Diagnostic value of abnormal Q waves for identification of preclinical carriers of hypertrophic cardiomyopathy based on a molecular genetic diagnosis

Inherited Arrhythmias in the Pediatric Population: An Updated Overview

Pediatric cardiomyopathies (CMs) and electrical diseases constitute a heterogeneous spectrum of disorders distinguished by structural and electrical abnormalities in the heart muscle, attributed to a genetic variant. They rank among the main causes of morbidity and mortality in the pediatric population, with an annual incidence of 1.1-1.5 per 100,000 in children under the age of 18. The most common conditions are dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM). Despite great enthusiasm for research in this field, studies in this population are still limited, and the management and treatment often follow adult recommendations, which have significantly more data on treatment benefits. Although adult and pediatric cardiac diseases share similar morphological and clinical manifestations, their outcomes significantly differ. This review summarizes the latest evidence on genetics, clinical characteristics, management, and updated outcomes of primary pediatric CMs and electrical diseases, including DCM, HCM, arrhythmogenic right ventricular cardiomyopathy (ARVC), Brugada syndrome (BrS), catecholaminergic polymorphic ventricular tachycardia (CPVT), long QT syndrome (LQTS), and short QT syndrome (SQTS).

Patterns of Electrocardiographic Abnormalities in Children with Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM), a common cardiomyopathy in children, is an important cause of morbidity and mortality. Early recognition and appropriate management are important. An electrocardiogram (ECG) is often used as a screening tool in children to detect heart disease. The ECG patterns in children with HCM are not well described.ECGs collected from an international cohort of children, and adolescents (≤ 21 years) with HCM were reviewed. 482 ECGs met inclusion criteria. Age ranged from 1 day to 21 years, median 13 years. Of the 482 ECGs, 57 (12%) were normal. The most common abnormalities noted were left ventricular hypertrophy (LVH) in 108/482 (22%) and biventricular hypertrophy (BVH) in 116/482 (24%) Of the patients with LVH/BVH (n = 224), 135 (60%) also had a strain pattern (LVH in 83, BVH in 52). Isolated strain pattern (in the absence of criteria for hypertrophy) was seen in 43/482 (9%). Isolated pathologic Q waves were seen in 71/482 (15%). Pediatric HCM, 88% have an abnormal ECG. The most common ECG abnormalities were LVH or BVH with or without strain. Strain pattern without hypertrophy and a pathologic Q wave were present in a significant proportion (24%) of patients. Thus, a significant number of children with HCM have ECG abnormalities that are not typical for "hypertrophy". The presence of the ECG abnormalities described above in a child should prompt further examination with an echocardiogram to rule out HCM.

Derivation and Validation of a Screening Model for Hypertrophic Cardiomyopathy Based on Electrocardiogram Features

Background

Hypertrophic cardiomyopathy (HCM) is a widely distributed, but clinically heterogeneous genetic heart disease, affects approximately 20 million people worldwide. Nowadays, HCM is treatable with the advancement of medical interventions. However, due to occult clinical presentations and a lack of easy, inexpensive, and widely popularized screening approaches in the general population, 80–90% HCM patients are not clinically identifiable, which brings certain safety hazards could have been prevented. The majority HCM patients showed abnormal and diverse electrocardiogram (ECG) presentations, it is unclear which ECG parameters are the most efficient for HCM screening.

Objective

We aimed to develop a pragmatic prediction model based on the most common ECG features to screen for HCM.

Methods

Between April 1st and September 30th, 2020, 423 consecutive subjects from the International Cooperation Center for Hypertrophic Cardiomyopathy of Xijing Hospital [172 HCM patients, 251 participants without left ventricular hypertrophy (non-HCM)] were prospectively included in the training cohort. Between January 4th and February 30th, 2021, 163 participants from the same center were included in the temporal internal validation cohort (62 HCM patients, 101 non-HCM participants). External validation was performed using retrospectively collected ECG data from Xijing Hospital (3,232 HCM ECG samples from January 1st, 2000, to March 31st, 2020; 95,184 non-HCM ECG samples from January 1st to December 31st, 2020). The C-statistic was used to measure the discriminative ability of the model.

