Prognostic value of late gadolinium enhancement on CMR in patients with severe aortic valve disease: a systematic review and meta-analysis

Recent updates on asymptomatic and symptomatic aortic valve stenosis its diagnosis, pathogenesis, management and future perspectives

Aortic stenosis (AS) is very common in mid-aged and elderly patients, and it has been reported to have a negative impact on both short and long-term survival with a high mortality rate. The current study identified methods of diagnosis, incidence, and causes of AS, pathogenesis, intervention and management and future perspectives of Asymptomatic and Symptomatic Aortic stenosis. A systematic literature search was conducted using PubMed, Scopus and CINAHL, using the Mesh terms and key words "Aortic stenosis", "diagnostic criteria", "pathogenesis", "incidence and causes of AS" and" intervention and management strategies". Studies were retained for review after meeting strict inclusion criteria that included studies evaluating Asymptomatic and Symptomatic AS. Studies were excluded if duplicate publication, overlap of patients, subgroup studies of a main study, lack of data on AS severity, case reports and letters to editors. Forty-five articles were selected for inclusion. Incidence of AS across the studies ranged from 3 % to 7 %. Many factors have been associated with incidence and increased risk of AS, highest incidence of AS was described after aortic valve calcification, rheumatic heart disease, degenerative aortic valve disease, bicuspid aortic valve and other factors. AS is common and can be predicted by aortic root calcification volume, rheumatic heart disease, degenerative aortic valve disease, bicuspid aortic valve. Intervention and management for AS patients is a complex decision that takes into consideration multiple factors. On the other hand, there is not enough progress in preventive pharmacotherapy to slow the progression of AS.

Diagnostic Challenges in Aortic Stenosis

Aortic stenosis (AS) is the most prevalent degenerative valvular disease in western countries. Transthoracic echocardiography (TTE) is considered, nowadays, to be the main imaging technique for the work-up of AS due to high availability, safety, low cost, and excellent capacity to evaluate aortic valve (AV) morphology and function. Despite the diagnosis of AS being considered straightforward for a very long time, based on high gradients and reduced aortic valve area (AVA), many patients with AS represent a real dilemma for cardiologist. On the one hand, the acoustic window may be inadequate and the TTE limited in some cases. On the other hand, a growing body of evidence shows that patients with low gradients (due to systolic dysfunction, concentric hypertrophy or coexistence of another valve disease such as mitral stenosis or regurgitation) may develop severe AS (low-flow low-gradient severe AS) with a similar or even worse prognosis. The use of complementary imaging techniques such as transesophageal echocardiography (TEE), multidetector computed tomography (MDTC), or cardiac magnetic resonance (CMR) plays a key role in such scenarios. The aim of this review is to summarize the diagnostic challenges associated with patients with AS and the advantages of a comprehensive multimodality cardiac imaging (MCI) approach to reach a precise grading of the disease, a crucial factor to warrant an adequate management of patients.

The Chinese Experience of Imaging in Cardiac Intervention: A Bird's Eye Review

Recent scientific and technological advances have greatly contributed to the development of medical imaging that could enable specific functions. It has become the primary focus of cardiac intervention in preoperative assessment, intraoperative guidance, and postoperative follow-up. This review provides a contemporary overview of the Chinese experience of imaging in cardiac intervention in recent years.

Current and new imaging techniques in risk stratification of asymptomatic severe aortic stenosis

Aortic stenosis (AS) is one of the most common valvular diseases in clinical practice. The prevalence of calcified AS with moderate or severe stenosis exceeds 2% after 75 years. The optimal timing of intervention for asymptomatic severe AS is uncertain and controversial. Identification of high-risk patients is based on echocardiographic parameters (left ventricular dysfunction, AS severity and progression), hemodynamic response to exercise, pulmonary hypertension, and elevated brain natriuretic peptides. However, early surgical aortic valve replacement (AVR), when compared to the watchful waiting approach, was associated with survival advantage. Moreover, new insights into pathophysiology of AS and advances in imaging modalities were helpful in the management of asymptomatic AS. In this report, we detail the potential role of echocardiography to guide timing of surgery and we discussed the use of early risk features based on recent imaging modalities.

