2.2, 95% CI 0.9-5.4, p = 0.088).

CONCLUSIONS

Pre-interventional plasma Galectin-3 levels are associated with LV reverse remodeling and with clinical outcome after percutaneous MVR.

Utility of cardiac magnetic resonance for evaluation of mitral regurgitation prior to mitral valve surgery

Mitral regurgitation (MR) is a common cause of morbidity worldwide and an accepted indication for interventional therapies which aim to reduce or resolve adverse clinical outcomes associated with MR. Cardiac magnetic resonance (CMR) provides highly accurate means of assessing MR, including a variety of approaches that can measure MR based on quantitative flow. Additionally, CMR is widely accepted as a reference standard for cardiac chamber quantification, enabling reliable detection of subtle changes in cardiac chamber size and function so as to guide decision-making regarding timing of mitral valve directed therapies. Beyond geometric imaging, CMR enables tissue characterization of ischemia and infarction in the left ventricular (LV) myocardium as well as within the mitral valve apparatus, thus enabling identification of structural substrates for MR. This review provides an overview of established and emerging CMR approaches to measure valvular regurgitation, including relative utility of different approaches for patients with primary or secondary MR. Clinical outcomes studies are discussed with focus on data demonstrating advantages of CMR for guiding diagnosis, risk stratification, and management of patients with known or suspected MR. Comparative data is reviewed with focus on diagnostic performance of CMR in comparison to conventional assessment via echocardiography (echo). Emerging literature is reviewed concerning potential new approaches that utilize CMR tissue characterization to guide clinical decision-making in order to improve therapeutic outcomes and clinical prognosis for patients with MR.

Current challenges in interventional mitral valve treatment

Transcatheter mitral valve therapies have emerged as an alternative option in high surgical risk or inoperable patients with severe and symptomatic mitral regurgitation (MR). As multiple technologies and different approaches will become available in the field of mitral valve interventions, different challenges are emerging, both patient- (clinical challenges) and procedure-related (technical challenges). This review will briefly explore the current open challenges in the evolving fields of interventional mitral valve treatment.

Quantitation of mitral regurgitation after percutaneous MitraClip repair: comparison of Doppler echocardiography and cardiac magnetic resonance imaging

OBJECTIVE

Percutaneous valve intervention for severe mitral regurgitation (MR) using the MitraClip is a novel technology. Quantitative assessment of residual MR by transthoracic echocardiography (TTE) is challenging, with multiple eccentric jets and artifact from the clips. Cardiovascular magnetic resonance (CMR) is the reference standard for left and right ventricular volumetric assessment. CMR phase-contrast flow imaging has superior reproducibility for quantitation of MR compared to echocardiography. The objective of this study was to establish the feasibility and reproducibility of CMR in quantitating residual MR after MitraClip insertion in a prospective study.

METHODS

Twenty-five patients underwent successful MitraClip insertion. Nine were excluded due to non-magnetic resonance imaging (MRI) compatible implants or arrhythmia, leaving 16 who underwent a comprehensive CMR examination at 1.5 T (Siemens Aera) with multiplanar steady state free precession (SSFP) cine imaging (cine CMR), and phase-contrast flow acquisitions (flow CMR) at the mitral annulus atrial to the MitraClip, and the proximal aorta. Same-day echocardiography was performed with two-dimensional (2D) visualization and Doppler. CMR and echocardiographic data were independently and blindly analyzed by expert readers. Inter-rater comparison was made by concordance correlation coefficient (CCC) with 95% confidence intervals (CIs), and Bland-Altman (BA) methods.

RESULTS

Mean age was 79 years, and mean LVEF was 44%±11% by CMR and 54%±16% by echocardiography. Inter-observer reproducibility of echocardiographic visual categorical grading by expert readers was poor, with a CCC of 0.475 (-0.7, 0.74). Echocardiographic Doppler regurgitant fraction reproducibility was modest (CCC 0.59, 0.15-0.84; BA mean difference -3.7%, -38% to 31%). CMR regurgitant fraction reproducibility was excellent (CCC 0.95, 0.86-0.98; BA mean difference -2.4%, -11.9 to 7.0), with a lower mean difference and narrower limits of agreement compared to echocardiography. Categorical severity grading by CMR using published ranges had good inter-observer agreement (CCC 0.86, 0.62-0.95).

CONCLUSIONS

CMR performs very well in the quantitation of MR after MitraClip insertion, with excellent reproducibility compared to echocardiographic methods. CMR is a useful technique for the comprehensive evaluation of residual regurgitation in patients after MitraClip. Technical limitations exist for both techniques, and quantitation remains a challenge in some patients.

Recent developments in echocardiographic imaging

PURPOSE OF REVIEW

This review provides an outline of recent applications related to the use of ultrasonography in various catheter-based procedures for the repair of many valvular abnormalities.

RECENT FINDINGS

Percutaneous interventions are becoming a safe and effective therapeutic modality in the management of various valvular defects. The intrinsic ability of ultrasound to provide real-time accurate assessment of cardiac and valvular structural and functional abnormalities makes this modality distinctively useful in the execution of percutaneous valvular procedures and evaluation of their results.Clinical applications of myocardial deformation and cardiac mechanics have been investigated in an increasing number of clinical applications. Speckle tracking accurately measures myocardial deformation parameters and has been recently applied to the evaluation of mitral insufficiency mechanisms.

SUMMARY

Recent developments in echocardiography are promoting this modality from its traditional role of diagnostic technique into one suitable for aiding in the execution of complex catheter-based procedures and for accurate monitoring of therapeutic response in many clinical settings.