Diastolic abnormalities in normal phenotype hypertrophic cardiomyopathy gene carriers: a study using speckle tracking echocardiography

Assessment of left atrial myocardial deformation using two-dimensional speckle-tracking echocardiography in cats with cardiogenic and non-cardiogenic arterial thromboembolism

Arterial thromboembolism (ATE) in cats usually relates to cardiogenic causes that can be diagnosed by conventional echocardiography. Two-dimensional speckle-tracking echocardiography (2D-STE) is a new ultrasound modality with higher sensitivity. Our objective was to investigate left atrial myocardial deformation in cats with both cardiogenic and non-cardiogenic ATE and normal cats using 2D-STE. Twenty-three normal cats and 21 cats with ATE cats were recruited and performed conventional echocardiography and 2D-STE. From the results, left atrial (LA) strain and strain rate from 2D-STE were significantly decreased in cats with cardiogenic ATE (P < 0.001), but there was no significant difference in non-cardiogenic ATE compared with normal cats. From the correlation test, the use of left atrial strain during the reservoir phase (LASr) could represent the overall LA deformation. The intra- and inter-observer coefficient of variation of LASr was less than 15%. The logistic regression revealed that the LASr value of less than 11% was a significant factor for the occurrence of ATE (odd ratio = 189.0, P < 0.001). In conclusion, LASr derived by 2D-STE is a repeatable and non-invasive technique to assess LA myocardial deformation in cats with ATE. By 2D-STE, impaired LA function was detected in cats with cardiogenic ATE. LASr < 11% may use as a predictor of the risk of ATE occurrence in cats.

Five-year prognostic significance of global longitudinal strain in individuals with a hypertrophic cardiomyopathy gene mutation without hypertrophic changes

Background

Previous studies have reported that global longitudinal strain (GLS) is reduced in patients with hypertrophic cardiomyopathy (HCM) while left ventricular ejection fraction (LVEF) is normal. Our aim was to assess GLS in individuals with HCM mutations without hypertrophic changes and to determine its prognostic value for the development of HCM.

Methods and results

This retrospective case-control and cohort study included 120 HCM mutation carriers and 110 controls. GLS and LVEF were assessed with Tomtec Imaging software. Age, gender, and body surface area were similar in mutation carriers and controls. Compared to controls, mutation carriers had a higher maximal wall thickness (9 ± 2 vs 8 ± 2 mm, p < 0.001), higher LVEF (60 ± 5 vs 58 ± 4%, p < 0.001) and higher GLS (−21.4 ± 2.3% vs −20.3 ± 2.2%, p < 0.001). The GLS difference was observed in the mid-left ventricle (−21.5 ± 2.5% vs −19.9 ± 2.5%, p < 0.001) and the apex (−24.1 ± 3.5% vs −22.1 ± 3.4%, p < 0.001), but not in the base of the left ventricle (−20.0 ± 3.3% vs −20.0 ± 2.6%, p = 0.9). Echocardiographic follow-up was performed in 80 mutation carriers. During 5.6 ± 2.9 years’ follow-up, 13 (16%) mutation carriers developed HCM. Cox regression analysis showed age (hazard ratio (HR) 1.08, p = 0.01), pathological Q wave (HR 8.56; p = 0.01), and maximal wall thickness (HR 1.94; p = 0.01) to be independent predictors of the development of HCM. GLS was not predictive of the development of HCM (HR 0.78, p = 0.07).

Conclusion

GLS is increased in HCM mutation carriers without hypertrophic changes. GLS was of no clear prognostic value for the development of HCM during follow-up, in contrast to age, pathological Q waves and maximal wall thickness.

Electronic supplementary material

The online version of this article (10.1007/s12471-019-1226-5) contains supplementary material, which is available to authorized users.

Prognostic significance of anterior mitral valve leaflet length in individuals with a hypertrophic cardiomyopathy gene mutation without hypertrophic changes

Purpose

Previous studies suggest that anterior mitral valve leaflet (AMVL) elongation is a primary phenotypic feature in hypertrophic cardiomyopathy (HCM). Our aim was to assess AMVL length in individuals with HCM gene mutations and in healthy controls and to identify predictors of the development of HCM during follow-up.

Methods

A total of 133 HCM mutation carriers and 135 controls underwent cardiac examination including electro- and echocardiography. AMVL length was measured in the parasternal long axis and apical three chamber view during diastole. Univariate and multivariable cox proportional hazard regression analyses were performed to identify predictors of HCM.

