Echocardiographic and Histologic Correlations in Patients with Severe Aortic Stenosis: Influence of Overweight and Obesity

Impact of aortic valve stenosis on myocardial deformation in different left ventricular levels: A three-dimensional speckle tracking echocardiography study

BACKGROUND

Global systolic left ventricular (LV) myocardial function progressively declines as degenerative aortic valve stenosis (AS) progresses. Whether this results in uniformly distributed deformation changes from base to apex has not been investigated.

METHODS

Eighty-five AS patients underwent three-dimensional (3D) echocardiography in this cross-sectional study. Patients were grouped by peak jet velocity into mild (n = 32), moderate (n = 31), and severe (n = 22) AS. 3D speckle tracking derived strain, rotation, twist, and torsion were obtained to assess global LV function and myocardial function at the apical, mid, and basal levels.

RESULTS

Global longitudinal strain (GLS) was lower in patients with severe AS (-16.1 ± 2.4% in mild, -15.5 ± 2.5% in moderate, and -13.5 ± 3.0% in severe AS [all p < .01]). Peak basal and mid longitudinal strain (LS), basal rotation and twist from apical to basal level followed the same pattern, while peak apical LS was higher in moderate AS compared to severe AS (all p < .05). In multivariate analyses, lower GLS was particularly associated with male sex, higher body mass index and peak aortic jet velocity, lower basal LS with higher filling pressure (E/e') and LV mass, lower mid LS with higher RWT and presence of AS symptoms, and lower apical LS with male sex and higher systolic blood pressure, respectively (all p < .05).

CONCLUSION

Using 3D speckle tracking echocardiography reveals regional and global changes in LV mechanics in AS related to the severity of AS, LV remodeling and presence of cardiovascular risk factors.

Molecular Approaches and Echocardiographic Deformation Imaging in Detecting Myocardial Fibrosis

The pathological remodeling of myocardial tissue is the main cause of heart diseases. Several processes are involved in the onset of heart failure, and the comprehension of the mechanisms underlying the pathological phenotype deserves special attention to find novel procedures to identify the site of injury and develop novel strategies, as well as molecular druggable pathways, to counteract the high degree of morbidity associated with it. Myocardial fibrosis (MF) is recognized as a critical trigger for disruption of heart functionality due to the excessive accumulation of extracellular matrix proteins, in response to an injury. Its diagnosis remains focalized on invasive techniques, such as endomyocardial biopsy (EMB), or may be noninvasively detected by cardiac magnetic resonance imaging (CMRI). The detection of MF by non-canonical markers remains a challenge in clinical practice. During the last two decades, two-dimensional (2D) speckle tracking echocardiography (STE) has emerged as a new non-invasive imaging modality, able to detect myocardial tissue abnormalities without specifying the causes of the underlying histopathological changes. In this review, we highlighted the clinical utility of 2D-STE deformation imaging for tissue characterization, and its main technical limitations and criticisms. Moreover, we focalized on the importance of coupling 2D-STE examination with the molecular approaches in the clinical decision-making processes, in particular when the 2D-STE does not reflect myocardial dysfunction directly. We also attempted to examine the roles of epigenetic markers of MF and hypothesized microRNA-based mechanisms aiming to understand how they match with the clinical utility of echocardiographic deformation imaging for tissue characterization and MF assessment.

Cardiac Fibrosis Is a Risk Factor for Severe COVID-19

Increased left ventricular fibrosis has been reported in patients hospitalized with coronavirus disease 2019 (COVID-19). It is unclear whether this fibrosis is a consequence of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection or a risk factor for severe disease progression. We observed increased fibrosis in the left ventricular myocardium of deceased COVID-19 patients, compared with matched controls. We also detected increased mRNA levels of soluble interleukin-1 receptor-like 1 (sIL1-RL1) and transforming growth factor β1 (TGF-β1) in the left ventricular myocardium of deceased COVID-19 patients. Biochemical analysis of blood sampled from patients admitted to the emergency department (ED) with COVID-19 revealed highly elevated levels of TGF-β1 mRNA in these patients compared to controls. Left ventricular strain measured by echocardiography as a marker of pre-existing cardiac fibrosis correlated strongly with blood TGF-β1 mRNA levels and predicted disease severity in COVID-19 patients. In the left ventricular myocardium and lungs of COVID-19 patients, we found increased neuropilin-1 (NRP-1) RNA levels, which correlated strongly with the prevalence of pulmonary SARS-CoV-2 nucleocapsid. Cardiac and pulmonary fibrosis may therefore predispose these patients to increased cellular viral entry in the lung, which may explain the worse clinical outcome observed in our cohort. Our study demonstrates that patients at risk of clinical deterioration can be identified early by echocardiographic strain analysis and quantification of blood TGF-β1 mRNA performed at the time of first medical contact.

