Left Atrial Phasic Volumes Are Modulated by the Type Rather Than the Extent of Left Ventricular Hypertrophy

Left Atrial Strain and Function in Pediatric Hypertrophic Cardiomyopathy

BACKGROUND

Left atrial (LA) strain and dysfunction are early markers of diastolic dysfunction, associated with poor exercise capacity in adults with hypertrophic cardiomyopathy (HCM). Literature on assessment of LA mechanics in pediatric HCM is lacking. The aim of this study was to assess LA strain and LA function in pediatric patients who have HCM with (phenotype positive [P+]) and without (genotype positive, phenotype negative [G+P-]) ventricular hypertrophy and evaluate their correlation with exercise stress test parameters.

METHODS

Seventy-eight children (3-25 years of age) with HCM (P+, n = 46; G+P-, n = 32) and 20 healthy control subjects were retrospectively studied. LA conduit function, reservoir function, and pump function were computed using phasic LA volumetric analysis. LA reservoir strain (LASr) and LA contractile strain were measured using speckle-tracking echocardiography. Exercise test findings within 12 months of echocardiography were recorded.

RESULTS

LA conduit function (36% vs 48%, P < .001) and LA reservoir function (137% vs 180%, P < .001) were lower in P+ than in G+P- patients. LA contractile function did not differ between the groups (31% vs 32%, P = .87). Compared with patients with G+P- HCM, those with P+HCM had lower four-chamber LASr (29% vs 41%, P < .001), two-chamber LASr (30% vs 41%, P < .001), average LASr (29% vs 42%, P < .001), and LA contractile strain (9% vs 12%, P = .016). In the cohort of patients with HCM who underwent stress testing (n = 35), LA conduit function weakly correlated with aerobic capacity (r = 0.42, P = .019).

CONCLUSIONS

Children with P+HCM have reduced LA function, measurable by both volumetric and strain analysis. Altered LA mechanics are associated with poor exercise capacity. This study lays the foundation for the evaluation of novel LA parameters in pediatric HCM and warrants larger longitudinal studies to assess its clinical significance.

Diagnostic value of left atrial strain in pediatric hypertrophic cardiomyopathy with normal maximum left atrial volume index: preliminary cardiac magnetic resonance study

BACKGROUND

The maximum left atrial volume index is the most widely used metric for assessing the left atrium in hypertrophic cardiomyopathy; however, it may be normal in the early phases of the disease.

OBJECTIVE

To assess whether pediatric hypertrophic cardiomyopathy patients with normal maximum left atrial volume index have impaired atrial functions on cardiac magnetic resonance imaging (MRI).

MATERIALS AND METHOD

A total of 26 pediatric hypertrophic cardiomyopathy patients and 24 age-matched children, as controls, were enrolled in the study. The left atrial reservoir, conduit and booster strain were calculated from two orthogonal planes and the left atrial volumes were calculated using the biplanar method. The extent of left ventricular late gadolinium enhancement (LGE-%) was calculated using the thresholding method. The left ventricular early diastolic longitudinal strain rate was calculated to assess diastolic dysfunction.

RESULTS

The maximum left atrial volume index of the children with hypertrophic cardiomyopathy and the controls were not significantly different (P>0.05). Most of the left atrial functional indices were worse in children with hypertrophic cardiomyopathy (P<0.05), yet no difference was observed between the left atrial booster strains of the two groups (P>0.05). The left atrial conduit strain showed moderate to good negative correlations with left ventricular LGE-% and diastolic dysfunction.

CONCLUSION

Left atrial conduit and reservoir strains are impaired in pediatric hypertrophic cardiomyopathy patients with normal maximum left atrial volumetric indices. Most left atrial strain parameters are closely linked to left ventricular LGE-% and diastolic dysfunction. Left atrial strain analysis may reveal subtle functional changes in the atrium before the increase in the maximum volume index.

The Indices of Cardiovascular Magnetic Resonance Derived Atrial Dynamics May Improve the Contemporary Risk Stratification Algorithms in Children with Hypertrophic Cardiomyopathy

