Imaging in Minimally Invasive Mitral Valve Repair

Cardiac magnetic resonance imaging in the evaluation and management of mitral valve prolapse - a comprehensive review

Mitral valve prolapse is a common valve disorder that usually has a benign prognosis unless there is significant regurgitation or LV impairment. However, a subset of patients are at an increased risk of ventricular arrhythmias and sudden cardiac death, which has led to the recognition of "arrhythmic mitral valve prolapse" as a clinical entity. Emerging risk factors include mitral annular disjunction and myocardial fibrosis. While echocardiography remains the primary method of evaluation, cardiac magnetic resonance has become crucial in managing this condition. Cine magnetic resonance sequences provide accurate characterization of prolapse and annular disjunction, assessment of ventricular volumes and function, identification of early dysfunction and remodeling, and quantitative assessment of mitral regurgitation when integrated with flow imaging. However, the unique strength of magnetic resonance lies in its ability to identify tissue changes. T1 mapping sequences identify diffuse fibrosis, in turn related to early ventricular dysfunction and remodeling. Late gadolinium enhancement sequences detect replacement fibrosis, an independent risk factor for ventricular arrhythmias and sudden cardiac death. There are consensus documents and reviews on the use of cardiac magnetic resonance specifically in arrhythmic mitral valve prolapse. However, in this article, we propose an algorithm for the broader use of cardiac magnetic resonance in managing this condition in various scenarios. Future advancements may involve implementing techniques for tissue characterization and flow analysis, such as 4D flow imaging, to identify patients with ventricular dysfunction and remodeling, increased arrhythmic risk, and more accurate grading of mitral regurgitation, ultimately benefiting patient selection for surgical therapy.

Identification of Mitral Valve Prolapse on Non-electrocardiography-gated Enhanced Chest Computed Tomography

PURPOSE

The primary imaging modality for the diagnosis of mitral valve prolapse (MVP) is echocardiography supplemented by electrocardiography (ECG)-gated cardiac computed tomography (CT) angiography. However, we have recently encountered patients with MVP who were initially identified on non-ECG-gated enhanced chest CT. The purpose of this study is to evaluate the diagnostic accuracy of non-ECG-gated enhanced chest CT to predict the presence of MVP.

PATIENTS AND METHODS

Of 92 patients (surgically confirmed MVP who underwent non-ECG-gated chest CT), 27 patients were excluded for motion artifact or insufficient surgical correlation, and 65 patients were ultimately included. As a control, 65 patients with dyspnea and without MVP (non-ECG-gated chest CT and echocardiography were performed within 1 month) were randomly selected. We retrospectively analyzed an asymmetric double line sign on axial CT images for the presence of MVP. The asymmetric double line sign was defined as the presence of a linear structure, not located in the plane traversing the mitral annulus.

RESULTS

Use of the asymmetric double line sign to predict MVP on non-ECG-gated CT showed modest sensitivity, high specificity, modest negative predictive value, and high positive predictive value of 59% (38/65), 99% (64/65), 70% (64/91), and 97% (38/39), respectively.

CONCLUSION

The asymmetric double line sign on non-ECG-gated enhanced chest CT may be a valuable finding to predict the presence of MVP. Familiarity with this CT finding may lead to prompt diagnosis and proper management of MVP.

Evaluation of Patients for Percutaneous Edge-to-edge Mitral Valve Repair: Comparison of Cardiac Computed Tomography Angiography With Transesophageal Echocardiography

PURPOSE

We sought to compare parameters derived from cardiac computed tomography angiography (CCTA) with those from transesophageal echocardiography (TEE) for the evaluation of patients with severe mitral regurgitation (MR) before percutaneous edge-to-edge mitral valve repair (PE2E). TEE is the mainstay for PE2E, although it has specific limitations. CCTA enables measurements in any arbitrary plane with high spatial resolution and offers good calcium visibility.

MATERIALS AND METHODS

Patients who underwent TEE and CCTA before scheduled PE2E at 2 medical centers were included in this retrospective analysis. Quantitative parameters relevant for PE2E were obtained from TEE and CCTA in a blinded manner and the intrareviewer variability was assessed.

RESULTS

All 30 patients (15 female, 76±10 y) had secondary MR attributable to ischemic (60%) or nonischemic cardiomyopathy (40%). On comparing parameters from TEE and CCTA, left ventricular end-diastolic diameter was 60±11 versus 64±11 mm (r=0.90), intercommissural mitral annulus was 35±5 versus 35±5 mm (r=0.88), long-axis annulus was 33±5 versus 33±5 mm (r=0.74), the distance between the fossa ovalis and the leaflet coaptation was 42±5 versus 41±5 mm (r=0.81), the anterior mitral leaflet was 21±6 versus 20±7 mm (r=0.81), the posterior mitral leaflet was 13±2 versus 13±2 mm (r=0.91), and the median mitral calcification was 1 (interquartile range: 0 to 2) versus 0 (interquartile range: 0 to 1; r=0.53), respectively. Intrareviewer agreement was good and excellent for continuous and categorical variables, respectively.

CONCLUSIONS

Our data suggest that evaluation of the mitral valve apparatus with CCTA in patients considered for PE2E is feasible, correlates well with TEE, and offers improved calcium visibility. In selected cases, additional information from CCTA may be helpful for achieving optimal interventional results.

ECG-gated Versus Non-ECG-gated High-pitch Dual-source CT for Whole Body CT Angiography (CTA)

RATIONALE AND OBJECTIVES

To investigate motion artifacts, image quality, and practical differences in electrocardiographic (ECG)-gated versus non-ECG-gated high-pitch dual-source computed tomography angiography (CTA) of the whole aorta.

MATERIALS AND METHODS

Two groups, each including 40 patients, underwent either ECG-gated or non-ECG-gated high-pitch dual-source CTA of the whole aorta. The aortic annulus, aortic valve, coronary ostia, and the presence of motion artifacts of the thoracic aorta as well as vascular contrast down to the femoral arteries were independently assessed by two readers. Additional objective parameters including image noise and signal-to-noise ratio were analyzed.

RESULTS

Subjective and objective scoring revealed no presence of motional artifacts regardless of whether the ECG-gated or the non-ECG-gated protocol was used (P > 0.1). Image acquisition parameters (examination length, examination duration, radiation dose) were comparable between the two groups without significant differences. The aortic annulus, aortic valve, and coronary ostia were reliably evaluable in all patients. Vascular contrast was rated excellent in both groups.

CONCLUSIONS

High-pitch dual-source CTA of the whole aorta is a robust and dose-efficient examination strategy for the evaluation of aortic pathologies whether or not ECG gating is used.