Obesity-related ventricular remodelling is exacerbated in dilated and hypertrophic cardiomyopathy

Background

Obesity causes significant cardiac remodelling even in health, and yet the contribution of this maladaptation in the setting of an additional cardiomyopathic process is poorly understood. Cardiovascular magnetic resonance is the gold-standard tool for assessing cardiac geometry, especially in an obese population, and hence perfectly suited to investigate this important question.

Methods

Using data from our extensive imaging registry (n=1,554), we documented the relationship between increasing BMI and left ventricular (LV) remodelling in patients with dilated (DCM; n=529) and hypertrophic cardiomyopathy (HCM; n=297), compared to the normal heart (n=728).

Results

Regardless of cardiac status, increasing BMI resulted in similar increases in LV stroke volume (P>0.18). However, there was a difference in the degree of LV cavity dilatation associated with this change in stroke volume; when compared to normal hearts [increase in end-diastolic volume of 0.7 mL per unit of rising BMI (mL/kg/m²)], there was a threefold greater LV cavity dilatation in DCM (+2.2 mL/kg/m²) and twofold greater in HCM (+1.9 mL/kg/m², all P<0.04). Whilst obesity was related to LV hypertrophy in all groups (normal +1.3 g, DCM +2.2g, HCM +2.3 g/kg/m², all P<0.001), additional obesity-related concentric LV remodelling only occurred in normal hearts and DCM (normal +0.006 vs. +0.003 mass:volume ratio, both P<0.001).

Conclusions

In both DCM and HCM, the increase in stroke volume required by obesity appears to be achieved by excessive LV cavity dilatation. The impact of obesity on LV geometry was more pronounced in concomitant cardiovascular disease, and therefore carries potential to become an important therapeutic target in cardiomyopathy.

Myocardial tissue characterisation using echocardiographic deformation imaging

Myocardial pathology results in significant morbidity and mortality, whether due to primary cardiomyopathic processes or secondary to other conditions such as ischemic heart disease. Cardiac imaging techniques characterise the underlying tissue directly, by assessing a signal from the tissue itself, or indirectly, by inferring tissue characteristics from global or regional function. Cardiac magnetic resonance imaging is currently the most investigated imaging modality for tissue characterisation, but, due to its accessibility, advanced echocardiography represents an attractive alternative. Speckle tracking echocardiography (STE) is a reproducible technique used to assess myocardial deformation at both segmental and global levels. Since distinct myocardial pathologies affect deformation differently, information about the underlying tissue can be inferred by STE. In this review, the current available studies correlating STE deformation parameters with underlying tissue characteristics in humans are examined, with separate emphasis on global and segmental analysis. The current knowledge is placed in the context of integrated backscatter and the future of echocardiographic based tissue characterisation is discussed. The use of these imaging techniques to more precisely phenotype myocardial pathology more precisely will allow the design of translational cardiac research studies and, potentially, tailored management strategies.

Late Gadolinium Enhancement Predicts Improvement in Global Longitudinal Strain after Aortic Valve Replacement in Aortic Stenosis

Myocardial fibrosis, as detected by late gadolinium enhancement (LGE) magnetic resonance imaging (MRI), is related to mortality after aortic valve replacement (AVR). This study aimed to determine whether LGEMRI predicts improvement in global longitudinal strain (GLS) after AVR in patients with severe aortic stenosis (AS). Twenty-nine patients with severe AS who were scheduled to undergo AVR were enrolled. Two-dimensional echocardiography and contrast-enhanced MRI were performed before AVR. GLS and LGEcore (g: > 5 SD of normal area), LGEgray (g: 2–5 SD), and LGEcore+gray (g) were measured. One year after AVR, GLS were examined by echocardiography to assess improvement in LV function. Preoperatively, GLS correlated with LGEcore (g) (r² = 0.14, p < 0.05), LGEgray (g) (r² = 0.32, p < 0.01) and LGEcore+gray (g) (r² = 0.36, p < 0.01). LGEcore was significantly lower in patients with improved GLS after AVR (GLS_1year ≥ −19.9%) compared to those with no improvement (1.34 g vs. 4.70 g, p < 0.01). LGE predicts improvement in LV systolic function after AVR.