Results

There were no significant differences between HCM mutation carriers and controls regarding age and sex. In the parasternal long axis view, AMVL length was similar in mutation carriers and controls (24 ± 4 vs 24 ± 4 mm, p = 0.8). In the apical three chamber view, AMVL were shorter in mutation carriers (29 ± 4 vs 30 ± 4 mm, p = 0.02). When averaged for both views, AMVL length was similar in mutation carriers and controls (27 ± 3 vs 27 ± 3 mm, p = 0.2). During 5.8 ± 3.0 years follow-up, 13 (14%) HCM mutation carriers developed HCM. Pathological Q wave (hazard ratio 9.89, p = 0.004), E/e′ ratio (hazard ratio 2.52, p = 0.001), and maximal wall thickness (hazard ratio 2.15, p = 0.001) were independent predictors of HCM. AMVL length was not predictive of the development of HCM.

Conclusions

AMVL length is similar in HCM mutation carriers and controls. AMVL length is not predictive of the development of HCM, in contrast to pathological Q wave, E/e′ ratio, and maximal wall thickness.

Left ventricular short-axis systolic function changes in patients with hypertrophic cardiomyopathy detected by two-dimensional speckle tracking imaging

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a genetic disease was characterised by left ventricular hypertrophy (LVH), myocardial fibrosis, fiber disarray. The short-axis systolic function is important in left ventricle function.

METHODS

Forty one healthy subjects and 37 HCM patients were enrolled for this research. Parasternal short-axis at the basal, middle, and apical levels were acquired by Echocardiography. The peak systolic circumferential strain of the endocardial, the middle and the epicardial layers, the peak systolic radial strain, and the peak systolic rotational degrees at different short-axis levels were measured by 2-dimensional speckle tracking imaging (2D-STI).

RESULTS

The peak systolic circumferential strain of the septum and anterior walls in HCM patients was significantly lower than normal subjects. All of the peak systolic radial strain in HCM patients was significantly lower than normal subjects. The rotational degrees at the base and middle short-axis levels in HCM patients were larger than normal subjects. The interventricular septal thickness in end-diastolic period correlated to the peak systolic circumferential strain of the septum wall.

CONCLUSIONS

The short-axis systolic function was impaired in HCM patients. The peak circumferential systolic strain of the different layers, peak systolic radial strain and rotation degrees of the different short-axis levels detected by 2D-STI are very feasible for assessing the short-axis function in HCM patients.

Diastolic Dysfunction of Hypertrophic Cardiomyopathy Genotype-Positive Subjects Without Hypertrophy Is Detected by Tissue Doppler Imaging: A Systematic Review and Meta-analysis

OBJECTIVES

To evaluate whether diastolic dysfunction derived by tissue Doppler imaging (TDI) would be an earlier manifestation in genotype-positive hypertrophic cardiomyopathy (HCM) subjects without left ventricular hypertrophy (LVH).

METHODS

We systematically searched Pubmed, Medline, and Web of Science with an upper date limit of June 2016 for studies evaluating the diastolic function of HCM genotype-positive subjects without hypertrophy (G+/LVH-). Based on the inclusion criteria, eligible studies were selected. The quality of selected studies was assessed by the Newcastle-Ottawa Scale before being included in the meta-analysis. The statistic data such as weighted mean difference (WMD) and 95% confidence interval (CI) were calculated by Stata 12.0 software.

RESULTS

Seventeen studies were included in the systematic review, and 12 were finally involved in the meta-analysis. The G+/LVH- subjects showed decreased Ea derived by TDI on both the interventricular septum (WMD [95% CI] = -1.822 [-3.104, -0.541]) and lateral wall (WMD [95% CI] = -2.269 [-3.820, -0.719]), and increased E/Ea on both interventricular septum (WMD [95% CI] = 1.363 [0.552, 2.174]) and lateral (WMD [95% CI] = 1.339 [0.386, 2.293]) wall.

CONCLUSIONS

Tissue Doppler imaging-derived diastolic dysfunction can be found in HCM genotype-positive subjects without hypertrophy.

Left ventricular systolic function changes in hypertrophic cardiomyopathy patients detected by the strain of different myocardium layers and longitudinal rotation

BACKGROUND

Impairment of left ventricular (LV) longitudinal function has an important role in hypertrophic cardiomyopathy (HCM). This research investigated an association between the longitudinal strain of different myocardial layers, longitudinal rotation and the LV systolic function of HCM patients.

METHODS

The research was performed on 36 HCM patients and 36 healthy subjects. The peak systolic longitudinal strain of the subendocardial, midmyocardial, and subepicardial layers was measured using 2-dimensional speckle tracking echocardiography (2D-STE). The apical long-axis and 4- and 2- chamber views were acquired via 2D Doppler echocardiography. The curve of the longitudinal rotation was traced at 17 timepoints in the analysis of 2 cardiac cycles.

