Subclinical echocardiographic abnormalities in phenotype-negative carriers of myosin-binding protein C3 gene mutation for hypertrophic cardiomyopathy

Methylation analysis by targeted bisulfite sequencing in large for gestational age (LGA) newborns: the LARGAN cohort

BACKGROUND

In 1990, David Barker proposed that prenatal nutrition is directly linked to adult cardiovascular disease. Since then, the relationship between adult cardiovascular risk, metabolic syndrome and birth weight has been widely documented. Here, we used the TruSeq Methyl Capture EPIC platform to compare the methylation patterns in cord blood from large for gestational age (LGA) vs adequate for gestational age (AGA) newborns from the LARGAN cohort.

RESULTS

We found 1672 differentially methylated CpGs (DMCs) with a nominal p < 0.05 and 48 differentially methylated regions (DMRs) with a corrected p < 0.05 between the LGA and AGA groups. A systems biology approach identified several biological processes significantly enriched with genes in association with DMCs with FDR < 0.05, including regulation of transcription, regulation of epinephrine secretion, norepinephrine biosynthesis, receptor transactivation, forebrain regionalization and several terms related to kidney and cardiovascular development. Gene ontology analysis of the genes in association with the 48 DMRs identified several significantly enriched biological processes related to kidney development, including mesonephric duct development and nephron tubule development. Furthermore, our dataset identified several DNA methylation markers enriched in gene networks involved in biological pathways and rare diseases of the cardiovascular system, kidneys, and metabolism.

CONCLUSIONS

Our study identified several DMCs/DMRs in association with fetal overgrowth. The use of cord blood as a material for the identification of DNA methylation biomarkers gives us the possibility to perform follow-up studies on the same patients as they grow. These studies will not only help us understand how the methylome responds to continuum postnatal growth but also link early alterations of the DNA methylome with later clinical markers of growth and metabolic fitness.

Predicting Development of Hypertrophic Cardiomyopathy and Disease Outcomes in Cats

Echocardiography is the gold standard imaging modality to diagnose hypertrophic cardiomyopathy (HCM) in cats. Echocardiographic features can predict both cats at an increased risk of developing HCM and cats with HCM at an increased risk of developing cardiovascular events or experiencing cardiac death. Left atrial dysfunction seems to be an important feature of HCM, as it is an early phenotypic abnormality and is also associated with worse outcome.

The «Amish» NM_000256.3:c.3330+2T>G splice variant in MYBPC3 associated with hypertrophic cardiomyopathy is an ancient Swiss mutation

MYBPC3 is the most frequently mutated gene in hypertrophic cardiomyopathy (HCM). Several loss-of-function founder variants have been reported in MYBPC3 from various geographic regions, altogether suggestive of a modest or absent effect of these variants on reproductive fitness. One of them, a MYBPC3 splice variant, NM_000256.3:c.3330+2T > G, was first described in homozygous state in newborns presenting with a severe, recessive form of HCM among the Amish population and was later associated with adult-onset dominant HCM in heterozygous carriers. We here report this splice variant in heterozygous state in eight unrelated Swiss families with HCM, making it the most prevalent cardiomyopathy variant in western Switzerland. This variant was identified in patients using targeted (n = 5) or full-genome sequencing (n = 3). Given the prevalence of this variant in the Old Order Amish, Mennonites and Swiss populations, and given that both Amish and Mennonites founders originated from the Bern Canton in Switzerland, the MYBPC3, NM_000256.3:c.3330+2T > G variant appears to be of Swiss origin. Neighboring regions that hosted the first Amish settlements (Alsace, South Germany) should be on the lookout for that variant. The existence of MYBPC3 founder variants in different populations suggests that individuals with early-onset clinical disease may be the tip of the iceberg of a much larger number of asymptomatic carriers. Alternatively, reproductive fitness could even be slightly increased in some variant carriers to compensate for the reduction of fitness in the more severely affected ones, but this remains to be investigated.