Results

Among 30 ECG features examined, all except abnormal Q wave significantly differed between the HCM patients and non-HCM comparators. After several independent feature selection approaches and model evaluation, we included only two ECG features, T wave inversion (TWI) and the amplitude of S wave in lead V1 (SV1), in the HCM prediction model. The model showed a clearly useful discriminative performance (C-statistic > 0.75) in the training [C-statistic 0.857 (0.818–0.896)], and temporal validation cohorts [C-statistic 0.871 (0.812–0.930)]. In the external validation cohort, the C-statistic of the model was 0.833 [0.825–0.841]. A browser-based calculator was generated accordingly.

Conclusion

The pragmatic model established using only TWI and SV1 may be helpful for predicting the probability of HCM and shows promise for use in population-based HCM screening.

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.

Epidemiology Characteristics and Outcome of Patients With Clinically Diagnosed Acute Myocarditis

BACKGROUND

There are controversial data regarding the outcome and management of patients hospitalized with clinically diagnosed acute myocarditis.

METHODS

We retrospectively evaluated data of 322 consecutive patients admitted to the Sheba Medical Center with clinically suspected acute myocarditis from January 2005 to December 2017. Patients were subdivided into 2 groups based on their left ventricular ejection fraction (LVEF) at presentation: 1) patients with an LVEF <50% (n = 60) and 2) patients with an LVEF ≥50% (n = 260). We aimed to evaluate the clinical characteristics, management, and in-hospital outcome as well as short-term and 1-year outcome of patients admitted with acute myocarditis.

RESULTS

The mean age of the study population was 37 ± 14 years, most of them (84%) males. Although chest pain was the main complaint in 89% of the patients at presentation, only 35% had typical pericardial pain. Patients with a LVEF <50% were more likely to demonstrate ST depression or T wave inversion on their electrocardiogram (ECG) at presentation (33% vs 18%, P = 0.007), and have higher levels of admission and peak troponin compared to those with LVEF ≥50%,(12.7 μ/L ± 15 µ/L vs 5.5 μ/L ± 9.2 μ/L, P = 0.001 for admission troponin, 18.8 μ/L ± 19.9 μ/L vs 8.4 μ/L ± 11.6 μ/L, P <0.001, for peak troponin). Univariate analysis showed that patients with an LVEF <50% were more likely to suffer from adverse cardiovascular events, defined as a composite of the following: 1) acute decompensated congestive heart failure; 2) ventricular arrhythmias; and 3) in-hospital mortality, compared to those with an LVEF ≥50% (15 [25%] vs10 [4%], P <0.001). Consistently, multivariable analysis showed that patients with an LVEF <50% had a 4-fold increased risk of adverse cardiovascular events compared to those patients with an LVEF ≥50% (heart rate [HR] = 4.30; 95% confidence interval [CI] 1.59-11.49; P <0.001).

CONCLUSIONS

Patients with clinical acute myocarditis seem to have an overall good prognosis. Although patients with an LVEF <50% are at a higher risk of in-hospital adverse events compared to those with an LVEF ≥50%, this propensity is not reflected during 1-year of follow-up.

Fragmented QRS on electrocardiography as a predictor of myocardial scar in patients with hypertrophic cardiomyopathy

Background: Fragmented QRS (fQRS) and Q waves are ECG findings in patients with myocardial scar. fQRS is more sensitive than pathological Q waves in detecting myocardial fibrosis in patients with coronary artery disease (CAD). Cardiac magnetic resonance (CMR) imaging is used for the diagnosis and for quantifying scar tissue in patients with HCM. Our aim was to correlate ECG parameters like fQRS and Q waves with the presence of late gadolinium enhancement (LGE) assessed by contrast CMR imaging to elucidate ECG markers which might predict scar tissue in HCM.Methods: This study is a retrospective analysis which included 39 patients who were diagnosed/suspected to have HCM on echocardiography and referred for contrast CMR imaging at our centre between 2010 and 2016. Presence of fQRS was correlated with scar demonstrated by LGE on CMR.Results: Twenty four (66.67%) patients had asymmetrical septal hypertrophy, 7 (19.44%) patients had apical involvement while 5 (13.89%) had concentric pattern. Only 4 (11.11%) patients had pathological Q waves in contiguous leads on surface ECG while fQRS in two contiguous leads was present in 23 (63.89%) patients. Presence of fQRS was more in patients with LGE on CMR than those without (84.61 versus 10%, p<.001). When presence of LGE in specific segments (anterior, lateral and inferior) was correlated with corresponding ECG leads, all the three segments showed significant correlation. The overall sensitivity, specificity, PPV and NPV of fQRS for predicting scar tissue were 84.6, 90.0, 95.6 and 69.2%, respectively.Conclusion: fQRS on surface ECG can be used as an indirect marker to predict the presence of fibrosis in HCM.