RESULTS

Compared with healthy subjects, in HCM patients regional LV peak systolic longitudinal strain was less, not only in hypertrophied LV myocardium, but also in non-hypertrophied myocardium. The rotational degrees of the midmyocardial-septal, apex, and lateral wall of HCM patients were significantly different from that of normal subjects, as follows. In HCM patients, clockwise longitudinal rotation was found. The interventricular septum thickness at end-diastole positively correlated with the peak longitudinal systolic strain of the subendocardial, the midmyocardial, and the subepicardial layers. The area under ROC curve values for subendocardial, midmyocardial and subepicardial layers in HCM patients were 0.923, 0.938, 0.948.

CONCLUSION

In HCM patients, the longitudinal function was damaged, even with normal LV ejection fraction. The peak longitudinal systolic strain of the subendocardial, midmyocardial, and subepicardial layers, and the longitudinal rotation detected by 2D-STE, are very sensitive predictors of systolic function in patients with HCM.

Delayed and decreased LV untwist and unstrain rate in mutation carriers for hypertrophic cardiomyopathy

Background

The echocardiographic focus to detect abnormalities in genetically hypertrophic cardiomyopathy (HCM) affected subjects without left ventricular (LV) hypertrophy (G+/LVH-) has been on diastolic abnormalities in transmitral flow and longitudinal myocardial function with tissue Doppler imaging. The aim of this study was to assess diastolic LV unstrain and untwist.

Methods and results

Forty-one consecutive genotyped family members of HCM patients (mean age 37 ± 11 years, 16 men) and 41 age- and gender-matched healthy volunteers underwent speckle-tracking echocardiography to measure untwist and unstrain. No significant differences between G+/LVH- and control subjects were seen in maximal systolic twist and global longitudinal strain. In diastole, the early peak untwist rate was significantly lower in G+/LVH- subjects compared with control subjects (62 ± 19°s - 1 vs. 76 ± 30°s - 1, P <0.05), whereas the late peak untwist rate tended to be higher. Untwist from maximal twist until the first 20% of diastole was delayed in G+/LVH- subjects (39.3 ± 12.9% vs. 51.3 ± 15.6%, P <0.005). Late diastolic unstrain rate was significantly higher in G+/LVH- subjects in the inferoseptal wall (111 ± 33 s - 1 vs. 94 ± 32 s - 1, P = 0.024), the inferolateral wall (105 ± 42 vs. 75 ± 35 s - 1, P = 0.007) and the anteroseptal wall (97 ± 26 vs. 80 ± 23 s - 1, P = 0.010). Unstrain from maximal twist until the first 20% of diastole was delayed in G+/LVH- subjects in the inferoseptal (18.9 ± 14.0% vs. 30.1 ± 17.7%, P = 0.005), inferolateral (27.1 ± 16.3% vs. 39.2 ± 18.0%, P = 0.015) and anteroseptal (19.1 ± 14.7% vs. 35.8 ± 18.5%, P = 0.0003) segments.

Conclusions

In mutation carriers, for HCM LV, untwist and unstrain are delayed and untwist rate and unstrain rate are decreased.

Update on hypertrophic cardiomyopathy and a guide to the guidelines

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiovascular disorder, affecting 1 in 500 individuals worldwide. Existing epidemiological studies might have underestimated the prevalence of HCM, however, owing to limited inclusion of individuals with early, incomplete phenotypic expression. Clinical manifestations of HCM include diastolic dysfunction, left ventricular outflow tract obstruction, ischaemia, atrial fibrillation, abnormal vascular responses and, in 5% of patients, progression to a 'burnt-out' phase characterized by systolic impairment. Disease-related mortality is most often attributable to sudden cardiac death, heart failure, and embolic stroke. The majority of individuals with HCM, however, have normal or near-normal life expectancy, owing in part to contemporary management strategies including family screening, risk stratification, thromboembolic prophylaxis, and implantation of cardioverter-defibrillators. The clinical guidelines for HCM issued by the ACC Foundation/AHA and the ESC facilitate evaluation and management of the disease. In this Review, we aim to assist clinicians in navigating the guidelines by highlighting important updates, current gaps in knowledge, differences in the recommendations, and challenges in implementing them, including aids and pitfalls in clinical and pathological evaluation. We also discuss the advances in genetics, imaging, and molecular research that will underpin future developments in diagnosis and therapy for HCM.

The embryological basis of subclinical hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is caused by mutations in sarcomeric proteins, the commonest being MYBPC3 encoding myosin-binding protein C. It is characterised by left ventricular hypertrophy but there is an important pre-hypertrophic phenotype with features including crypts, abnormal mitral leaflets and trabeculae. We investigated these during mouse cardiac development using high-resolution episcopic microscopy. In embryonic hearts from wildtype, homozygous (HO) and heterozygous (HET) Mybpc3-targeted knock-out (KO) mice we show that crypts (one or two) are a normal part of wildtype development but they almost all resolve by birth. By contrast, HO and HET embryos had increased crypt presence, abnormal mitral valve formation and alterations in the compaction process. In scarce normal human embryos, crypts were sometimes present. This study shows that features of the human pre-hypertrophic HCM phenotype occur in the mouse. In an animal model we demonstrate that there is an embryological HCM phenotype. Crypts are a normal part of cardiac development but, along with the mitral valve and trabeculae, their developmental trajectory is altered by the presence of HCM truncating Mybpc3 gene mutation.