Critical Evaluation of Current Hypotheses for the Pathogenesis of Hypertrophic Cardiomyopathy

Hereditary hypertrophic cardiomyopathy (HCM), due to mutations in sarcomere proteins, occurs in more than 1/500 individuals and is the leading cause of sudden cardiac death in young people. The clinical course exhibits appreciable variability. However, typically, heart morphology and function are normal at birth, with pathological remodeling developing over years to decades, leading to a phenotype characterized by asymmetric ventricular hypertrophy, scattered fibrosis and myofibrillar/cellular disarray with ultimate mechanical heart failure and/or severe arrhythmias. The identity of the primary mutation-induced changes in sarcomere function and how they trigger debilitating remodeling are poorly understood. Support for the importance of mutation-induced hypercontractility, e.g., increased calcium sensitivity and/or increased power output, has been strengthened in recent years. However, other ideas that mutation-induced hypocontractility or non-uniformities with contractile instabilities, instead, constitute primary triggers cannot yet be discarded. Here, we review evidence for and criticism against the mentioned hypotheses. In this process, we find support for previous ideas that inefficient energy usage and a blunted Frank–Starling mechanism have central roles in pathogenesis, although presumably representing effects secondary to the primary mutation-induced changes. While first trying to reconcile apparently diverging evidence for the different hypotheses in one unified model, we also identify key remaining questions and suggest how experimental systems that are built around isolated primarily expressed proteins could be useful.

Echocardiographic Deformation Imaging for Early Detection of Genetic Cardiomyopathies: JACC Review Topic of the Week

Clinical screening of the relatives of patients with genetic cardiomyopathies is challenging, as they often lack detectable cardiac abnormalities at presentation. Life-threatening adverse events can already occur in these early stages of disease, so sensitive tools to reveal the earliest signs of disease are needed. The utility of echocardiographic deformation imaging for early detection has been explored for this population in multiple studies but has not been broadly implemented in clinical practice. The authors discuss contemporary evidence on the utility of deformation imaging in relatives of patients with genetic cardiomyopathies. The available body of data shows that deformation imaging reveals early disease-specific abnormalities in dilated cardiomyopathy, hypertrophic cardiomyopathy, and arrhythmogenic cardiomyopathy. Deformation imaging seems promising to enhance the screening and follow-up protocols in relatives, and the authors propose measures to accelerate its implementation in clinical care.

Natural history of hypertrophic cardiomyopathy in cats from rehoming centers: The CatScan II study

BACKGROUND

The natural history of hypertrophic cardiomyopathy (HCM) in cats has been mainly studied in cats referred for suspected heart disease, which can skew the results towards cats with clinical signs. Few data are available on factors associated with development of HCM in cats.

HYPOTHESES

(1) Clinical variables can predict which cats will develop HCM; (2) HCM in cats not referred for suspected heart disease is associated with a low rate of cardiovascular events.

ANIMALS

One hundred seven cats from rehoming centers without a history of clinical signs of cardiac or systemic disease at the time of adoption.

METHODS

Prospective longitudinal study. After rehoming, shelter cats were reexamined for serial echocardiograms. Cox regression analysis was used to identify predictors of development of HCM in cats that were normal at baseline. Adverse cardiovascular events including heart failure, thromboembolism, or sudden death were recorded.

RESULTS

Cats were monitored for a median of 5.6 [1.2-9.2] years. At baseline, 68/107 cats were normal, 18/107 were equivocal and 21/107 had HCM. Nineteen cats developed HCM during the study period. The factors at baseline associated with increased hazard of developing HCM were lower left atrial fractional shortening, higher left ventricular fractional shortening, and higher body weight. Cardiovascular events were observed in 21% of cats with HCM.

CONCLUSIONS AND CLINICAL IMPORTANCE

Cardiovascular events were common in cats with HCM from a rehoming center study sample. Lower left atrial systolic function appears to precede overt HCM.

Myocardial early systolic lengthening predicts mid-term outcomes in patients with hypertrophic cardiomyopathy

In this study, we investigated whether early systolic lengthening (ESL) which reflects subclinical ischemia and other echocardiographic and clinic parameters predict primary outcome [appropriate ICD shock, cardiovascular mortality and ventricular tachycardia (VT) or fibrillation] in patients with hypertrophic cardiomyopathy (HCM). 202 Patients with HCM (68% male, mean age 48 ± 13.9 years) were included in the study. Patients' clinical, electrocardiographic, 2D classic and speckle tracking echocardiography (STE) data were collected. ESL was defined as time from onset of the Q wave on ECG (onset of the R wave if the Q wave was absent) to maximum myocardial systolic lengthening. Patients were divided into two groups as occurrence or absence of primary outcome during 5 years follow up. During the follow-up period of 5 years (mean follow-up duration, 45.9 ± 10.8 months), 31 patients (15%) developed primary outcome [appropriate ICD shock 22 (11%), cardiovascular death 6 (3%), VT/VF 3(1.5%)]. Higher HCM Risk SCD score, longer ESL, and decreased global longitudinal peak strain (GLPS) were observed in patients with primary outcome. A Cox regression analysis, ESL, GLPS and HCM Risk SCD score were found to be independent predictors of occurrence of primary outcome. In ROC curve analysis, ESL > 53.5 msn could discriminate between groups with and without a primary outcome (AUC 0.768, 80% sensitivity and 60% specificity, CI 95% 0.666-0.871). ESL were found to be predictive for primary outcome in patients with HCM. Readily measurable ESL could be helpful to distinguish patients at high risk who could optimally benefit from ICD therapy.