Electrocardiographic changes and long-term prognosis of children diagnosed with hypertrophic cardiomyopathy by the school screening program for heart disease in Japan

BACKGROUND

In Japan, the school screening program for heart disease (SS) has been performed since 1973. However, little has been reported on the electrocardiogram (ECG) changes and long-term prognosis in patients with hypertrophic cardiomyopathy (HCM) detected by the SS.

METHODS

All 44 consecutive pediatric HCM patients (10.1 ± 3.0 years old), who had been originally consulted by the SS before the diagnosis of HCM from April 1981 to April 2017, were reviewed retrospectively.

RESULTS

At the SS, all patients showed mild or no symptoms. All patients showed ECG abnormalities, and 75 % had a high proposed ECG risk score (≧6). However, 30 % of them had no echocardiogram finding of myocardial hypertrophy. During the follow-up period (14.8 ± 10.0 years), life-threatening events (LTE) occurred in 11 (25 %) patients, and the first LTE occurred during exercise in 8 (18 %). The estimated LTE and heart failure death-free survival rate at 10 years was 64.9 %. The LTE-free survival rate was lower in patients without than in those with myocardial hypertrophy at the SS.

CONCLUSIONS

The SS was useful in detecting patients with HCM with mild or no symptoms at the early stage. However, our study indicated that early detection of HCM is not associated with improvement in the prognosis of the patients. Further studies are needed.

Heart Rate and Heart Rate Variability of Rhesus Macaques (Macaca mulatta) Affected by Left Ventricular Hypertrophy

Hypertrophic cardiomyopathy (HCM) is frequently associated with sudden cardiac death, presumably due to the development of malignant arrhythmias. The risk of sudden cardiac death due to HCM has been reported to be predicted by assessing electrocardiographic (ECG) changes including frequencies and complexities of arrhythmias as well as heart rate variability (HRV) as an assessment of autonomic balance. Sudden cardiac death in association with naturally-occurring left ventricular hypertrophy (LVH) has been reported in a colony of rhesus macaques and is under investigation as a potential non-human primate model of human HCM. In the present study, 10 rhesus macaques with LVH and 10 without the signs of LVH confirmed by an echocardiographic examination were recruited for assessing ECG and HRV parameters. ECG morphology on 10-s, 6-lead ECG analysis, and the frequency and complexity of arrhythmias as well as HRV on 20-h ambulatory ECG Holter analyses were assessed. On the standard 10-s 6-lead ECG analysis, P wave and QRS complex duration as well as the QRS complex amplitude were significantly increased in the LVH-affected rhesus macaques compared to control rhesus macaques. Analysis of 20-h Holter monitoring revealed no statistically significant differences in the frequency or the complexity of arrhythmias between the LVH and the control groups. Several HRV parameters were smaller in the LVH group than the control group throughout the majority of Holter recordings showing periods of reduced variability, however, no statistically significant differences were achieved across groups and/or time points. These findings indicate that ECG analysis and Holter monitoring of rhesus macaques are feasible and that ECG morphological changes in association with LVH could be used as a possible component of an antemortem screening tool. The rhesus macaques of this study did not reveal clear indications of risk for sudden cardiac death. Further studies are necessary to determine the etiology of sudden cardiac death due in LVH affected rhesus macaques and identify if any parameters of arrhythmia assessment or HRV can be used to predict the development of sudden cardiac death.

Novel electrocardiographic features in carriers of hypertrophic cardiomyopathy causing sarcomeric mutations

OBJECTIVES

The sensitivity and specificity of the conventional 12-lead ECG to identify carriers of hypertrophic cardiomyopathy (HCM) - causing mutations without left ventricular hypertrophy (LVH) has been limited. We assessed the ability of novel electrocardiographic parameters to improve the detection of HCM mutation carriers.

METHODS

We studied 140 carriers (G+) of the TPM1-Asp175Asn or MYBPC3-Gln1061X pathogenic variants for HCM: The G+/LVH+ group (n = 98) consisted of mutation carriers with LVH and the G+/LVH- group (n = 42) without LVH. The control group consisted of 30 subjects. The standard 12-lead ECG was comprehensively analyzed and two novel ECG variables were introduced: RV1<RV2>RV3 and septal remodeling. A subset of 65 individuals underwent cardiac magnetic resonance imaging and 2D strain echocardiography.