The Role of Cardiac Magnetic Resonance in Aortic Stenosis and Regurgitation

Cardiac magnetic resonance (CMR) imaging is a well-set diagnostic technique for assessment of valvular heart diseases and is gaining ground in current clinical practice. It provides high-quality images without the administration of ionizing radiation and occasionally without the need of contrast agents. It offers the unique possibility of a comprehensive stand-alone assessment of the heart including biventricular function, left ventricle remodeling, myocardial fibrosis, and associated valvulopathies. CMR is the recognized reference for the quantification of ventricular volumes, mass, and function. A particular strength is the ability to quantify flow, especially with new techniques which allow accurate measurement of stenosis and regurgitation. Furthermore, tissue mapping enables the visualization and quantification of structural changes in the myocardium. In this way, CMR has the potential to yield important prognostic information predicting those patients who will progress to surgery and impact outcomes. In this review, the fundamentals of CMR in assessment of aortic valve diseases (AVD) are described, together with its strengths and weaknesses. This state-of-the-art review provides an updated overview of CMR potentials in all AVD issues, including valve anatomy, flow quantification, ventricular volumes and function, and tissue characterization.

Evaluating Out-of-Hospital 30-Day Mortality After Transfemoral Transcatheter Aortic Valve Replacement: An STS/ACC TVT Analysis

OBJECTIVES

This study sought to better understand out-of-hospital 30-day mortality following transfemoral transcatheter aortic valve replacement (TAVR) and identify factors associated with poor outcomes.

BACKGROUND

Despite improvements in outcomes with TAVR for severe aortic stenosis, out-of-hospital 30-day mortality has not been evaluated.

METHODS

This study examined patients in the Society of Thoracic Surgeons/American College of Cardiology TVT (Transcatheter Valve Therapy) Registry undergoing TAVR for severe aortic stenosis from January 2015 to March 2018. Primary and secondary endpoints were 30-day out-of-hospital all-cause mortality and out-of-hospital cardiovascular mortality, respectively. Logistic regression models were used to assess association between pre-specified factors and endpoints.

RESULTS

A total of 106,749 patients underwent TAVR and were eligible for analysis. Transfemoral TAVR was performed in 92.3% of patients. A total of 2,137 (2.2%) transfemoral patients died within 30 days of the procedure, and 623 (29%) patients of these patients experienced out-of-hospital 30-day mortality. Cardiovascular and pulmonary etiologies accounted for the majority of observed mortality. Multivariable regression analysis identified older age, gender, lower body surface area, lower left ventricular ejection fraction, lower hemoglobin, atrial fibrillation or flutter, severe lung disease, home oxygen use, lack of moderate-to-severe aortic insufficiency, urgent TAVR, lower Kansas City Cardiomyopathy Questionnaire score, longer hospital length of stay, and in-hospital complications as being independently associated with the primary endpoint. New onset or pre-existent atrial fibrillation or flutter was also independently associated with 30-day out-of-hospital cardiovascular mortality in the transfemoral population.

CONCLUSIONS

We identified 30-day all-cause mortality rate for TAVR of 2.2%. Approximately one-third of patients experienced out-of-hospital mortality at 30 days. Several factors were identified as being independently associated with 30-day out-of-hospital all-cause and cardiovascular mortality. Further work is needed to understand how best to improve out-of-hospital mortality following TAVR.

Impact of myocardial fibrosis on left ventricular remodelling, recovery, and outcome after transcatheter aortic valve implantation in different haemodynamic subtypes of severe aortic stenosis

Aims 

Myocardial fibrosis (MF) might represent a key player in pathophysiology of heart failure in aortic stenosis (AS). We aimed to assess its impact on left ventricular (LV) remodelling, recovery, and mortality after transcatheter aortic valve implantation (TAVI) in different AS subtypes.

Methods and results 

One hundred patients with severe AS were prospectively characterized clinically and echocardiographically at baseline (BL), 6 months, 1 year, and 2 years following TAVI. Left ventricular biopsies were harvested after valve deployment. Myocardial fibrosis was assessed after Masson’s trichrome staining, and fibrotic area was calculated as percentage of total tissue area. Patients were stratified according to MF above (MF+) or below (MF−) median percentage MF (≥11% or <11%). Myocardial fibrosis burden differed significantly between AS subtypes, with highest levels in low ejection fraction (EF), low-gradient AS and lowest levels in normal EF, high-gradient AS (29.5 ± 26.4% vs. 13.5 ± 16.1%, P = 0.003). In the entire cohort, MF+ was significantly associated with poorer LV function, higher extent of pathological LV remodelling, and more pronounced clinical heart failure at BL. After TAVI, MF+ was associated with a delay in normalization of LV geometry and function but not per se with absence of reverse remodelling and clinical improvement. However, 22 patients died during follow-up (mean, 11 months), and 14 deaths were classified as cardiovascular (CV) (n = 9 arrhythmia-associated). Importantly, 13 of 14 CV deaths occurred in MF+ patients (CV mortality 26.5% in MF+ vs. 2% in MF− patients, P = 0.0003). Multivariate analysis identified MF+ as independent predictor of CV mortality [hazard ratio (HR) 27.4 (2.0–369), P = 0.01].