Global and regional echocardiographic strain to assess the early phase of hypertrophic cardiomyopathy due to sarcomeric mutations

AIMS

Hypertrophic cardiomyopathy (HCM) is a genetic disease with delayed cardiac expression. Our objective was to characterize left ventricular (LV) myocardial strain by two-dimensional echocardiography in sarcomeric mutation carriers before the hypertrophic stage.

METHODS AND RESULTS

We studied 140 adults [derivation cohort (n = 79), validation cohort (n = 61)]. The derivation cohort comprised 38 confirmed HCM patients with hypertrophy (LVH+/Gen+), 20 mutation carriers without LV hypertrophy (LVH-/Gen+), and 21 healthy controls. LV global longitudinal strain was not different in LVH-/Gen+ compared with controls [20.6%, interquartile (IQ): 18.3/24.2 vs. 22.9%, IQ: 20.9/26.8] but was reduced in LVH+/Gen+ patients (14.1%, IQ: 11.8/18.5, P < 0.001). Regional peak longitudinal strain was significantly decreased in LVH-/Gen+ when compared with controls in four segments: basal anteroseptal (BAS) wall (P = 0.018), basal inferoseptal wall (P = 0.047), basal inferior wall (P = 0.006), and mid anteroseptal wall (P = 0.022). Receiver operating characteristic analysis identified that BAS strain <16.5% had a sensitivity (Se), specificity (Sp), positive and negative predictive values (PPV, NPV) of 57%, 90%, 82%, and 67%, respectively, to differentiate LVH-/G+ patients from controls. Similarly, the accuracy of a ratio between basal inferoseptal/basal anterolateral (BIS/BAL) strain <0.76 was 73%, 92%, 82%, and 64%, respectively (Se/Sp/PPV/NPV). In the validation cohort, the accuracy of BAS and BIS/BAL was 39%/93%/87%/57% and 55%/96%/95%/64% (Se/Sp/PPV/NPV), respectively, to differentiate the LVH-/Gen+ group from controls.

CONCLUSION

Regional longitudinal strain, but not global strain, was significantly reduced at the early stage of HCM before LV hypertrophy. This suggests that the inclusion of strain (BAS < 16.5%; BIS/BAL < 0.76) in the evaluation of HCM relatives would help identify mutation carriers and early LV abnormalities.

Non-invasive prediction of genotype positive-phenotype negative in hypertrophic cardiomyopathy by 3D modern shape analysis

NEW FINDINGS

What is the central question of this study? Can impaired deformational indicators for genotype positive for hypertrophic cardiomyopathy in subjects that do not exhibit a left-ventricular wall hypertrophy condition (G+LVH-) be determined using non-invasive 3D echocardiography? What is the main finding and its importance? Using 3D-STE and modern shape analysis, peculiar deformational impairments can be detected in G+LVH- subjects that can be classified with good accuracy. Moreover, the patterns of impairment are located mainly on the apical region in agreement with other evidence coming from previous biomechanical investigations.

ABSTRACT

We propose a non-invasive procedure for predicting genotype positive for hypertrophic cardiomyopathy (HCM) in subjects that do not exhibit a left-ventricular wall hypertrophy condition (G+LVH-); the procedure is based on the enhanced analysis of medical imaging from 3D speckle tracking echocardiography (3D-STE). 3D-STE, due to its low quality images, has not been used so far to detect effectively the G+LVH- condition. Here, we post-processed echocardiographic images exploiting the tools of modern shape analysis, and we studied the motion of the left ventricle (LV) during an entire cycle. We enrolled 82 controls, 21 HCM patients and 11 G+LVH- subjects. We followed two steps: (i) we selected the most impaired regions of the LV by analysing its strains; and (ii) we used shape analysis on these regions to classify the subjects. The G+LVH- subjects showed different trajectories and deformational attributes. We found high classification performance in terms of area under the receiver operating characteristic curve (∼90), sensitivity (∼78) and specificity (∼79). Our results showed that (i) G+LVH- subjects present important deformational impairments relative to healthy controls and (ii) modern shape analysis can efficiently predict genotype by means of a non-invasive and inexpensive technique such as 3D-STE.

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.