RESULTS

Conventional major ECG criteria were sensitive (90%) and specific (97%) in identifying G+/LVH+ subjects. RV1<RV2>RV3 and septal remodeling were more prevalent in the G+/LVH- subjects compared to the control group (33% vs 3%, p = 0.005 and 45% vs 3%, p < 0.001, respectively). The combination of RV1<RV2>RV3 and Q waves and repolarization abnormalities (QR) differentiated between the G+/LVH- subjects and the control group with a sensitivity of 52% and specificity of 97%. The combination of septal remodeling and QR differentiated between G+/LVH- subjects and the control group with a sensitivity of 64% and specificity of 97%.

CONCLUSIONS

The novel ECG-parameters RV1<RV2>RV3 and septal remodeling were effective in identifying G+/LVH- subjects and could be useful in the diagnostics of new suspected HCM patients and in the screening and follow-up of HCM families.

Distinct ECG Phenotypes Identified in Hypertrophic Cardiomyopathy Using Machine Learning Associate With Arrhythmic Risk Markers

Aims: Ventricular arrhythmia triggers sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM), yet electrophysiological biomarkers are not used for risk stratification. Our aim was to identify distinct HCM phenotypes based on ECG computational analysis, and characterize differences in clinical risk factors and anatomical differences using cardiac magnetic resonance (CMR) imaging.

Methods: High-fidelity 12-lead Holter ECGs from 85 HCM patients and 38 healthy volunteers were analyzed using mathematical modeling and computational clustering to identify phenotypic subgroups. Clinical features and the extent and distribution of hypertrophy assessed by CMR were evaluated in the subgroups.

Results: QRS morphology alone was crucial to identify three HCM phenotypes with very distinct QRS patterns. Group 1 (n = 44) showed normal QRS morphology, Group 2 (n = 19) showed short R and deep S waves in V4, and Group 3 (n = 22) exhibited short R and long S waves in V4-6, and left QRS axis deviation. However, no differences in arrhythmic risk or distribution of hypertrophy were observed between these groups. Including T wave biomarkers in the clustering, four HCM phenotypes were identified: Group 1A (n = 20), with primary repolarization abnormalities showing normal QRS yet inverted T waves, Group 1B (n = 24), with normal QRS morphology and upright T waves, and Group 2 and Group 3 remaining as before, with upright T waves. Group 1A patients, with normal QRS and inverted T wave, showed increased HCM Risk-SCD scores (1A: 4.0%, 1B: 1.8%, 2: 2.1%, 3: 2.5%, p = 0.0001), and a predominance of coexisting septal and apical hypertrophy (p < 0.0001). HCM patients in Groups 2 and 3 exhibited predominantly septal hypertrophy (85 and 90%, respectively).

Conclusion: HCM patients were classified in four subgroups with distinct ECG features. Patients with primary T wave inversion not secondary to QRS abnormalities had increased HCM Risk-SCD scores and coexisting septal and apical hypertrophy, suggesting that primary T wave inversion may increase SCD risk in HCM, rather than T wave inversion secondary to depolarization abnormalities. Computational ECG phenotyping provides insight into the underlying processes captured by the ECG and has the potential to be a novel and independent factor for risk stratification.

Late Gadolinium Enhancement for Prediction of Mutation-Positive Hypertrophic Cardiomyopathy on the Basis of Panel-Wide Sequencing

BACKGROUND

Cardiac magnetic resonance (CMR) with late gadolinium enhancement (LGE) revealed a substantial variation in the extent of myocardial scarring, a pathological hallmark of hypertrophic cardiomyopathy (HCM). However, few data exist regarding the relationship between the presence of gene mutations and the extent of LGE. Therefore, we aimed to investigate whether variations in the extent of LGE in HCM patients can be explained by the presence or absence of disease-causing mutations.Methods and Results:We analyzed data from 82 unrelated HCM patients who underwent both LGE-CMR and next-generation sequencing. We identified disease-causing sarcomere gene mutations in 44 cases (54%). The extent of LGE on CMR was an independent factor for predicting mutation-positive HCM (odds ratio 2.12 [95% confidence interval 1.51-3.83], P<0.01). The area under the curve of %LGE was greater than that of the conventional Toronto score for predicting the presence of a mutation (0.96 vs. 0.69, P<0.01). Sensitivity, specificity, positive predictive value, and negative predictive value of %LGE (cutoff >8.1%) were 93.2%, 89.5%, 91.1%, and 91.9%, respectively.