Introduction: The most efficient risk stratification algorithms are expected to deliver robust and indefectible identification of high-risk children with hypertrophic cardiomyopathy (HCM). Here we compare algorithms for risk stratification in primary prevention in HCM children and investigate whether novel indices of biatrial performance improve these algorithms. Methods and Results: The endpoints were defined as sudden cardiac death, resuscitated cardiac arrest, or appropriate implantable cardioverter-defibrillator discharge. We examined the prognostic utility of classic American College of Cardiology/American Heart Association (ACC/AHA) risk factors, the novel HCM Risk-Kids score and the combination of these with indices of biatrial dynamics. The study consisted of 55 HCM children (mean age 12.5 ± 4.6 years, 69.1% males); seven had endpoints (four deaths, three appropriate ICD discharges). A strong trend (DeLong p = 0.08) was observed towards better endpoint identification performance of the HCM Risk-Kids Model compared to the ACC/AHA strategy. Adding the atrial conduit function component significantly improved the prediction capabilities of the AHA/ACC Model (DeLong p = 0.01) and HCM Risk-Kids algorithm (DeLong p = 0.04). Conclusions: The new HCM Risk-Kids individualised algorithm and score was capable of identifying high-risk children with very good accuracy. The inclusion of one of the atrial dynamic indices improved both risk stratification strategies.

Quantification of left atrial function in patients with non-obstructive hypertrophic cardiomyopathy by cardiovascular magnetic resonance feature tracking imaging: a feasibility and reproducibility study

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia in hypertrophic cardiomyopathy (HCM) and is associated with adverse outcomes in HCM patients. Although the left atrial (LA) diameter has consistently been identified as a strong predictor of AF in HCM patients, the relationship between LA dysfunction and AF still remains unclear. The aim of this study is to evaluate the LA function in patients with non-obstructive HCM (NOHCM) utilizing cardiovascular magnetic resonance feature tracking (CMR-FT).

METHODS

Thirty-three patients with NOHCM and 28 healthy controls were studied. The global and regional LA function and left ventricular (LV) function were compared between the two groups. The following LA global functional parameters were quantitively analyzed: reservoir function (total ejection fraction [LA total EF], total strain [εs], peak positive strain rate [SRs]), conduit function (passive ejection fraction [LA passive EF], passive strain [εe], peak early-negative SR [SRe]), and booster pump function (active ejection fraction [LA active EF], active strain [εa], peak late-negative SR [SRa]). The LA wall was automatically divided into 6 segments: anterior, antero-roof, inferior, septal, septal-roof and lateral. Three LA strain parameters (εs, εe, εa) and their corresponding strain rate parameters (SRs, SRe, SRa) during the reservoir, conduit and booster pump LA phases were segmentally measured and analyzed.

RESULTS

The LA reservoir (LA total EF: 57.6 ± 8.2% vs. 63.9 ± 6.4%, p < 0.01; εs: 35.0 ± 12.0% vs. 41.5 ± 11.2%, p = 0.03; SRs: 1.3 ± 0.4 s- 1 vs. 1.5 ± 0.4 s- 1, p = 0.02) and conduit function (LA passive EF: 28.7 ± 9.1% vs. 37.1 ± 10.0%, p < 0.01; εe: 18.7 ± 7.9% vs. 25.9 ± 10.0%, p < 0.01; SRe: - 0.8 ± 0.3 s- 1 vs. -1.1 ± 0.4 s- 1, p < 0.01) were all impaired in patients with NOHCM when compared with healthy controls, while LA booster pump function was preserved. The LA segmental strain and strain rate analysis demonstrated that the εs, εe, SRe of inferior, SRs, SRe of septal-roof, and SRa of antero-roof walls (all p < 0.05) were all decreased in the NOHCM cohort. Correlations between LA functional parameters and LV conventional function and LA functional parameters and baseline parameters (age, body surface area and NYHA classification) were weak. The two strongest relations were between εs and LA total EF(r = 0.84, p < 0.01), εa and LA active EF (r = 0.83, p < 0.01).

CONCLUSIONS

Compared with healthy controls, patients with NOHCM have LA reservoir and conduit dysfunction, and regional LA deformation before LA enlargement. CMR-FT identifies LA dysfunction and deformation at an early stage.

Biatrial performance in children with hypertrophic cardiomyopathy: CMR study

OBJECTIVES

To investigate biatrial mechanics and their relation with left ventricular outflow tract (LVOT) obstruction (LVOTO), the degree of hypertrophy, indices of ventricular diastolic function and fibrosis in children with hypertrophic cardiomyopathy (HCM).

METHODS

Fifty-five consecutive, prospectively recruited children with HCM (mean age 12.5 ± 4.6 years, 69.1% male), 19 (34.5%) of whom had LVOTO, underwent cardiac magnetic resonance and echocardiography with quantification of phasic components of biatrial function, biventricular diastolic function and fibrosis. Twenty healthy, sex-matched subjects served as controls.