Assessment of myocardial oxygenation, strain, and diastology in MYBPC3-related hypertrophic cardiomyopathy: a cardiovascular magnetic resonance and echocardiography study

Aims

Myocardial oxygenation is impaired in hypertrophic cardiomyopathy (HCM) patients with left ventricular hypertrophy (LVH), and possibly also in HCM gene carriers without LVH. Whether these oxygenation changes are also associated with abnormalities in diastolic function or left ventricular (LV) strain are unknown.

Methods and results

We evaluated 60 subjects: 20 MYBPC3 gene positive patients with LVH (G+LVH+), 18 MYBPC3 gene positive without LVH (G+LVH−), 11 gene negative siblings (G−), and 11 normal controls (NC). All subjects underwent 2D transthoracic echocardiography and cardiovascular magnetic resonance imaging for assessment of ventricular volumes, mass, and myocardial oxygenation at rest and adenosine stress using the blood oxygen level dependent (BOLD) technique. Maximal septal thickness was 20 mm in the G+LVH+ group, vs. 9 mm for the G+LVH− group. As expected, the G+LVH+ group had a more blunted myocardial oxygenation response to stress when compared with the G+LVH− group (−5% ± 3% vs. 2% ± 4%, P < 0.05), G− siblings (−5% ± 3% vs. 11% ± 4%, P < 0.0001) and NC (−5% ± 3% vs. 15% ± 4%, P < 0.0001). A blunted BOLD response to stress was also seen in G+LVH− subjects when compared with gene negative siblings (2% ± 4% vs. 11% ± 4%, P < 0.05) and NC (15% ± 4%, P < 0.050). G+LVH+ patients exhibited abnormal diastolic function including lower Eʹ, higher E to Eʹ ratio and greater left atrial area compared with the G+LVH− subjects who all had normal values for these indices.

Conclusion

Myocardial deoxygenation during stress is observed in MYBPC3 HCM patients, even in the presence of normal LV diastolic function, LV global longitudinal strain, and LV wall thickness.

Multilayer Myocardial Mechanics in Genotype-Positive Left Ventricular Hypertrophy-Negative Patients With Hypertrophic Cardiomyopathy

It is unknown whether the presence of a sarcomeric mutation alone is sufficient to result in abnormal myocardial force generation, or whether additional changes in myocardial architecture (hypertrophy, disarray, and fibrosis) are required to impair systolic function. Speckle tracking echocardiography allows quantification of global strain/strain rates, twist, and dyssynchrony. In the present study we sought to further elucidate early abnormalities of myocardial mechanics in sarcomeric mutation carriers without evidence of clinical disease. Sixty genotype-positive left ventricular hypertrophy-negative (G+left ventricular hypertrophy [LVH]-) patients and 60 normal controls were studied. Velocity vector imaging was applied retrospectively to echocardiographic images to quantify global longitudinal and circumferential strain/strain rate, and rotation parameters. The G+LVH- group demonstrated both smaller left ventricular diastolic cavity dimensions (4.5 ± 0.6 cm vs 4.8 ± 0.4 cm) and a higher LVEF (66 ± 6% vs 60 ± 5%) compared with controls. An increase in circumferential subendocardial systolic strain (-30 ± 5 vs -27 ± 3%) and both systolic and diastolic subendocardial strain rate was seen in the G+LVH- group. Peak rotation angles were higher at the base and apex, with an increase in total twist (9.0 ± 3.8 vs 6.9 ± 2.9). In the control group, global and average segmental strain were similar, suggesting no/minimal dyssynchrony (global mechanical synchrony index [GMSi] 0.97-0.98). In the G+LVH- group GMSi was significantly lower (subendocardial GMSi 0.95; subepicardial GMSi 0.60), suggesting increasing subendocardial to subepicardial dyssynchrony. In conclusion, utilizing multilayer strain analysis, we demonstrate that G+LVH- subjects have enhanced subendocardial systolic strain rate and twist, as well as mechanical dyssynchrony within the left ventricular myocardium. These results demonstrate that abnormalities in myocardial mechanics precede the development of clinical hypertrophy.

Left ventricular twist in hypertrophic cardiomyopathy : Predictor of nonsustained ventricular tachycardia

BACKGROUND

We investigated the efficacy of clinical and classic echocardiographic parameters in predicting the occurrence of nonsustained ventricular tachycardia (NsVT) in patients with hypertrophic cardiomyopathy (HCM).

METHODS

The study comprised 59 patients with HCM (47 male, [80%]; mean age, 48.48 ± 14.16 years). Clinical, electrocardiographic, as well as classic two-dimensional and speckle-tracking echocardiography (STE) data were collected. All patients had Holter monitoring within 24-72 h of the echocardiographic examination. NsVT was defined as three or more consecutive premature wide QRS complexes with a heart rate of > 100 bpm. The patient population was categorized into groups based on the occurrence or absence of NsVT on the 24-h Holter recordings.

