Role of T2 mapping in left ventricular reverse remodeling after TAVR

Shaping the Optimal Timing for Treatment of Isolated Asymptomatic Severe Aortic Stenosis with Preserved Left Ventricular Ejection Fraction: The Role of Non-Invasive Diagnostics Focused on Strain Echocardiography and Future Perspectives

The optimal timing for treatment of patients with isolated asymptomatic severe aortic stenosis and preserved left ventricular ejection fraction is still controversial and research is ongoing. Once a diagnosis has been performed and other cardiac comorbidities (e.g., concomitant significant valvulopathies or infiltrative cardiomyopathies) have reasonably been excluded, a hot topic is adequate myocardial characterization, which aims to prevent both myocardial dysfunction and subsequent adverse myocardial remodeling, and can potentially compromise the post-treatment outcomes. Another crucial subject of debate is the assessment of the real "preserved" left ventricular ejection fraction cut-off value in the presence of isolated asymptomatic severe aortic stenosis, in order to optimize the timing of aortic valve replacement as well. The aim of the present critical narrative review is highlighting the current role of non-invasive diagnostics in such a setting, focusing on strain echocardiography, and citing the main complementary cardiac imaging techniques, as well as suggesting potential implementation strategies in routine clinical practice in view of future developments.

SGLT2-inhibitors in diabetic patients with severe aortic stenosis and cardiac damage undergoing transcatheter aortic valve implantation (TAVI)

BACKGROUND

A substantial number of patients with severe aortic stenosis (AS) undergoing transcatheter aortic valve implantation (TAVI) experience adverse events after TAVI, with health care expenditure. We aimed to investigate cardiac remodeling and long-term outcomes in diabetic patients with severe AS, left ventricular ejection fraction (LVEF) < 50%, and extra-valvular cardiac damage (EVCD) undergoing TAVI treated with sodium-glucose cotransporter-2 inhibitors (SGLT2i) versus other glucose-lowering strategies (no-SGLT2i users).

METHODS

Multicenter international registry of consecutive diabetic patients with severe AS, LVEF < 50%, and EVCD undergoing TAVI. Based on glucose-lowering therapy at hospital discharge, patients were stratified in SGLT2i versus no-SGLT2i users. The primary endpoint was a composite of all-cause death and heart failure (HF)-hospitalization (major adverse cardiovascular events, MACE) at 2-year follow-up. Secondary outcomes included all-cause death, cardiovascular death, and HF hospitalization.

RESULTS

The study population included 311 patients, among which 24% were SGLT2i users. Within 1-year after TAVI, SGLT2i users experienced a higher rate of LV recovery (p = 0.032), especially those with baseline LVEF ≤ 30% (p = 0.026), despite the lower baseline LVEF. Patients not treated with SGLT2i were more likely to progress to a worse EVCD stage over time (p = 0.018). At 2-year follow-up, SGLT2i use was associated with a lower rate of MACE, all-cause death, and HF hospitalization (p < 0.01 for all). After adjusting for confounding factors, the use of SGLT2i emerged as an independent predictor of reduced MACE (HR = 0.45; 95% CI 0.17-0.75; p = 0.007), all-cause death (HR = 0.51; 95% CI 0.25-0.98; p = 0.042) and HF-hospitalization (HR = 0.40; 95% CI 0.27-0.62; p = 0.004).

CONCLUSIONS

In diabetic patients with severe AS, LVEF < 50%, and EVCD undergoing TAVI, the use of SGLT2i was associated with a more favorable cardiac remodeling and a reduced risk of MACE at 2-year follow-up.

NT-pro-BNP Level is Related to Left Ventricular Remodeling in Patients With Primary Aldosteronism

AIMS

To assess the relationship between the left ventricular remodeling parameters of cardiac magnetic resonance and NT-pro-BNP in patients with primary aldosteronism (PA).

METHODS

Seventy-four PA and 39 essential hypertension patients were prospectively recruited and underwent cardiac magnetic resonance. Plasma NT-pro-BNP was measured before patients underwent cardiac magnetic resonance. Left ventricular remodeling parameters were defined as left ventricular function parameters, T1 mapping parameters, and strain parameters. Differences in continuous variables between two groups were analyzed using Student's t-test or Mann-Whitney U test. Differences in categorical variables between two groups were analyzed by chi-squared test. Spearman's correlation and linear regression were used to analyze the relationships between left ventricular remodeling parameters and plasma NT-Pro-BNP level. P<0.05 was considered as statistically significant.

