The Role of Cardiac Magnetic Resonance in Aortic Stenosis and Regurgitation

Evolving perspectives on aortic stenosis: the increasing importance of evaluating the right ventricle before aortic valve intervention

Aortic stenosis (AS) was historically considered a disease of the left side of the heart, with the main pathophysiological impact being predominantly on the left ventricle (LV). However, progressive pressure overload in AS can initiate a cascade of extra-valvular myocardial remodeling that could also precipitate maladaptive alterations in the structure and function of the right ventricle (RV). The haemodynamic and clinical importance of these changes in patients with AS have been largely underappreciated in the past. Contemporary data indicates that RV dilatation or impairment identifies the AS patients who are at increased risk of adverse clinical outcomes after aortic valve replacement (AVR). It is now increasingly recognised that effective quantitative assessment of the RV plays a key role in delineating the late clinical stage of AS, which could improve patient risk stratification. Despite the increasing emphasis on the pathological significance of RV changes in AS, it remains to be established if earlier detection of these changes can improve the timing for intervention. This review will summarise the features of normal RV physiology and the mechanisms responsible for RV impairment in AS. In addition, we will discuss the multimodality approach to the comprehensive assessment of RV size, function and mechanics in AS patients. Finally, we will review the emerging evidence reinforcing the negative impact of RV dysfunction on clinical outcomes in AS patients treated with AVR.

Role of Cardiovascular Magnetic Resonance in the Assessment of Native Aortic Regurgitation With Insights on Mixed and Multiple Valvular Heart Disease: A Narrative Review

Cardiovascular magnetic resonance imaging (CMR) has received extensive validation for the assessment of valvular heart disease (VHD) and offers an accurate and direct method for the quantification of aortic regurgitation (AR). According to the current guidelines, CMR represents a useful second-line investigation in patients with poor acoustic windows or when echocardiography is inconclusive, for example, in cases of multiple or eccentric aortic jets. Without ionizing radiation exposure, CMR provides in-depth information not only on the severity degree of AR, providing a precise quantification of regurgitant volume and fraction, but also on cardiac structure and function, being recognized as the gold standard for the assessment of heart chamber size and systolic function. CMR allows a free choice of cardiac imaging planes and provides further information on the myocardium, thanks to the tissue characterization ability offered by several sequences, such as the late gadolinium enhancement technique. The possibilities offered by CMR become even more interesting in the context of mixed and multiple VHD, where the echocardiographic assessments often encounter difficulties in the quantification of each single valve lesion. The current scientific data support a greater expansion of CMR in this field, thanks to its additional advantages for the diagnosis, risk stratification, and to guide treatment. This review investigates the current CMR techniques and protocols in AR, with special insights into the evaluation of mixed aortic valve disease and multiple VHD including AR.

Differences between echocardiography and cardiac nuclear magnetic resonance parameters in children with bicuspid aortic valve-related aortopathy

Objectives

The bicuspid aortic valve (BAV) is the most common congenital heart defect. Patients with BAV frequently develop aortopathy, which depends on the dysfunction and morphotype of the BAV.

Aim

The aim of our study was to compare the echocardiography and cardiac magnetic resonance (CMR) findings in BAV patients, and to define the risks of BAV dysfunction and aortopathy.

Methods

The retrospective study included 50 patients (68% male) with BAV, with an average age of 13.6 ± 3.9 years, who underwent a transthoracic echocardiographic examination and CMR at our institute from 2012 to 2020.

Results

The BAV types were evaluated significantly differently by echocardiography and CMR (p = 0.013). 54% of patients had BAV insufficiency on echo and 70% on echo CMR. It was more prevalent in males, older patients, and patients with a higher body surface area. By comparing the degree of insufficiency measured by echo (1+, IQR 0-1), and CMR (0, IQR 0-1), a significant difference was observed (p = 0.04), while a moderate positive correlation was proved (rr = 0.4; p = 0.004). Stenosis was registered in 44% of patients by echo, while 58% had stenosis on CMR. The peak pressure gradient measured by echo was significantly higher than the velocity on CMR (41, IQR 22.7-52.5 mmHg vs. 23, IQR 15.5-35.0 mmHg; p = 0.002). Aortopathy was registered in 76% of patients on echo and 78% on CMR; 38% of patients had severe aortic dilatation on echo and 54% on CMR (p = 0.003). Patients with BAV stenosis on echo had more frequent dilatation of the tubular ascending aorta (15/24 pts; p = 0.02). All patients with BAV insufficiency on CMR had aortopathy (p = 0.04) and had enlargement of the sinus of Valsalva and sinotubular junction. In patients with associated coarctation, the development of aortopathy occurred less frequently than those without coarctation (7/39 vs. 32/39; p = 0.003). The Bland-Altman method, a specific type of scatterplot that is used to visualize the results of comparing two measures, demonstrated the existence of agreement between the two methods, and a level of agreement between the methods of 95% was demonstrated.