RESULTS

NsVT was observed in 17 patients (29%). In these patients, higher twist (14.4 ± 3.8 vs.18 ± 7.9; p = 0.02), higher apical rotation (8.7 ± 4.2 vs. 12.2 ± 7; p = 0.02), higher sudden cardiac death risk score (4.4 ± 2.2 vs. 7 ± 3.3; p = 0.007), and decreased global longitudinal peak strain (GLPS; -12.8 ± 3.1 vs. -10.6 ± 2.8; p = 0.014) were observed. In the multivariate logistic regression analysis, including GLPS and twist, GLPS (Odds Ratio [OR]: 1.406; 95% CI: 1.087-1.818; p = 0.009) and twist (OR: 1.236; 95% CI: 1.056-1.446; p = 0.008) were found to be independent predictors of NsVT. In the receiver operating characteristic curve analysis, GLPS < -11.9% predicted NsVT with 82% sensitivity and 60% specificity (area under the curve [AUC]: 0.70; p = 0.014) and twist > 15.2° predicted NsVT with 70% sensitivity and 58% specificity (AUC: 0.69; p = 0.027).

CONCLUSION

Decreased GLPS and increased twist were predictive of NsVT in HCM patients. Parameters that can easily be measured with STE can help detect patients who may develop arrhythmia.

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.

The systolic paradox in hypertrophic cardiomyopathy

Objective

We explored cardiac volumes and the effects on systolic function in hypertrophic cardiomyopathy (HCM) patients with left ventricular hypertrophy (HCM LVH+) and genotype-positive patients without left ventricular hypertrophy (HCM LVH−).

Methods

We included 180 HCM LVH+, 100 HCM LVH− patients and 80 healthy individuals. End-Diastolic Volume Index (EDVI), End-Systolic Volume Index (ESVI) and ejection fraction (EF) were assessed by echocardiography. Left ventricular (LV) global longitudinal strain (GLS) was measured by speckle tracking echocardiography.

Results

EDVI and ESVI were significantly smaller in HCM LVH+ compared with HCM LVH− patients (41±14 mL/m² vs 49±13 mL/m² and 16±7 mL/m² vs 19±6 mL/m², respectively, both p<0.001) and in healthy individuals (41±14 mL/m² vs 57±14 mL/m² and 16±7 mL/m² vs 23±9 mL/m², respectively, both p<0.001). HCM LVH− patients had significantly lower EDVI and ESVI compared with healthy individuals (49±13 mL/m² vs 57±14 mL/m² and 19±6 mL/m² vs 23±9 mL/m², both p<0.001). EF was similar (61%±7% vs 60%±8% vs 61%±6%, p=0.43) in the HCM LVH+, HCM LVH– and healthy individuals, despite significantly worse GLS in the HCM LVH+ (−16.4%±3.7% vs −21.3%±2.4% vs −22.3%±3.7%, p<0.001). GLS was worse in the HCM LVH− compared with healthy individuals in pairwise comparison (p=0.001). Decrease in ESVI was closely related to EF in HCM LVH+ and HCM LVH− (R=0.45, p<0.001 and R=0.43, p<0.001) as expected, but there was no relationship with GLS (R=0.02, p=0.77 and R=0.11, p=0.31). Increased maximal wall thickness (MWT) correlated significantly with worse GLS (R=0.58, p<0.001), but not with EF (R=0.018, p=0.30) in the HCM LVH+ patients.

Conclusion

HCM LVH+ had smaller cardiac volumes that could explain the preserved EF, despite worse GLS that was closely related to MWT. HCM LVH− had reduced cardiac volumes and subtle changes in GLS compared with healthy individuals, indicating a continuum of both volumetric and systolic changes present before increased MWT.

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.

Current perspectives in hypertrophic cardiomyopathy with the focus on patients in the Finnish population: a review