RESULTS

We found a significant increase of left atrial (LA) and right atrial (RA) volumes and reduction in the majority of indices of contractile function, strains and strain rates (p < 0.05) in children with HCM compared with controls. Nearly all of the LA dynamics markers attained a significant association with the LVOT gradient (p < 0.05), the RA volumes and contractile functions were affected by LV fibrosis and mass (p < 0.05), and the RA mechanical components were related to the degree of LVOTO (p < 0.05). The minority of biatrial dynamics markers were associated with indices of ventricular diastolic function.

CONCLUSIONS

The majority of biatrial volumetric and functional indices were severely compromised in children with HCM compared with controls. The degree of LVOTO appears to trigger LA volumetric and LA and RA mechanical malfunction. On the other hand, the deterioration of RA volumetric components was linked to LV fibrosis and mass.

KEY POINTS

• Biatrial function was severely compromised in children with HCM. • Left atrial malfunction was associated with the degree of LVOTO. • Fibrosis and LV mass were related to RA volumetric and contractile dysfunction. • The degree of LVOTO was linked to right atrial mechanical abnormalities.

Right Atrial Evaluation in Patients With Pulmonary Hypertension: A Real-time 3-Dimensional Transthoracic Echocardiographic Study

OBJECTIVES

The purpose of this study was to investigate the changes in the morphologic characteristics and performance of the right atrium (RA) that occur secondary to structural remodeling of the right ventricle (RV) in patients with pulmonary hypertension by real-time 3-dimensional echocardiography (3DE).

METHODS

Comprehensive 2-dimensional echocardiography and real-time 3DE were performed in 112 patients and 30 healthy control participants. Patients with pulmonary hypertension were divided into 3 subgroups: 1, normal RV dimension (n = 34); 2, RV enlargement and preserved systolic function (n = 36); and 3, RV enlargement and systolic dysfunction (n = 42).

RESULTS

Patients had larger RA volume parameters and lower RA passive emptying fractions than controls (P< .01). The RA active emptying fraction was higher in patient groups 1 (mean ± SD, 45.5% ± 10.7%) and 2 (40.1% ± 4.0%) and lower in group 3 (19.3% ± 4.3%) compared to controls (35.4% ± 3.5%). The RA total emptying fraction was similar between groups 1 and 2 (59.3% ± 9.7% and 52.6% ± 3.4%, respectively) but was significantly lower in group 3 compared to controls (26.8% ± 5.1% versus 55.2% ± 5.1%). Right atrial volume and phasic function were substantially affected by RV structure and function.

CONCLUSIONS

Real-time 3DE is a feasible, repeatable, and noninvasive method for accessing cyclic RA volume and function changes, such as those that occur with varying RV status in patients with pulmonary hypertension.

The role of imaging in the diagnosis and management of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiomyopathy, affecting approximately 1:500 people. As the yield of genetic testing is only about 35-60%, the diagnosis of HCM is still clinical and based on the demonstration of unexplained and usually asymmetric left ventricular (LV) hypertrophy by imaging modalities. In the past, echocardiography was the sole imaging modality used for the diagnosis and management of HCM. However, in recent years other imaging modalities such as cardiac magnetic resonance have played a major role in the diagnosis, management and risk stratification of HCM, particularly when the location of left ventricular hypertrophy is atypical (apex, lateral wall) and when the echocardiographic imaging is sub-optimal. However, the most unique contribution of cardiac magnetic resonance is the quantification of myocardial fibrosis. Exercise stress echocardiography is the preferred provocative test for the assessment of LV outflow tract obstruction, which is detected only on provocation in one-third of the patients.

How to identify hypertensive patients at high cardiovascular risk? The role of echocardiography

Scientific authorities recommend that patients with arterial hypertension should be managed not only on the basis of blood pressure (BP) levels, but also on the assemement of total cardiovascular risk. In particular, evaluation of target organ damage (TOD) is of major relevance for identifying hypertensive individuals at high cardiovascular risk independently of clinic BP levels. Evidence of cardiac and extra-cardiac TOD has been consistently associated with worse cardiovascular prognosis. Unfortunately, detection of TOD markedly depends on sensitivity of diagnostic tools, at difference from evaluation of risk factors and associated diseases, usually reliably provided by accurate clinical examination and routine investigation. The purpose of this paper was to provide an updated, comprehensive review on the role of echocardiography in identifying hypertensive patients apparently uncomplicated, but exposed to a high cardiovascular risk due to the presence of subclinical structural and functional cardiac alterations of adverse prognostic significance.