CONCLUSIONS

The results demonstrated that %LGE clearly discriminated mutation-positive from mutation-negative HCM in a clinically affected HCM population. HCM with few or no myocardial scars may be genetically different from HCM with a higher incidence of myocardial scars.

Prognostic Value of Cardiac Magnetic Resonance Tissue Characterization in Risk Stratifying Patients With Suspected Myocarditis

BACKGROUND

Diagnosing myocarditis is challenged by nonspecific clinical signs and symptoms and low accuracy of endomyocardial biopsy. Cardiac magnetic resonance imaging (CMR) provides both cardiac anatomy and tissue characterization in this setting, but the prognostic value of this method as a primary assessment tool in patients with suspected myocarditis remains limited.

OBJECTIVES

This study sought to determine cardiac event-free survival of a consecutive cohort with suspected myocarditis with regard to CMR findings.

METHODS

Six hundred seventy patients with suspected myocarditis underwent CMR including late gadolinium enhancement (LGE) parameters between 2002 and 2015 and were included and followed. We performed multivariable model for major adverse cardiovascular events (MACE) and determined the continuous net reclassification improvement by LGE markers.

RESULTS

At a median follow-up of 4.7 years (interquartile range [IQR]: 2.3 to 7.3 years), 98 patients experienced a MACE. Two hundred ninety-four (44%) patients showed LGE presence, which was associated with a more than doubling risk of MACE (hazard ratio [HR]: 2.22; 95% confidence interval [CI]: 1.47 to 3.35; p < 0.001). Annualized MACE rates were 4.8% and 2.1% corresponding to LGE presence and absence, respectively (p < 0.001). In the multivariable model, LGE presence maintained significant association with MACE (HR: 1.72; 95% CI: 1.08 to 2.76; p = 0.023). The computed continuous net reclassification improvement was 0.39 (95% CI: 0.10 to 0.67) when LGE presence was added to the multivariable model for MACE. Regarding location and pattern, septal and midwall LGE showed strongest associations with MACE (HR: 2.55; 95% CI: 1.77 to 3.83 and HR: 2.39; 95% CI: 1.54 to 3.69, respectively; both p < 0.001). A patchy distribution portended to a near 3-fold increased hazard to MACE (HR: 2.93; 95% CI: 1.79 to 4.80; p < 0.001). LGE extent (per 10% increase) corresponded to a 79% increase in risk of MACE (HR: 1.79; 95% CI: 1.25 to 2.57; p = 0.002). A normal CMR study corresponded to low annual MACE and death rates of 0.8% and 0.3%, respectively.

CONCLUSIONS

CMR tissue characterization provides effective risk stratification in patients with suspected myocarditis.

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.

Usefulness of Electrocardiographic Patterns at Presentation to Predict Long-term Risk of Cardiac Death in Patients With Hypertrophic Cardiomyopathy

The objective of this study was to investigate the prognostic significance of 12-lead electrocardiogram (ECG) patterns in a large multicenter cohort of patients with hypertrophic cardiomyopathy; 1,004 consecutive patients with hypertrophic cardiomyopathy and a recorded standard ECG (64% men, mean age 50 ± 16 years) were evaluated at 4 Italian centers. The study end points were sudden cardiac death (SCD) or surrogates, including appropriate implanted cardiac defibrillator discharge and resuscitated cardiac arrest and major cardiovascular events (including SCD or surrogates and death due to heart failure, cardioembolic stroke, or heart transplantation). Prevalence of baseline electrocardiographic characteristics was: normal ECG 4%, ST-segment depression 56%, pseudonecrosis waves 33%, "pseudo-ST-segment elevation myocardial infarction (STEMI)" pattern 17%, QRS duration ≥120 ms 17%, giant inverted T waves 6%, and low QRS voltages 3%. During a mean follow-up of 7.4 ± 6.8 years, 77 patients experienced SCD or surrogates and 154 patients experienced major cardiovascular events. Independent predictors of SCD or surrogates were unexplained syncope (hazard ratio [HR] 2.5, 95% confidence interval [CI] 1.4 to 4.5, p = 0.003), left ventricular ejection fraction <50% (HR 3.5, 95% CI 1.9 to 6.7, p = 0.0001), nonsustained ventricular tachycardia (HR 1.7, 95% CI 1.1 to 2.6, p = 0.027), pseudo-STEMI pattern (HR 2.3, 95% CI 1.4 to 3.8, p = 0.001), QRS duration ≥120 ms (HR 1.8, 95% CI 1.1 to 3.0, p = 0.033), and low QRS voltages (HR 2.3, 95% CI 1.01 to 5.1, p = 0.048). Independent predictors of major cardiovascular events were age (HR 1.02, 95% CI 1.01 to 1.03, p = 0.0001), LV ejection fraction <50% (HR 3.73, 95% CI 2.39 to 5.83, p = 0.0001), pseudo-STEMI pattern (HR 1.66, 95% CI 1.13 to 2.45, p = 0.010), QRS duration ≥120 ms (HR 1.69, 95% CI 1.16 to 2.47, p = 0.007), and prolonged QTc interval (HR 1.68, 95% CI 1.21 to 2.34, p = 0.002). In conclusion, a detailed qualitative and quantitative electrocardiographic analyses provide independent predictors of prognosis that could be integrated with the available score systems to improve the power of the current model.