Hypertrophic cardiomyopathy (HCM) is the most common inherited heart disease, with the prevalence of about 1/500. During the last two decades, the knowledge of the etiology, pathogenesis, risk stratification and prevention of sudden death in HCM has substantially advanced. Most often, HCM is familial and caused by mutations in sarcomere genes, inherited in an autosomal dominant manner. In Finland, genetic background of HCM is unique, with a few founder mutations in cardiac sarcomere genes accounting for a considerable proportion of the disease. Pathogenic mechanisms induced by disease-causing mutations are still poorly understood, although alterations in intracellular calcium handling and inefficient generation of contractile force in myocytes are considered key features in triggering the hypertrophic response. Clinical features of the disease are highly variable from no symptoms to the spectrum of exertional dyspnea, angina, palpitations, syncope and sudden death. In the current patient care, implantable cardioverter defibrillators (ICDs) are successfully used to prevent sudden cardiac death in high risk subjects. Targeted genetic testing is recommended to confirm the diagnosis in patients with HCM and to identify family members with the disease. Future research is needed to elucidate key cellular mechanisms leading to HCM, which may allow specific prevention and treatment of the disease. Key messages Hypertrophic cardiomyopathy, most often caused by defects in sarcomere genes, is the most common inherited heart disease, and a common cause of sudden cardiac death (SCD) in athletes and young subjects. Cardiac imaging, ECG and genetic testing are pivotal in the diagnosis of the disease in patients and first-degree relatives. Implantable cardioverter defibrillators in patients with high risk for SCD and tailored pharmacotherapy are efficient tools in patient care, but so far, exact mechanisms leading to cardiac hypertrophy in HCM are only partially understood, and there is no curative treatment for the disease.

Morphological and functional abnormalities pattern in hypertrophy-free HCM mutation carriers detected with echocardiography

To evaluate if morphological or functional abnormalities could be detected with echocardiography in hypertrophic myocardiopathy (HCM) mutation carriers without left ventricle (LV) hypertrophy has developed. HCM is caused by extensive genes mutations found in two-third of patients. Because screening for carriership of a large population is unreasonable, identification of asymptomatic subjects is confined to the use of imaging such as echocardiography, by which subtle abnormalities can be detected. Comprehensive echocardiographic studies including morphological and functional assessment were performed. Asymptomatic HCM mutation carriers without hypertrophy (Phe-/Gen+, n = 14), and HCM patients (Phe+/Gen+, n = 17) were compared with healthy control subjects (n = 32) in a prospective design. Compared to controls, septum thickness was significantly higher with an elongated mitral valve in both groups. Thickened LV muscular band (LVMB) are more likely found in Phe-/Gen+ and Phe+/Gen+. The thickness of LVMB was higher in the Phe-/Gen+ versus controls. A LVMB thickness ≥3.6 mm was associated with HCM mutation carriership (sensitivity: 76.9 %, specificity: 94.1 %). The regional strain was significantly impaired in the basal segments of the septum in the Phe-/Gen+. The GLS was significantly impaired in the Phe+/Gen+ (-16.4 % ± 2.9 vs. -21.4 % ± 2.3 in control subjects, p = 0.01). Mitral A wave velocity, septal E/e', averaged E/e' were increased in both groups. E/A ratio was significantly lower in Phe+/Gen+. Morphological and functional abnormalities in hypertrophy-free HCM mutation carriers could be detected with echocardiography. Anomalous thickened LVMB could be representing a morphological marker for the HCM disease without overt hypertrophy has developed or in patients with an ambiguous diagnosis.

A Long Term Follow-up Study of Carriers of Hypertrophic Cardiomyopathy Mutations

BACKGROUND

Adults who test positive for a mutation associated with the development of hypertrophic cardiomyopathy (HCM) but who have not manifested left ventricular hypertrophy (LVH) at the time of that diagnosis are now commonly identified in the era of genetic testing. There are little published data, however, on the long-term outlook for these phenotypically normal gene carriers.

METHODS

Fifteen genotype positive/LVH negative patients with HCM were identified, seven of which were children when first diagnosed as gene carriers. Fourteen were followed up with clinical examinations, electrocardiography and echocardiography to determine if their clinical status had changed over time. Measurements included electrocardiographic changes, changes in wall thickness, diastolic function and global longitudinal stain.

RESULTS

Ten participants were followed up for a total of 18 years, two for a total of 17 years, one for 11 years and one for 8 years. In addition, magnetic resonance imaging (MRI) studies were performed on 11 participants. Eleven participants carried a mutation for the MYBPC3 gene and three carried a mutation for the MYH7 gene. One patient, an adult at the time of initial investigation, developed phenotypic features of HCM on echocardiography and MRI, one an increase in wall thickness diagnostic for HCM only on MRI and another to be borderline for HCM on MRI.

CONCLUSION

Hypertrophic cardiomyopathy can develop in adult life in carriers who may be negative for LVH at the time of gene diagnosis and warrants periodic supervision of carriers throughout their lives.