Conclusion

Our study indicated significant differences in the measured BAV morphotype and dysfunction when comparing the two diagnostic methods. On the other hand, moderate to strong correlations were found in the evaluated parameters, which indicates the importance of performing noninvasive diagnostic procedures in the follow-up of these patients.

Automated Quantification of Simple and Complex Aortic Flow Using 2D Phase Contrast MRI

(1) Background and Objectives: Flow assessment using cardiovascular magnetic resonance (CMR) provides important implications in determining physiologic parameters and clinically important markers. However, post-processing of CMR images remains labor- and time-intensive. This study aims to assess the validity and repeatability of fully automated segmentation of phase contrast velocity-encoded aortic root plane. (2) Materials and Methods: Aortic root images from 125 patients are segmented by artificial intelligence (AI), developed using convolutional neural networks and trained with a multicentre cohort of 160 subjects. Derived simple flow indices (forward and backward flow, systolic flow and velocity) and complex indices (aortic maximum area, systolic flow reversal ratio, flow displacement, and its angle change) were compared with those derived from manual contours. (3) Results: AI-derived simple flow indices yielded excellent repeatability compared to human segmentation (p < 0.001), with an insignificant level of bias. Complex flow indices feature good to excellent repeatability (p < 0.001), with insignificant levels of bias except flow displacement angle change and systolic retrograde flow yielding significant levels of bias (p < 0.001 and p < 0.05, respectively). (4) Conclusions: Automated flow quantification using aortic root images is comparable to human segmentation and has good to excellent repeatability. However, flow helicity and systolic retrograde flow are associated with a significant level of bias. Overall, all parameters show clinical repeatability.

Aortic Valve Calcium Score: Applications in Clinical Practice and Scientific Research-A Narrative Review

In this narrative review, we investigate the essential role played by the computed tomography Aortic Valve Calcium Score (AVCS) in the cardiovascular diagnostic landscape, with a special focus on its implications for clinical practice and scientific research. Calcific aortic valve stenosis is the most prevalent type of aortic stenosis (AS) in industrialized countries, and due to the aging population, its prevalence is increasing. While transthoracic echocardiography (TTE) remains the gold standard, AVCS stands out as an essential complementary tool in evaluating patients with AS. The advantage of AVCS is its independence from flow; this allows for a more precise evaluation of patients with discordant findings in TTE. Further clinical applications of AVCS include in the assessment of patients before transcatheter aortic valve replacement (TAVR), as it helps in predicting outcomes and provides prognostic information post-TAVR. Additionally, we describe different AVCS thresholds regarding gender and the anatomical variations of the aortic valve. Finally, we discuss various scientific studies where AVCS was applied. As AVCS has some limitations, due to the pathophysiologies of AS extending beyond calcification and gender differences, scientists strive to validate contrast-enhanced AVCS. Furthermore, research on developing radiation-free methods of measuring calcium content is ongoing.

Insights into calcific aortic valve stenosis: a comprehensive overview of the disease and advancing treatment strategies

Aortic valve stenosis is a disease characterized by thickening and narrowing of the aortic valve (AV), most commonly due to calcification, which leads to left ventricular outflow obstruction called calcific aortic valve disease (CAVD). CAVD presents as a progressive clinical syndrome with cardiorespiratory symptoms, often with rapid deterioration. The modern-day pathophysiology of CAVD involves a complex interplay of genetic factors, chronic inflammation, lipid deposition, and valve calcification, with early CAVD stages resembling atherosclerosis. Various imaging modalities have been used to evaluate CAVD, with a recent trend of using advanced imaging to measure numerous AV parameters, such as peak jet velocity. Significant improvements in mortality have been achieved with transcatheter AV repair, but numerous therapeutics and modalities are being researched to delay the progression of CAVD. This article aims to provide a comprehensive review of CAVD, explore recent developments, and provide insights into future treatments with various novel modalities.

