Differences in the diagnostic value of various criteria of negative T waves for hypertrophic cardiomyopathy based on a molecular genetic diagnosis

Deciphering hypertrophic cardiomyopathy with electrocardiography

The comprehensive assessment of patients with hypertrophic cardiomyopathy is a complex process, with each step concurrently focusing on confirmation of the diagnosis, differentiation between sarcomeric and non-sarcomeric disease (phenocopy), and prognostication. Novel modalities such as genetic testing and advanced imaging have allowed for substantial advancements in the understanding of this condition and facilitate patient management. However, their availability is at present not universal, and interpretation requires a high level of expertise. In this setting, electrocardiography, a fast and widely available method, still retains a significant role in everyday clinical assessment of this population. In our review, we follow a stepwise approach for the interpretation of each electrocardiographic segment, discussing clinical implications of electrocardiographic patterns in sarcomeric disease, their value in the differential diagnosis from phenocopies, and impact on patient management. Outlining the substantial amount of information to be obtained from a simple tracing, we exhibit how electrocardiography is likely to remain an integral diagnostic tool in the future as well.

Apical hypertrophic cardiomyopathy with preexcitation presenting as a myocardial infarction and ischemic stroke with a history of recurrent syncope: A case report

Contrast-enhanced echocardiography or cardiac magnetic resonance imaging is of value in the diagnosis of apical hypertrophic cardiomyopathy. Apical hypertrophic cardiomyopathy is rare in Caucasians, and gene negativity does not rule out the diagnosis. Risk stratification for sudden cardiac death and decisions about anticoagulation in cases with atrial fibrillation should be based on guidelines.

Impact of T wave amplitude in lead aVR on predicting cardiac events in ischemic and nonischemic cardiomyopathy patients with an implantable cardioverter defibrillator

BACKGROUND

T wave amplitudes during ventricular repolarization in the lead aVR (TAaVR) are shown to be associated with adverse cardiac events in patients with several cardiovascular diseases, such as postmyocardial infarction. However, the utility of TAaVR has not been previously evaluated in patients with cardiomyopathy who have received implantable cardioverter defibrillators (ICD). Patients with ischemic or nonischemic cardiomyopathy (ICM or NICM, respectively) and who received an ICD may experience worsening of their condition due to the introduction of electric shock during treatment. This study aimed to investigate the utility of TAaVR in the prediction of cardiac events in ICM or NICM patients with ICD.

METHODS

Ninety-three consecutive ICM or NICM patients with ICD were retrospectively analyzed (median age: 64 years; male: 77.4%; ICD for secondary prevention: 76.3%; NICM: 64.5%). The median follow-up period was 31 months. The primary endpoint was defined as composite cardiac events, including cardiac death, major ventricular arrhythmic events (MVAE), or hospitalization due to heart failure (HHF).

RESULTS

Multivariate Cox regression analysis demonstrated that less negative TAaVR (-0.1 mV ≤ TAaVR <0 mV and 0 mV ≤ TAaVR) was independently associated with the primary endpoint (HR: 3.75; 95% confidence interval [CI]: 1.09-23.7; p = .04). Kaplan-Meier curve also revealed that the event free survival rate in the less negative TAaVR group was significantly lower than that in the normal TAaVR group (<-0.1 mV) (p < .01).

CONCLUSIONS

TAaVR is useful in risk stratification for cardiac events in ICM or NICM patients with ICD.

Clinical disease presentation and ECG characteristics of LMNA mutation carriers

Objective

Mutations in the LMNA gene encoding lamins A and C of the nuclear lamina are a frequent cause of cardiomyopathy accounting for 5–8% of familial dilated cardiomyopathy (DCM). Our aim was to study disease onset, presentation and progression among LMNA mutation carriers.

Methods

Clinical follow-up data from 27 LMNA mutation carriers and 78 patients with idiopathic DCM without an LMNA mutation were collected. In addition, ECG data were collected and analysed systematically from 20 healthy controls.