Impact of Obesity on Persistent Left Ventricular Hypertrophy After Aortic Valve Replacement for Aortic Stenosis

Normalization of left ventricular (LV) hypertrophy is expected after successful aortic valve replacement (AVR) in patients with aortic valve stenosis (AS), but is not always observed. We tested the impact of body mass index (BMI) ≥30 kg/m² on persistent post-AVR LV hypertrophy. In the present subanalysis of Simvastatin Ezetimibe in Aortic Stenosis study, clinical and echocardiographic data of 399 patients with severe AS who underwent surgical AVR were analyzed. All patients had a standardized pre- and post-AVR echocardiogram. Patients were grouped by BMI categories into BMI <25 kg/m², BMI 25 to 29.9 kg/m², and BMI ≥30 kg/m². LV hypertrophy was defined as LV mass/height^2.7 >49.2 g/m^2.7 in men and >46.7 g/m^2.7 in women. Predictors of persistent LV hypertrophy after AVR were identified in logistic regression analysis. After a median follow-up of 196 days after AVR, LV hypertrophy was more prevalent in patients with BMI ≥30 kg/m² compared with those with BMI 25 to 29.9 kg/m² and those patients with BMI <25 kg/m² (71% vs 47% and 37%, p <0.01). BMI ≥30 kg/m² patients also remained with lower LV midwall shortening post-AVR compared with patients with normal weight (p <0.01), independent of patient prosthesis mismatch. In multivariable logistic regression analysis, the presence of BMI ≥30 kg/m² before AVR was associated with an almost fourfold higher prevalence of post-AVR LV hypertrophy independent of significant associations with higher systolic blood pressure and lower LV midwall shortening preoperatively (odds ratio 3.75 [95% confidence interval 2.04 to 6.91], p <0.001). In conclusion, the presence of BMI ≥30 kg/m² before AVR in patients with severe AS was strongly and independently associated with persistent post-AVR LV hypertrophy.

Long-term Survival in Korean Elderly Patients with Symptomatic Severe Aortic Stenosis Who Refused Aortic Valve Replacement

BACKGROUND AND OBJECTIVES

Aortic valve replacement (AVR) is the treatment of choice in severe symptomatic aortic stenosis (AS) patients. However, a substantial number of elderly patients refuse AVR and treated medically. We investigated their long-term prognosis.

METHODS

From January 2005 to December 2016, we analyzed elderly patients with severe symptomatic AS who refused to have AVR.

RESULTS

After screening of total 534 patients, we analyzed total 180 severe symptomatic AS patients (78±7 years old, 96 males). Hypertension was the most common cardiovascular risk factor (72%) and the most common symptom was dyspnea (66%). Calculated aortic stenosis area was 0.73±0.20 cm² and mean left ventricular ejection fraction (LVEF) was 57.8±12.2%. Total 102 patients died during follow-up period (39.1±31.0 months). One-, 3-, and 5-year all-cause mortality rate was 21.1±3.0%, 43.1±3.8%, and 56.5±4.2%, respectively. Of them, 87 died from cardiac causes, and 1-, 3-, and 5-year cardiac mortality rate was 18.0±2.9%, 38.2±3.8%, and 50.7±4.3%, respectively. Their all-cause mortality and cardiac mortality were significantly higher than those of controls. Univariate analysis showed that age, anemia, LVEF, and Log N-terminal pro B-type natriuretic peptide (NT-proBNP) were significant parameters in all-cause mortality (p<0.001, p=0.001, p=0.039, and p=0.047, respectively) and in cardiac mortality (p<0.001, p<0.001, p=0.046, and p=0.026, respectively). Multivariate analysis showed that age and anemia were significant prognostic factors for cardiac and all-cause mortality.

CONCLUSIONS

In elderly severe symptomatic AS patients who treated medically, their 1-, 3- and 5-year all-cause mortality rate was 21.1±3.0%, 43.1±3.8%, and 56.5±4.2%, respectively. Age and anemia were significant prognostic factors for cardiac and all-cause mortality.