Prognostic Value of Cardiac Magnetic Resonance Imaging in Chronic Aortic Regurgitation: A Systematic Review and Meta-Analysis

Background

Chronic aortic regurgitation (AR) is a common valvular disease characterized by an overload of left ventricular volume and pressure. Accurate assessment of the heart from all angles is crucial for effective clinical management and prognostic evaluation of AR patients. As an advanced imaging technique, cardiac magnetic resonance (CMR) has become the gold standard for assessing cardiac volume and function. Accordingly, this study aimed to evaluate the prognostic value of CMR in chronic AR.

Methods

EMBASE, Cochrane Library, PubMed, and Web of Science were searched for clinical studies published between inception and July 19, 2022. Only studies that used CMR to assess patients with chronic isolated AR and provided prognostic data were included.

Results

For our analysis, 11 studies, which involved 1702 subjects and follow-up periods of 0.6-9.7 years, were eligible. We identified 13 CMR-related parameters associated with AR prognosis. With aortic valve surgery as the outcome, we estimated the pooled hazard ratios (HRs) for four of these parameters: aortic regurgitation fraction (ARF), aortic regurgitation volume (ARV), left ventricle end-diastolic volume (LVEDV), and LV end-systolic volume (LVESV). The pooled HR for ARF was found to be 4.31 (95% confidence interval [CI]: 1.12-16.59, p = 0.034), while that for ARV was 3.88 (95% CI: 0.71-21.04, p = 0.116). Additionally, the combined HRs of LVEDV and LVESV were estimated to be 2.20 (95% CI: 1.04-4.67, p = 0.039) and 3.14 (95% CI: 1.22-8.07, p = 0.018), respectively.

Conclusions

The assessment of ARF, LVEDV, and LVESV via CMR has significant prognostic value in predicting the prognosis of AR patients with aortic valve surgery as an endpoint. It is recommended to consider using multi-parameter CMR in the clinical management of AR patients for timely interventions and effective prognostic evaluation.

Advanced Cardiac Imaging in the Assessment of Aortic Stenosis

Aortic stenosis is the most common form of valve disease in the Western world and a major healthcare burden. Although echocardiography remains the central modality for the diagnosis and assessment of aortic stenosis, recently, advanced cardiac imaging with cardiovascular magnetic resonance, computed tomography, and positron emission tomography have provided invaluable pathological insights that may guide the personalized management of the disease. In this review, we discuss applications of these novel non-invasive imaging modalities for establishing the diagnosis, monitoring disease progression, and eventually planning the invasive treatment of aortic stenosis.

Multimodality Imaging of the Neglected Valve: Role of Echocardiography, Cardiac Magnetic Resonance and Cardiac Computed Tomography in Pulmonary Stenosis and Regurgitation

The pulmonary valve (PV) is the least imaged among the heart valves. However, pulmonary regurgitation (PR) and pulmonary stenosis (PS) can occur in a variety of patients ranging from fetuses, newborns (e.g., tetralogy of Fallot) to adults (e.g., endocarditis, carcinoid syndrome, complications of operated tetralogy of Fallot). Due to their complexity, PR and PS are studied using multimodality imaging to assess their mechanism, severity, and hemodynamic consequences. Multimodality imaging is crucial to plan the correct management and to follow up patients with pulmonary valvulopathy. Echocardiography remains the first line methodology to assess patients with PR and PS, but the information obtained with this technique are often integrated with cardiac magnetic resonance (CMR) and computed tomography (CT). This state-of-the-art review aims to provide an updated overview of the usefulness, strengths, and limits of multimodality imaging in patients with PR and PS.

Aortic regurgitation: A multimodality approach

Aortic regurgitation (AR) is a common valvular pathology. Multimodality noninvasive cardiovascular imaging is routinely used to assess the mechanism of AR, degree, and its hemodynamic impact on the cardiovascular system. Collecting this information is crucial in establishing the prognosis and in guiding patient management and follow-up. While echocardiography remains the primary test to assess AR, a comprehensive assessment of this valvulopathy can be obtained by combining the information from different techniques. This state-of-the-art review is intended to provide an update ed overview of the applications, strengths, and limits of transthoracic echocardiography, cardiac magnetic resonance, and cardiac computed tomography in patients with AR.