RESULTS

Patients with PA demonstrated higher NT-pro-BNP [86.0 (49.5, 145.5) vs. 45.0 (28.5, 73.5) pg/mL, P=0.001] and Native T1 (1227±41 vs. 1206±43 ms, P=0.015) level than essential hypertension patients. Compared to patients with normal NT-pro-BNP levels, those with abnormal levels demonstrated different left ventricular remodeling parameters. NT-pro-BNP level was independently related to native T1 (β=0.316, P=0.006), extracellular volume (β=0.419, P<0.001), short-axis global circumferential strain (β=0.429, P<0.001), four-chamber global longitudinal strain (β=0.332, P=0.002), and four-chamber global radial strain (β=-0.334, P=0.004) in patients after adjusting for baseline characteristics.

CONCLUSIONS

NT-pro-BNP level was related to left ventricular remodeling parameters derived from cardiac magnetic resonance in patients with PA. This result implies that clinicians should pay attention to NT-pro-BNP assessment in patients with PA in routine clinical assessment.

Left ventricular reverse remodeling after transcatheter aortic valve replacement for predominant aortic stenosis and mixed aortic valve disease

BACKGROUND

Mixed aortic valve disease (MAVD) is a frequent concomitant valve disease with unique cardiac pathological changes compared to predominant aortic stenosis (PAS). The previous studies about the MAVD are contradictory. Therefore, a new perspective is needed to assess the value of TAVR for this cohort of patients.

METHODS

From January 2018 to December 2021, 90 MAVD patients and 72 PAS patients who underwent TAVR in our hospital were collected. 1:1 propensity score matching analysis was used to control the bias in patient selection. The dynamic changes in left ventricular morphology and hemodynamics were compared by generalized estimating equations. Univariate or multivariate logistic regression analysis was used to screen for independent risk factors for the non-occurrence of left ventricular reverse remodeling (non-LVRR).

RESULTS

After the matching procedure, 112 patients were included in the analysis (56 in each group). Baseline characteristics were similar between the two groups. LVRR occurred in both groups, but MAVD had greater left ventricular end-diastolic volume index and left ventricular mass index, a higher incidence of mitral regurgitation (MR), and a more pronounced transformation of ventricular geometry patterns. Post-operative MR (odd ratio [OR]: 10.05; 95% confidence interval [CI]: 2.08-48.57; p < .001) and coronary artery disease (OR: 2.82; 95% CI: 1.08-7.34; p = .034) were independent risk factors for non-LVRR.

CONCLUSION

LVRR also occurs in patients with MAVD, post-operative MR and coronary artery disease were independent risk factors for non-LVRR.

Multi-modality imaging in aortic stenosis: an EACVI clinical consensus document

In this EACVI clinical scientific update, we will explore the current use of multi-modality imaging in the diagnosis, risk stratification, and follow-up of patients with aortic stenosis, with a particular focus on recent developments and future directions. Echocardiography is and will likely remain the key method of diagnosis and surveillance of aortic stenosis providing detailed assessments of valve haemodynamics and the cardiac remodelling response. Computed tomography (CT) is already widely used in the planning of transcutaneous aortic valve implantation. We anticipate its increased use as an anatomical adjudicator to clarify disease severity in patients with discordant echocardiographic measurements. CT calcium scoring is currently used for this purpose; however, contrast CT techniques are emerging that allow identification of both calcific and fibrotic valve thickening. Additionally, improved assessments of myocardial decompensation with echocardiography, cardiac magnetic resonance, and CT will become more commonplace in our routine assessment of aortic stenosis. Underpinning all of this will be widespread application of artificial intelligence. In combination, we believe this new era of multi-modality imaging in aortic stenosis will improve the diagnosis, follow-up, and timing of intervention in aortic stenosis as well as potentially accelerate the development of the novel pharmacological treatments required for this disease.

Heart failure and excess mortality after aortic valve replacement in aortic stenosis

INTRODUCTION

In aortic stenosis (AS), the heart transitions from adaptive compensation to an AS cardiomyopathy and eventually leads to decompensation with heart failure. Better understanding of the underpinning pathophysiological mechanisms is required in order to inform strategies to prevent decompensation.

AREAS COVERED

In this review, we therefore aim to appraise the current pathophysiological understanding of adaptive and maladaptive processes in AS, appraise potential avenues of adjunctive therapy before or after AVR and highlight areas of further research in the management of heart failure post AVR.

EXPERT OPINION

Tailored strategies for the timing of intervention accounting for individual patient's response to the afterload insult are underway, and promise to guide better management in the future. Further clinical trials of adjunctive pharmacological and device therapy to either cardioprotect prior to intervention or promote reverse remodeling and recovery after intervention are needed to mitigate the risk of heart failure and excess mortality.