Prediction of sarcomere mutations in subclinical hypertrophic cardiomyopathy

BACKGROUND

Sarcomere protein mutations in hypertrophic cardiomyopathy induce subtle cardiac structural changes before the development of left ventricular hypertrophy (LVH). We have proposed that myocardial crypts are part of this phenotype and independently associated with the presence of sarcomere gene mutations. We tested this hypothesis in genetic hypertrophic cardiomyopathy pre-LVH (genotype positive, LVH negative [G+LVH-]).

METHODS AND RESULTS

A multicenter case-control study investigated crypts and 22 other cardiovascular magnetic resonance parameters in subclinical hypertrophic cardiomyopathy to determine their strength of association with sarcomere gene mutation carriage. The G+LVH- sample (n=73) was 29 ± 13 years old and 51% were men. Crypts were related to the presence of sarcomere mutations (for ≥1 crypt, β=2.5; 95% confidence interval [CI], 0.5-4.4; P=0.014 and for ≥2 crypts, β=3.0; 95% CI, 0.8-7.9; P=0.004). In combination with 3 other parameters: anterior mitral valve leaflet elongation (β=2.1; 95% CI, 1.7-3.1; P<0.001), abnormal LV apical trabeculae (β=1.6; 95% CI, 0.8-2.5; P<0.001), and smaller LV end-systolic volumes (β=1.4; 95% CI, 0.5-2.3; P=0.001), multiple crypts indicated the presence of sarcomere gene mutations with 80% accuracy and an area under the curve of 0.85 (95% CI, 0.8-0.9). In this G+LVH- population, cardiac myosin-binding protein C mutation carriers had twice the prevalence of crypts when compared with the other combined mutations (47 versus 23%; odds ratio, 2.9; 95% CI, 1.1-7.9; P=0.045).

CONCLUSIONS

The subclinical hypertrophic cardiomyopathy phenotype measured by cardiovascular magnetic resonance in a multicenter environment and consisting of crypts (particularly multiple), anterior mitral valve leaflet elongation, abnormal trabeculae, and smaller LV systolic cavity is indicative of the presence of sarcomere gene mutations and highlights the need for further study.

Abnormal cardiac formation in hypertrophic cardiomyopathy: fractal analysis of trabeculae and preclinical gene expression

BACKGROUND

Mutations in genes coding for sarcomeric proteins cause hypertrophic cardiomyopathy. Subtle abnormalities of the myocardium may be present in mutation carriers without left ventricular hypertrophy (G+LVH-) but are difficult to quantify. Fractal analysis has been used to define trabeculae in left ventricular noncompaction and to identify normal racial variations. We hypothesized that trabeculae measured by fractal analysis of cardiovascular magnetic resonance images are abnormal in G+LVH- patients, providing a preclinical marker of disease in hypertrophic cardiomyopathy.

METHODS AND RESULTS

Cardiovascular magnetic resonance was performed on 40 G+LVH- patients (33±15 years, 38% men), 67 patients with a clinical diagnosis of hypertrophic cardiomyopathy (53±15 years, 76% men; 31 with a pathogenic mutation [G+LVH+]), and 69 matched healthy volunteers (44±15 years, 57% men). Trabeculae were quantified by fractal analysis of cine slices to calculate the fractal dimension, a unitless index of endocardial complexity calculated from endocardial contours after segmentation. In G+LVH- patients, apical left ventricular trabeculation was increased compared with controls (maximal apical fractal dimension, 1.249±0.07 versus 1.199±0.05; P=0.001). In G+LVH+ and G-LVH+ cohorts, maximal apical fractal dimension was greater than in controls (P<0.0001) irrespective of gene status (G+LVH+: 1.370±0.08; G-LVH+: 1.380±0.09). Compared with controls, G+LVH- patients also had a higher frequency of clefts (28% versus 8%; P=0.02), longer anterior mitral valve leaflets (23.5±3.0 versus 19.7±3.1 mm; P<0.0001), greater septal systolic wall thickness (12.6±3.2 versus 11.2±2.1 mm; P=0.03), higher ejection fraction (71±4% versus 69±4%; P=0.03), and smaller end-systolic volumes (38±9 versus 43±12 mL; P=0.03).

CONCLUSIONS

Increased myocardial trabecular complexity is one of several preclinical abnormalities in hypertrophic cardiomyopathy sarcomere gene mutation carriers without LVH.

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.