Conclusion 

Histological MF is associated with AS-related pathological LV remodelling and independently predicts CV mortality after TAVI.

Cardiovascular Magnetic Resonance Imaging and Heart Failure

Purpose of Review

The purpose of this review is to summarize the application of cardiac magnetic resonance (CMR) in the diagnostic and prognostic evaluation of patients with heart failure (HF).

Recent Findings

CMR is an important non-invasive imaging modality in the assessment of ventricular volumes and function and in the analysis of myocardial tissue characteristics. The information derived from CMR provides a comprehensive evaluation of HF. Its unique ability of tissue characterization not only helps to reveal the underlying etiologies of HF but also offers incremental prognostic information.

Summary

CMR is a useful non-invasive tool for the diagnosis and assessment of prognosis in patients suffering from heart failure.

Imaging diagnosis of aortic stenosis

Aortic valve stenosis (AS) is the commonest primary valve disorder with increasing prevalence with age. Trans-thoracic echocardiogram is the main imaging technique used to diagnose AS, but discrepancy in diagnosis has been described in almost one third of cases. Other imaging methods, particularly electrocardiogram (ECG)-gated computed tomography, have now emerged to further clarify the diagnosis of AS by both demonstrating the degree of calcification in the valve as well as aortic valve area. Cardiac magnetic resonance imaging allows accurate quantification of ventricular function and evaluation of the myocardium. This paper provides a comprehensive review of the diagnosis of AS for the radiologist.

Usefulness of Cardiac Magnetic Resonance Imaging in Aortic Stenosis

The objective of this review is to provide an overview of the role of cardiac magnetic resonance (CMR) in aortic stenosis (AS). Although CMR is undeniably the gold standard for assessing left ventricular volume, mass, and function, the assessment of the left ventricular repercussions of AS by CMR is not routinely performed in clinical practice, and its role in evaluating and quantifying AS is not yet well established. CMR is an imaging modality integrating myocardial function and disease, which could be particularly useful in a pathology like AS that should be considered as a global myocardial disease rather than an isolated valve disease. In this review, we discuss the emerging potential of CMR for the diagnosis and prognosis of AS. We detail its utility for studying all aspects of AS, including valve anatomy, flow quantification, left ventricular volumes, mass, remodeling, and function, tissue mapping, and 4-dimensional flow magnetic resonance imaging. We also discuss different clinical situations where CMR could be useful in AS, for example, in low-flow low-gradient AS to confirm the low-flow state and to understand the reason for the left ventricular dysfunction or when there is a suspicion of associated cardiac amyloidosis.

The Prognostic Role of Late Gadolinium Enhancement in Aortic Stenosis: A Systematic Review and Meta-Analysis

OBJECTIVES

The aim of this systematic review was to explore the prognostic value of late gadolinium enhancement (LGE) in patients with aortic stenosis (AS).

BACKGROUND

Myocardial fibrosis is a common feature of many cardiac diseases. Cardiac magnetic resonance (CMR) has the ability to noninvasively detect regional fibrosis by using the LGE technique. Several studies have explored whether LGE is associated with adverse outcome in patients with AS.

METHODS

Electronic databases were searched to identify studies investigating the ability of LGE to predict all-cause mortality in patients with AS. A random effects model meta-analysis was conducted. Heterogeneity was assessed with the I2 statistic.

RESULTS

Six studies comprising 1,151 patients met our inclusion criteria. LGE was present in 49.1% of patients with AS. In the pooled analysis, LGE was found to be a strong univariate predictor of all-cause mortality (pooled unadjusted odds ratio: 2.56; 95% confidence interval: 1.83 to 3.57; I2 = 0%). Four of the included studies reported adjusted hazard ratios for mortality. LGE was independently associated with mortality, even after adjusting for baseline characteristics (pooled adjusted hazard ratio: 2.50; 95% confidence interval: 1.64 to 3.83; I2 = 0%).