Left Ventricular Systolic Dysfunction in Aortic Stenosis: Pathophysiology, Diagnosis, Management, and Future Directions

Degenerative calcific aortic stenosis (AS) is the most common valvular heart disease and often co-exists with left ventricular (LV) systolic dysfunction at the time of diagnosis. Impaired LV systolic function has been associated with worse outcomes in the setting of AS, even after successful aortic valve replacement (AVR). Myocyte apoptosis and myocardial fibrosis are the 2 key mechanisms responsible for the transition from the initial adaptation phase of LV hypertrophy to the phase of heart failure with reduced ejection fraction. Novel advanced imaging methods, based on echocardiography and cardiac magnetic resonance imaging, can detect LV dysfunction and remodeling at an early and reversible stage, with important implications for the optimal timing of AVR especially in patients with asymptomatic severe AS. Furthermore, the advent of transcatheter AVR as a first-line treatment for AS with excellent procedural outcomes, and evidence that even moderate AS portends worse prognosis in heart failure with reduced ejection fraction patients, has raised the question of early valve intervention in this patient population. With this review, we describe the pathophysiology and outcomes of LV systolic dysfunction in the setting of AS, present imaging predictors of LV recovery after AVR, and discuss future directions in the treatment of AS extending beyond the traditional indications defined in the current guidelines.

T2 and T2⁎ mapping and weighted imaging in cardiac MRI

Cardiac imaging is progressing from simple imaging of heart structure and function to techniques visualizing and measuring underlying tissue biological changes that can potentially define disease and therapeutic options. These techniques exploit underlying tissue magnetic relaxation times: T₁, T₂ and T₂*. Initial weighting methods showed myocardial heterogeneity, detecting regional disease. Current methods are now fully quantitative generating intuitive color maps that do not only expose regionality, but also diffuse changes - meaning that between-scan comparisons can be made to define disease (compared to normal) and to monitor interval change (compared to old scans). T₁ is now familiar and used clinically in multiple scenarios, yet some technical challenges remain. T₂ is elevated with increased tissue water - oedema. Should there also be blood troponin elevation, this oedema likely reflects inflammation, a key biological process. T₂* falls in the presence of magnetic/paramagnetic materials - practically, this means it measures tissue iron, either after myocardial hemorrhage or in myocardial iron overload. This review discusses how T₂ and T₂^⁎ imaging work (underlying physics, innovations, dependencies, performance), current and emerging use cases, quality assurance processes for global delivery and future research directions.

T2 mapping in myocardial disease: a comprehensive review

Cardiovascular magnetic resonance (CMR) is considered the gold standard imaging modality for myocardial tissue characterization. Elevated transverse relaxation time (T2) is specific for increased myocardial water content, increased free water, and is used as an index of myocardial edema. The strengths of quantitative T2 mapping lie in the accurate characterization of myocardial edema, and the early detection of reversible myocardial disease without the use of contrast agents or ionizing radiation. Quantitative T2 mapping overcomes the limitations of T2-weighted imaging for reliable assessment of diffuse myocardial edema and can be used to diagnose, stage, and monitor myocardial injury. Strong evidence supports the clinical use of T2 mapping in acute myocardial infarction, myocarditis, heart transplant rejection, and dilated cardiomyopathy. Accumulating data support the utility of T2 mapping for the assessment of other cardiomyopathies, rheumatologic conditions with cardiac involvement, and monitoring for cancer therapy-related cardiac injury. Importantly, elevated T2 relaxation time may be the first sign of myocardial injury in many diseases and oftentimes precedes symptoms, changes in ejection fraction, and irreversible myocardial remodeling. This comprehensive review discusses the technical considerations and clinical roles of myocardial T2 mapping with an emphasis on expanding the impact of this unique, noninvasive tissue parameter.

Cardiac remodelling - Part 2: Clinical, imaging and laboratory findings. A review from the Study Group on Biomarkers of the Heart Failure Association of the European Society of Cardiology

In patients with heart failure, the beneficial effects of drug and device therapies counteract to some extent ongoing cardiac damage. According to the net balance between these two factors, cardiac geometry and function may improve (reverse remodelling, RR) and even completely normalize (remission), or vice versa progressively deteriorate (adverse remodelling, AR). RR or remission predict a better prognosis, while AR has been associated with worsening clinical status and outcomes. The remodelling process ultimately involves all cardiac chambers, but has been traditionally evaluated in terms of left ventricular volumes and ejection fraction. This is the second part of a review paper by the Study Group on Biomarkers of the Heart Failure Association of the European Society of Cardiology dedicated to ventricular remodelling. This document examines the proposed criteria to diagnose RR and AR, their prevalence and prognostic value, and the variables predicting remodelling in patients managed according to current guidelines. Much attention will be devoted to RR in patients with heart failure with reduced ejection fraction because most studies on cardiac remodelling focused on this setting.

Cardiac magnetic resonance T2 mapping and feature tracking in athlete's heart and HCM

Objectives

Distinguishing hypertrophic cardiomyopathy (HCM) from left ventricular hypertrophy (LVH) due to systematic training (athlete’s heart, AH) from morphologic assessment remains challenging. The purpose of this study was to examine the role of T2 mapping and deformation imaging obtained by cardiovascular magnetic resonance (CMR) to discriminate AH from HCM with (HOCM) or without outflow tract obstruction (HNCM).