Results

Kaplan-Meier analysis revealed no difference in event-free survival (death, heart transplant, resuscitation and appropriate implantable cardioverter-defibrillator therapy included as events) between LMNA mutation carriers and DCM controls (p=0.5). LMNA mutation carriers presented with atrial fibrillation at a younger age than the DCM controls (47 vs 57 years, p=0.003). Male LMNA mutation carriers presented with clinical manifestations roughly a decade earlier than females. In close follow-up non-sustained ventricular tachycardia was detected in 78% of LMNA mutation carriers. ECG signs of septal remodelling were present in 81% of the LMNA mutation carriers, 21% of the DCM controls and none of the healthy controls giving a high sensitivity and specificity for the standard ECG in distinguishing LMNA mutation carriers from patients with DCM and healthy controls.

Conclusions

Male LMNA mutation carriers present clinical manifestations at a younger age than females. ECG septal remodelling appears to distinguish LMNA mutation carriers from healthy controls and patients with DCM without LMNA mutations.

Whole exome sequencing combined with integrated variant annotation prediction identifies a causative myosin essential light chain variant in hypertrophic cardiomyopathy

BACKGROUND

The development of candidate gene approaches to enable molecular diagnosis of hypertrophic cardiomyopathy (HCM) has required extensive and prolonged efforts. Whole exome sequencing (WES) technologies have already accelerated genetic studies of Mendelian disorders, yielding approximately 30% diagnostic success. As a result, there is great interest in extending the use of WES to any of Mendelian diseases. This study investigated the potential of WES for molecular diagnosis of HCM.

METHODS

WES was performed on seven relatives from a large HCM family with a clear HCM phenotype (five clinically affected and two unaffected) in the Kanazawa University Hypertrophic Cardiomyopathy Registry. Serial bioinformatics filtering methods as well as using combined annotation dependent depletion (CADD) score and high heart expression (HHE) gene data were applied to detect the causative variant. Moreover, additional carriers of the variant were investigated in the HCM registry, and clinical characteristics harboring the variant were collected and evaluated.

RESULTS

WES detected 60020 rare variants in the large HCM family. Of those, 3439 were missense, nonsense, splice-site, or frameshift variants. After genotype-phenotype matching, 13 putative variants remained. Using CADD score and HHE gene data, the number of candidates was reduced to one, a variant in the myosin essential light chain (MYL3, NM_000258.2:c.281G>A, p.Arg94His) that was shared by the five affected subjects. Additional screening of the HCM registry (n=600) identified two more subjects with this variant. Serial assessments of the variant carriers revealed the following phenotypic characteristics: (1) disease-penetrance of 88%; (2) all clinically affected carriers exhibited asymmetric septal hypertrophy with a substantial maximum left ventricular wall thickness of 18±3mm without any obstruction.

CONCLUSIONS

WES combined with CADD score and HHE gene data may be useful even in HCM. Furthermore, the MYL3 Arg94His variant was associated with high disease penetrance and substantial interventricular septal hypertrophy.

Fragmented QRS predicts heart failure progression in patients with hypertrophic cardiomyopathy

BACKGROUND

Although fragmented QRS complex (frag-QRS) reflecting intra-ventricular conduction delay has been shown to be a prognostic marker for cardiac events, few data exist regarding the impact of frag-QRS on cardiac events in hypertrophic cardiomyopathy (HCM).

METHODS AND RESULTS

Ninety-four HCM patients (56 male; mean age, 58 ± 17 years) were retrospectively investigated. Frag-QRS was defined as the presence of various RsR' patterns in at least 2 contiguous ECG leads. Major arrhythmic events (MAE) were defined as sudden cardiac death, and combined sustained ventricular tachycardia/ventricular fibrillation. New-onset atrial fibrillation (AF) was diagnosed based on ECG during provisional or routine medical examination. Heart failure (HF) with hospitalization was defined as hospital admission due to subjective or objective symptoms. Frag-QRS was detected in 31 patients (33%).TNNI3 was the most frequent disease-causing gene. Median follow-up was 4.6 years. The 4-year cumulative survival rates of cardiac death, MAE, new-onset AF and HF with hospitalization were 97.6%, 94.6%, 87.5% and 89.3%, respectively. On multivariate analysis, frag-QRS was significantly associated with HF with hospitalization (adjusted hazard ratios [95% confidence intervals]: 5.4 [1.2-36], P=0.03). Moreover, HF-free survival was significantly lower in the frag-QRS (+) group compared to the frag-QRS (-) group (79.0% vs. 95.1%, P=0.03).

CONCLUSIONS

Frag-QRS is associated with HF with hospitalization in HCM patients who had a unique distribution of gene mutations.