Usefulness of Electrocardiographic Voltage to Determine Myocardial Fibrosis in Hypertrophic Cardiomyopathy

Classic electrocardiographic (ECG) voltage indexes have been applied to screen for left ventricular (LV) hypertrophy in hypertrophic cardiomyopathy (HC). However, it is unclear whether low ECG voltage reflects deteriorated electrical forces because of replacement of the myocardium by fibrotic tissues in HC. We investigated correlations between classic ECG voltage indexes (Cornell, total QRS voltage, and Sokolow-Lyon) and cardiac magnetic resonance (CMR) parameters focusing on the impact of low ECG voltage on the LV ejection fraction (LVEF) and myocardial fibrosis in HC. We studied 108 consecutive patients with HC who underwent CMR imaging with late gadolinium enhancement (LGE). Nineteen patients with complete right or left bundle branch block were excluded, leaving 89 patients for analysis (age 61.0 ± 13.9 years; 58 men). Of the 3 voltage indexes, the total QRS voltage and Sokolow-Lyon indexes were positively correlated with LVEF. For discriminating patients with end-stage HC (LVEF <50%) from patients with HC and preserved LVEF (≥ 50%), receiver-operating characteristic analysis revealed an excellent area under the curve of 0.87 for the total QRS voltage index and 0.90 for the Sokolow-Lyon index, whereas the area under the curve for the Cornell index was only 0.54 (p <0.01). Moreover, these 2 voltage indexes were negatively correlated with the extent of LGE-determined myocardial fibrosis when adjusted by the LV maximal wall thickness. In conclusion, low ECG voltage indexes may reflect increased myocardial fibrosis in patients with HC.

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.

Correlation of precordial voltages to left ventricular mass on echocardiogram in adolescent patients with hypertrophic cardiomyopathy compared with that in adolescent athletes

Electrocardiograms continue to be part of screening programs for athletes and familial hypertrophic cardiomyopathy (HC). Whether electrocardiographic (ECG) findings of left ventricular (LV) hypertrophy can distinguish between healthy populations and those with HC remains unclear. We sought to (1) analyze the relation between ECG voltage and LV mass in patients with HC and (2) evaluate ECG characteristics of patients with phenotypical HC. Retrospective cohort of patients with HC aged 13 to 18 years. Relation between ECG voltages (RV6, SV1, and RV6 + SV1) and echocardiogram measurements of LV mass was investigated using smoothing splines to display relations and compared with those in a prospectively obtained population of adolescents. Frequency of abnormal LV voltages and nonvoltage ECG changes (Q waves, T-wave changes, and ST changes) were analyzed for association with HC. Fifty-three patients with HC (72% men) were age and gender matched to 104 control patients. Smoothing splines demonstrated that parabolic rather than linear relations existed between LV mass and SV1, RV6, and RV6 + SV1 in patients with HC and not the control cohort. LV hypertrophy by ECG voltage criteria was present in 34% of patients with HC and associated with poor sensitivity (29%). In patients with HC, 56% demonstrated nonvoltage ECG abnormalities and were associated with improved sensitivity (68%) and high specificity (94%). In conclusion, there is a parabolic relation between LV voltages and LV mass in adolescents with HC that may lead to "pseudonormalization." Voltage abnormalities were associated with poor sensitivity, whereas nonvoltage criteria were associated with improved sensitivity with high specificity.