Methods

Thirty-three patients with HOCM, 9 with HNCM, 13 strength-trained athletes as well as individual age- and gender-matched controls received CMR. For T2 mapping, GRASE-derived multi-echo images were obtained and analyzed using dedicated software. Besides T2 mapping analyses, left ventricular (LV) dimensional and functional parameters were obtained including LV mass per body surface area (LVMi), interventricular septum thickness (IVS), and global longitudinal strain (GLS).

Results

While LVMi was not significantly different, IVS was thickened in HOCM patients compared to athlete’s. Absolute values of GLS were significantly increased in patients with HOCM/HNCM compared to AH. Median T2 values were elevated compared to controls except in athlete’s heart. ROC analysis revealed T2 values (AUC 0.78) and GLS (AUC 0.91) as good parameters to discriminate AH from overall HNCM/HOCM.

Conclusion

Discrimination of pathologic from non-pathologic LVH has implications for risk assessment of competitive sports in athletes. Multiparametric CMR with parametric T2 mapping and deformation imaging may add information to distinguish AH from LVH due to HCM.

Key Points

• Structural analyses using T2 mapping cardiovascular magnetic resonance imaging (CMR) may help to further distinguish myocardial diseases.

• To differentiate pathologic from non-pathologic left ventricular hypertrophy, CMR including T2 mapping was obtained in patients with hypertrophic obstructive/non-obstructive cardiomyopathy (HOCM/HNCM) as well as in strength-trained athletes.

• Elevated median T2 values in HOCM/HNCM compared with athlete’s may add information to distinguish athlete’s heart from pathologic left ventricular hypertrophy.

Cardiac structural changes after transcatheter aortic valve replacement: systematic review and meta-analysis of cardiovascular magnetic resonance studies

BACKGROUND

Transcatheter aortic valve replacement (TAVR) is increasingly used to treat patients with severe aortic stenosis (AS). Cardiovascular magnetic resonance imaging (CMR) provides reliable and reproducible estimates for assessment of cardiac structure and function after TAVR. The goal of this study was to conduct a systematic review and meta-analysis of the literature to assess left ventricular (LV) volumes, mass and function by CMR after TAVR.

METHODS

Using Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines, we searched PubMed and Embase for studies reporting CMR findings before and at least 1 month after TAVR. Main factors of interest were LV end-diastolic volume index (LVEDVi), LV end-systolic volume index (LVESVi), LV mass index (LVMi), and left ventricular ejection fraction (LVEF). Standardized mean differences (SMD) were pooled by random effects meta-analytic techniques.

RESULTS

Of 453 screened publications, 10 studies (published between 2012 and 2018) were included. A total of 305 patients completed pre- and post-TAVR follow-up CMR (mean age range 78.6-85.0 years, follow-up range 6-15 months). Random effects analysis showed TAVR resulted in reduced LVEDVi (SMD: -0.25, 95% CI: - 0.43 to - 0.07, P = 0.006), LVESVi (SMD: -0.24, 95% CI: - 0.44 to - 0.05, P = 0.01), LVMi (SMD: -0.82, 95% CI: - 1.0 to - 0.63, P < 0.001) and increased LVEF (SMD: 22, 95% CI: 6 to 38%, P = 0.006). Heterogeneity across studies was low (I2: 0%, Pheterogeneity > 0.05 for all). The median reduction was 4 ml/m2 (IQR: 3.1 to 8.2) for LVEDVi, 5 ml/m2 (IQR: 3.0 to 6.0) for LVESVi, and 15.1 g/m2 (IQR: 11.8 to 18.3) for LVMi. The median increase for LVEF was 3.4% (IQR 1.0 to 4.6%).

CONCLUSIONS

CMR demonstrates reverse LV remodeling occurrs within 6-15 months after TAVR, with reductions in LVEDVi, LVESVi and LVMi, and increased LVEF.

Quantitative cardiac MRI

Cardiac MRI has become an indispensable imaging modality in the investigation of patients with suspected heart disease. It has emerged as the gold standard test for cardiac function, volumes, and mass and allows noninvasive tissue characterization and the assessment of myocardial perfusion. Quantitative MRI already has a key role in the development and incorporation of machine learning in clinical imaging, potentially offering major improvements in both workflow efficiency and diagnostic accuracy. As the clinical applications of a wide range of quantitative cardiac MRI techniques are being explored and validated, we are expanding our capabilities for earlier detection, monitoring, and risk stratification of disease, potentially guiding personalized management decisions in various cardiac disease models. In this article we review established and emerging quantitative techniques, their clinical applications, highlight novel advances, and appraise their clinical diagnostic potential. Level of Evidence: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2020;51:693-711.