Normal left-atrial structure and function despite concentric left-ventricular remodelling in a cohort of patients with Anderson-Fabry disease

AIMS

Anderson-Fabry Disease (AFD) is an important cause of cardiomyopathy characterized by concentric left-ventricular hypertrophy (LVH). We evaluated the extent of left-atrial (LA) structural and functional remodelling in this group of patients given that LA remodelling is a marker of adverse outcomes in the presence of LVH.

METHODS AND RESULTS

Clinical profiles were obtained and cardiac MRI was performed in cohorts of patients with AFD (n = 31), healthy controls (n = 23), and a positive control cohort with known concentric remodelling and LVH (CR/H, n = 21). Of patients with AFD, 58% were on enzyme-replacement therapy (ERT), 84% were on renin-angiotensin system antagonism, and 65% were on statins. Despite a similar increase in LV mass index in the AFD when compared with the CR/H cohort, mean LA volumes for the AFD group were similar to those seen in the healthy control group. Following from this, we observed that the percentage contribution to LV stroke volume due to elastic/passive and active LA emptying was similar in the AFD and healthy control groups, while passive emptying was significantly lower in the CR/H group. The consequences of LVH in the AFD cohort were manifested in atrioventricular uncoupling, whereby the extent of elastic/passive and active LA emptying was not a function of the extent of longitudinal movement of the mitral annular plane, as it was in healthy control subjects.

CONCLUSION

Left-atrial structure and function were relatively normal in our cohort of patients with AFD, who were also judiciously treated with a contemporary strategy that includes renin-angiotensin system antagonism, statins, and ERT.

Left ventricular and atrial functions in hypertrophic cardiomyopathy patients with very high LVOT gradient: a speckle tracking echocardiographic study

BACKGROUND

Determination of myocardial deformation (strain) by two-dimensional (2D) speckle tracking echocardiography (STE) is a new method for evaluating left ventricular (LV) regional function in patients with hypertrophic cardiomyopathy (HCM). The aim of this study was to assess LV and left atrial (LA) functions with 2DSTE in HCM patients and to investigate relation between strain analysis and LV outflow tract (LVOT) gradient.

METHODS

Forty consecutive HCM patients (26 male, mean age: 47.7 ± 15.2 years), and 40 healthy volunteers (22 male, mean age: 46.6 ± 11.2 years) were included in the study. All subjects underwent a transthoracic echocardiography for evaluation of LV and LA functions with 2DSTE. The HCM patients were divided into 2 groups according to the presence of resting LVOT gradient >100 mmHg.

RESULTS

Left ventricular global longitudinal strain (GLS), global radial strain (GRS), and global circumferential strain (GCS) were significantly lower in patients with HCM compared with controls (-20.3 ± 3.6% vs. -24.1 ± 3.4% P < 0.001, 38.1 ± 12.8% vs. 44.8 ± 10.2% P = 0.012, and -22.0 ± 4.4% vs. -23.9 ± 4.0% P = 0.045, respectively). Although basal and apical rotation were similar between the groups, mid-rotation was significantly clockwise in HCM patients (-1.53 ± 2.06° vs. 0.05 ± 1.7° P < 0.001). Both LA reservoir functions and LA conduit functions were significantly lower in HCM patients (21.6 ± 9.1% vs. 39.4 ± 10.6% P < 0.001, and 10.5 ± 4.3% vs. 15.7 ± 5.3%, P < 0.001). Fifteen patients had a resting LVOT gradient of >100 mmHg and they had significantly decreased GLS, twist and untwist compared to the HCM patients with lower resting LVOT gradient (-18.7 ± 2.3% vs. -21.2 ± 3.9% P = 0.016, 19.4 ± 4.3° vs. 23.5 ± 7.4° P = 0.038 and -94.0 ± 29.1°/sec vs. -134.9 ± 55.8°/sec, 0.005, respectively). Although basal and apical rotation were similar between the 2 groups, mid-rotation was significantly clockwise in HCM patients with higher LVOT gradient (-2.52 ± 1.76° vs. -0.96 ± 2.03°, P = 0.018). Correlation analysis revealed that LVOT peak velocity was associated with GLS (r = -0.358, P = 0.023), LV mid-rotation (r = -0.366, P = 0.024), and LV untwist (r = -0.401, P = 0.013).

CONCLUSIONS

Left ventricular and LA functions are impaired in patients with HCM. 2DSTE is useful in determining patients with impaired myocardial mechanics. High LVOT gradient may be one of the responsible factors that trigger deterioration of LV longitudinal strain and twist mechanics in patients with HCM. Further studies are required to clarify the preliminary results of this study.