CONCLUSIONS

Fibrosis on LGE-CMR is a powerful predictor of all-cause mortality in patients with AS and may serve as a novel marker for risk stratification. Future studies should explore whether LGE-CMR can also be used to optimize timing of AS-related interventions.

Left Ventricular Morphology and Function as a Determinant of Pulmonary Hypertension in Patients with Severe Aortic Stenosis: Cardiovascular Magnetic Resonance Imaging Study

Background and Objectives: The influence of cardiac magnetic resonance (CMR) derived left ventricular (LV) parameters on the prognosis of patients with aortic stenosis (AS) was analyzed in several studies. However, the data on the relations between the LV parameters and the development of pulmonary hypertension (PH) in severe AS is lacking. Our objectives were to evaluate the CMR-derived changes of the LV size, morphology, and function in patients with isolated severe AS and PH, and to investigate the prognostic impact of these parameters on elevated systolic pulmonary artery pressure (sPAP). Materials and Methods: Thirty patients with isolated severe AS (aortic valve area ≤1 cm²) underwent a 2D-echocardiography (2D echo) and CMR before aortic valve replacement. Indices of the LV mass and volumes and ejection fraction were analyzed by CMR. The LV global longitudinal (LV LGS) and circumferential strain (LV CS) were calculated using CMR feature tracking (CMR-FT) software (Medis Suite QStrain 2.0, Medis Medical Imaging Systems B.V., Leiden, The Netherlands). The LV fibrosis expansion was assessed using a late gadolinium enhancement sequence. PH was defined as having an estimated sPAP of ≥45 mm Hg. The statistical analysis as performed using SPSS version 23.0 (SPSS, Chicago, IL, USA) Results: 30 patients with severe AS were included in the study, 23% with severe isolated AS had PH (mean sPAP 55 ± 6.6 mm Hg). More severe LV anatomical and functional abnormalities were observed in patients with PH when compared with patients without PH-a higher LV end-diastolic volume index (EDVi) (140 [120.0-160.0] vs. 90.0 mL/m² [82.5-103.0], p = 0.04), larger LV fibrosis area (7.8 [5.6-8.0] vs. 1.3% [1.2-1.5], p = 0.005), as well as lower LV global longitudinal strain (GLS; -14.0 [-14.9-(-8.9)] vs. -21.1% [-23.4-(-17.8)], p = 0.004). By receiver-operating characteristic (ROC) curve analysis, LV EDVi > 107.7 mL/m² (Area Under the Curve (AUC) 95.7%), LV GLS < -15.5% (AUC 86.3%), and LV fibrosis area >5% (AUC 89.3) were found to be robust predictors of PH in severe AS patients. Conclusions: In patients with severe aortic stenosis, a larger end-diastolic LV volume, impaired LV global longitudinal strain, and larger LV fibrosis extent can predict the development of pulmonary hypertension.

Imaging and Impact of Myocardial Fibrosis in Aortic Stenosis

Aortic stenosis is characterized both by progressive valve narrowing and the left ventricular remodeling response that ensues. The only effective treatment is aortic valve replacement, which is usually recommended in patients with severe stenosis and evidence of left ventricular decompensation. At present, left ventricular decompensation is most frequently identified by the development of typical symptoms or a marked reduction in left ventricular ejection fraction <50%. However, there is growing interest in using the assessment of myocardial fibrosis as an earlier and more objective marker of left ventricular decompensation, particularly in asymptomatic patients, where guidelines currently rely on nonrandomized data and expert consensus. Myocardial fibrosis has major functional consequences, is the key pathological process driving left ventricular decompensation, and can be divided into 2 categories. Replacement fibrosis is irreversible and identified using late gadolinium enhancement on cardiac magnetic resonance, while diffuse fibrosis occurs earlier, is potentially reversible, and can be quantified with cardiac magnetic resonance T1 mapping techniques. There is a substantial body of observational data in this field, but there is now a need for randomized clinical trials of myocardial imaging in aortic stenosis to optimize patient management. This review will discuss the role that myocardial fibrosis plays in aortic stenosis, how it can be imaged, and how these approaches might be used to track myocardial health and improve the timing of aortic valve replacement.