Compound heterozygosity deteriorates phenotypes of hypertrophic cardiomyopathy with founder MYBPC3 mutation: evidence from patients and zebrafish models

Although most founder mutation carriers of hypertrophic cardiomyopathy (HCM), such as the cardiac myosin-binding protein C gene (MYBPC3), arose from a common ancestor exhibit favorable clinical phenotypes, there still remain small fractions of these carriers associated with increased cardiovascular events. However, few data exist regarding the defining factors that modify phenotypes of these patients, particularly in terms of multiple gene mutations. Therefore, we assessed genotype-phenotype correlations and investigated factors that contribute to phenotypic diversities of mutation carriers from 488 unrelated HCM probands. A prevalent founder mutation (Val762Asp) in MYBPC3 was identified in 33 subjects from 19 families. Among them, 28 carriers harbored an isolated Val762Asp mutation and exhibited a late onset of overt HCM compared with other MYBPC3 mutation carriers (62.8 ± 3.0 vs 50.1 ± 2.6 yr, P < 0.05). In contrast, the remaining five carriers had additional sarcomere gene mutations (3 carriers in MYBPC3 and 2 carriers in the cardiac troponin T gene). Of these five carriers, two carriers showed early disease onset and one carrier exhibited end-stage HCM. These phenotypes were recapitulated in zebrafish models; injection of MYBPC3 Val762Asp alone did not alter ventricular size or function, but ventricular dimension was significantly increased when MYBPC3 Val762Asp mRNA was coinjected with MYBPC3 Arg820Gln mRNA. These results demonstrate that MYBPC3 Val762Asp may be associated with unfavorable HCM phenotypes in some cases when combined with another MYBPC3 mutation.

Hypertrophic cardiomyopathy: Can the noninvasive diagnostic testing identify high risk patients?

Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death (SCD) in the young, particularly among athletes. Identifying high risk individuals is very important for SCD prevention. The purpose of this review is to stress that noninvasive diagnostic testing is important for risk assessment. Extreme left ventricular hypertrophy and documented ventricular tachycardia and fibrillation increase the risk of SCD. Fragmented QRS and T wave inversion in multiple leads are more common in high risk patients. Cardiac magnetic resonance imaging provides complete visualization of the left ventricular chamber, allowing precise localization of the distribution of hypertrophy and measurement of wall thickness and cardiac mass. Moreover, with late gadolinium enhancement, patchy myocardial fibrosis within the area of hypertrophy can be detected, which is also helpful in risk stratification. Genetic testing is encouraged in all cases, especially in those with a family history of HCM and SCD.

The relationship between electrocardiographic changes and CMR features in asymptomatic or mildly symptomatic patients with hypertrophic cardiomyopathy

To investigate the relationship between electrocardiographic (ECG) abnormalities and left ventricular (LV) segmental hypertrophy and myocardial fibrosis assessed by cardiovascular magnetic resonance (CMR) in asymptomatic or mildly symptomatic patients with hypertrophic cardiomyopathy (HCM). 118 asymptomatic or mildly symptomatic patients with HCM were examined with late gadolinium enhancement (LGE) CMR, 12-lead ECG, and echocardiography. The distribution and magnitude of LV segmental hypertrophy and LGE were assessed and analyzed in relation to ECG abnormalities. Abnormal electrocardiograms were found in 113 of 118 (95%) patients. Negative T waves were associated with greater apical septal thickness (P = 0.009) and an increased ratio of LV septum to free wall thickness (P = 0.01). Giant negative T waves (GNT) were found in 19 patients (16%), and were associated with apical HCM (P < 0.001), greater apical thickness (P = 0.004), and increased ratio of LV apical to basal wall thickness (P < 0.001). However, no significant association was demonstrated between GNT and apical LGE (P = 0.71). Abnormal Q waves were associated with greater basal anteroseptal thickness (P = 0.001), maximal basal thickness (P = 0.004), and more segments with extensive LGE (>75% wall thickness involved) (P = 0.001). LV hypertrophy was related to greater LV mass (P = 0.002) and LV end diastolic volume (P = 0.002). In addition, a modest but significant correlation was observed between maximum LV wall thickness and the Romhilt-Estes score (r = 0.41, P < 0.001). GNT were associated with apical HCM and an increased ratio of LV apical to basal wall thickness. Abnormal Q waves were related to basal anteroseptal hypertrophy and segmental extensive LGE.