Abnormal Mitral Valve Dimensions in Pediatric Patients with Hypertrophic Cardiomyopathy

The hearts of patients with hypertrophic cardiomyopathy (HCM) show structural abnormalities other than isolated wall thickening. Recently, adult HCM patients have been found to have longer mitral valve leaflets than control subjects. The aim of the current study was to assess whether children and adolescents with HCM have similar measureable differences in mitral valve leaflet dimensions when compared to a healthy control group. Clinical and echocardiographic data from 46 children with myocardial hypertrophy and a phenotype and/or genotype consistent with sarcomeric HCM were reviewed. Cardiac magnetic resonance imaging studies were evaluated. The anterior and posterior mitral valve leaflet lengths and myocardial structure were compared to 20 healthy controls. The anterior mitral valve was longer in the HCM group than in the control group (28.4 ± 4.9 vs. 25.2 ± 3.6 mm in control patients, p = 0.013) as was the posterior mitral valve leaflet (16.3 ± 3.0 vs. 13.1 ± 2.3 mm for controls <0.0001). There was no correlation between the resting left ventricular outflow tract gradient and anterior mitral valve leaflet length, nor was the anterior mitral valve leaflet longer in those with systolic anterior motion of the mitral valve compared to those without (28.9 ± 6.1 vs. 28.1 ± 4.5 mm, p = 0.61). Children and adolescents with HCM have abnormally long mitral valve leaflets when compared with healthy control subjects. These abnormalities do not appear to result in, or be due to, obstruction to left ventricular outflow. The mechanism of this mitral valve elongation is not clear but appears to be independent of hemodynamic disturbances.

FHL2 expression and variants in hypertrophic cardiomyopathy

Based on evidence that FHL2 (four and a half LIM domains protein 2) negatively regulates cardiac hypertrophy we tested whether FHL2 altered expression or variants could be associated with hypertrophic cardiomyopathy (HCM). HCM is a myocardial disease characterized by left ventricular hypertrophy, diastolic dysfunction and increased interstitial fibrosis and is mainly caused by mutations in genes coding for sarcomeric proteins. FHL2 mRNA level, FHL2 protein level and I-band-binding density were lower in HCM patients than control individuals. Screening of 121 HCM patients without mutations in established disease genes identified 2 novel (T171M, V187L) and 4 known (R177Q, N226N, D268D, P273P) FHL2 variants in unrelated HCM families. We assessed the structural and functional consequences of the nonsynonymous substitutions after adeno-associated viral-mediated gene transfer in cardiac myocytes and in 3D-engineered heart tissue (EHT). Overexpression of FHL2 wild type or nonsynonymous substitutions in cardiac myocytes markedly down-regulated α-skeletal actin and partially blunted hypertrophy induced by phenylephrine or endothelin-1. After gene transfer in EHTs, force and velocity of both contraction and relaxation were higher with T171M and V187L FHL2 variants than wild type under basal conditions. Finally, chronic phenylephrine stimulation depressed EHT function in all groups, but to a lower extent in T171M-transduced EHTs. These data suggest that (1) FHL2 is down-regulated in HCM, (2) both FHL2 wild type and variants partially protected phenylephrine- or endothelin-1-induced hypertrophy in cardiac myocytes, and (3) FHL2 T171M and V187L nonsynonymous variants induced altered EHT contractility. These findings provide evidence that the 2 novel FHL2 variants could increase cardiac function in HCM.

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.

Significance of left ventricular apical-basal muscle bundle identified by cardiovascular magnetic resonance imaging in patients with hypertrophic cardiomyopathy

AIMS

Cardiovascular magnetic resonance (CMR) has improved diagnostic and management strategies in hypertrophic cardiomyopathy (HCM) by expanding our appreciation for the diverse phenotypic expression. We sought to characterize the prevalence and clinical significance of a recently identified accessory left ventricular (LV) muscle bundle extending from the apex to the basal septum or anterior wall (i.e. apical-basal).

METHODS AND RESULTS

CMR was performed in 230 genotyped HCM patients (48 ± 15 years, 69% male), 30 genotype-positive/phenotype-negative (G+/P-) family members (32 ± 15 years, 30% male), and 126 controls. Left ventricular apical-basal muscle bundle was identified in 145 of 230 (63%) HCM patients, 18 of 30 (60%) G+/P- family members, and 12 of 126 (10%) controls (G+/P- vs. controls; P < 0.01). In HCM patients, the prevalence of an apical-basal muscle bundle was similar among those with disease-causing sarcomere mutations compared with patients without mutation (64 vs. 62%; P = 0.88). The presence of an LV apical-basal muscle bundle was not associated with LV outflow tract obstruction (P = 0.61). In follow-up, 33 patients underwent surgical myectomy of whom 22 (67%) were identified to have an accessory LV apical-basal muscle bundle, which was resected in all patients.

CONCLUSION

Apical-basal muscle bundles are a unique myocardial structure commonly present in HCM patients as well as in G+/P- family members and may represent an additional morphologic marker for HCM diagnosis in genotype-positive status.

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.

Tissue Doppler imaging and plasma N-terminal probrain natriuretic peptide for the identification of hypertrophic cardiomyopathy mutation carriers

Previous studies have shown that tissue Doppler imaging (TDI) is able to identify mutation carriers of hypertrophic cardiomyopathy (HC) before the development of the clinical phenotype. However, data are scarce and have sometimes been controversial. We performed a systematic study that included conventional echocardiography, TDI, and plasma NT-probrain natriuretic peptide (NT-proBNP) measurement to evaluate the parameters that could identify HC mutation carriers. A total of 138 genotyped subjects were included and divided into 3 groups: group 1, those with HC (n = 62); group 2, mutation carriers (first-degree relatives with a positive genotype but negative phenotype; n = 34); and group 3, controls (first-degree relatives with a negative genotype and phenotype; n = 42). An echocardiographic study, including TDI, was performed on all subjects, and a TDI-derived index (global function index) was also determined. The age-adjusted mean differences in the echocardiographic and TDI parameters and NT-proBNP levels were compared among the 3 groups. Compared with the HC group, the carriers had significantly higher mean E' velocities, lower mean E/E' ratio, higher mean S' velocities, and lower mean global function index and NT-proBNP values. The carriers and controls did not differ significantly either in the echocardiographic parameters studied or in the NT-proBNP levels. In conclusion, the echocardiographic and TDI parameters and NT-proBNP levels cannot be used to identify the HC mutation carrier state and therefore do not appear to be reliable for the purpose of making a preclinical diagnosis of the disease.

Two-dimensional speckle tracking echocardiography for early detection of myocardial damage in young patients with Fabry disease

Fabry disease (FD) is characterized by left ventricular hypertrophy (LVH). Conventional echocardiography is not sensitive enough to perform the preclinical diagnosis To assess whether longitudinal myocardial strain of the left ventricle (LV), using speckle tracking, is useful to detect early myocardial involvement in FD. Forty-four patients with FD who were diagnosed with genetic testing were prospectively included and were compared to a sex-matched control group. They were divided into three groups: 22 with LVH (Group I), 22 without LVH (Group II), and 22 healthy volunteers (Group III). LV longitudinal strain was measured from the apical views. An ANOVA test was used for multiple comparisons for variables with a normal distribution, and a Kruskal-Wallis test was used for variables with non-Gaussian distribution. Longitudinal LV strain was different in the three groups: it was ≥-15% in at least one segment in all Group I patients, in 50% of patients of Group II and in no patient of Group III. Seventy percent of the segments with abnormal strain in Group II were located in the basal regions (32/46). These findings show that the presence of at least one strain value ≥-15% demonstrates subclinical myocardial dysfunction in patients with preclinical FD. Longitudinal myocardial LV strain measured with speckle tracking is a useful tool to detect early myocardial involvement in young patients with FD. This information allows the detection and treatment of myocardial dysfunction at an early stage, which is of high clinical importance.

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

BACKGROUND

Tissue Doppler imaging (TDI) of the mitral annulus has been proposed as an alternative for the identification of hypertrophic cardiomyopathy (HCM) genetically affected subjects without left ventricular hypertrophy (G+/LVH-). Unfortunately, conflicting results have been described in the literature, potentially caused by the angle-dependency of TDI. This study sought to assess abnormalities in mitral annular velocities in G+/LVH- subjects as detected by speckle tracking echocardiography (STE).

METHODS

The study population consisted of 23 consecutive genotyped family members without major or minor criteria for the diagnosis of HCM (mean age 37 ± 13 years, 9 men) and 23 healthy volunteers (age 38 ± 12 years, 12 men) who prospectively underwent STE.

RESULTS

There were no significant differences in global peak systolic annular velocity (7.4 ± 1.2 vs. 7.1 ± 1.0 cm/sec) and early diastolic annular velocity (10.2 ± 2.5 vs. 11.3 ± 2.2 cm/sec) between G+/LVH- and control subjects. Global peak late diastolic annular velocity was higher in G+/LVH- subjects (8.1 ± 1.7 vs. 5.7 ± 1.1 cm/sec, P < 0.001). Regionally, this difference was seen in all 6 studied LV walls.

CONCLUSIONS

This STE study confirms our previous TDI observations on increased peak late diastolic annular velocities in G+/LVH- subjects. Because of the complete overlap in early diastolic annular velocities this parameter cannot be used in the genotypes we studied to differentiate genotype (+) from genotype (-) individuals.