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.

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.

ECG characteristics according to the presence of late gadolinium enhancement on cardiac MRI in hypertrophic cardiomyopathy

BACKGROUND

Late gadolinium enhancement (LGE) on cardiac MRI (CMR) has been described as an independent predictive factor of cardiovascular events among patients with hypertrophic cardiomyopathy (HCM). LGE and Q waves are considered as myocardial scar markers but their relation in the context of HCM is poorly established and has to be more supported. The objective of the study was to compare ECG findings in the presence or absence of LGE.

METHODS

42 patients with HCM confirmed by CMR were included in the study. ECG abnormalities including abnormal Q waves and five ECG scores of left ventricular hypertrophy were assessed and compared according to LGE presence and its extension. Some CMR features, such as septal to posterior wall thickness ratio, were also studied according to the presence of LGE and the presence of abnormal Q waves.

RESULTS

Abnormal Q waves were more prevalent in the LGE (+) group (60% vs 12%; p=0.002), but there was no correlation between location of Q waves on ECG and territory of LGE on CMR. Among patients with LGE, quantitative analysis of LGE was not different in the presence or absence of Q waves. In contrast to the LGE mass, septal to posterior wall thickness was higher in patients with abnormal Q waves (2.3±0.7 vs 1.6±0.5; p=0.012).

CONCLUSIONS

Although abnormal Q waves were more prevalent in the presence of LGE, no correlation was found with the LGE location and extent. These data suggest that abnormal electrical activation of the hypertrophied ventricular septum represented by a high septal to posterior wall thickness ratio seems to be an important mechanism of abnormal Q waves in HCM.

Current perspectives in genetic cardiovascular disorders: from basic to clinical aspects

We summarize recent advances in the clinical genetics of hypercholesterolemia, hypertrophic cardiomyopathy (HCM), and lethal arrhythmia, all of which are monogenic cardiovascular diseases being essential to understanding the heart and circulatory pathophysiology. Among the issues of hypercholesterolemia which play a pivotal role in development of vascular damages, familial hypercholesterolemia is the common genetic cardiovascular disease; in addition to identifying the gene mutation coding low-density lipoprotein receptor, lipid kinetics in autosomal recessive hypercholesterolemia as well as in proprotein convertase subtilisin/kexin 9 gene mutation were recently demonstrated. As for HCM, some gene mutations were identified to correlate with clinical manifestations. Additionally, a gene polymorphism of the renin-angiotensin system in development of heart failure was identified as a modifier gene. The lethal arrhythmias such as sudden death syndromes, QT prolongation, and Brugada syndrome were found to exhibit gene mutation coding potassium and/or sodium ion channels. Interestingly, functional analysis of these gene mutations helped to identify the role of each gene mutation in developing these cardiovascular disorders. We suggest considering the genetic mechanisms of cardiovascular diseases associated with hyperlipidemia, myocardial hypertrophy, or lethal arrhythmia in terms of not only clinical diagnosis but also understanding pathophysiology of each disease with therapeutic aspects.

Electrocardiogram screening for disorders that cause sudden cardiac death in asymptomatic children: a meta-analysis

BACKGROUND AND OBJECTIVES

Pediatric sudden cardiac death (SCD) occurs in an estimated 0.8 to 6.2 per 100 000 children annually. Screening for cardiac disorders causing SCD in asymptomatic children has public appeal because of its apparent potential to avert tragedy; however, performance of the electrocardiogram (ECG) as a screening tool is unknown. We estimated (1) phenotypic (ECG- or echocardiogram [ECHO]-based) prevalence of selected pediatric disorders associated with SCD, and (2) sensitivity, specificity, and predictive value of ECG, alone or with ECHO.

METHODS

We systematically reviewed literature on hypertrophic cardiomyopathy (HCM), long QT syndrome (LQTS), and Wolff-Parkinson-White syndrome, the 3 most common disorders associated with SCD and detectable by ECG.

RESULTS

We identified and screened 6954 abstracts, yielding 396 articles, and extracted data from 30. Summary phenotypic prevalences per 100 000 asymptomatic children were 45 (95% confidence interval [CI]: 10-79) for HCM, 7 (95% CI: 0-14) for LQTS, and 136 (95% CI: 55-218) for Wolff-Parkinson-White. The areas under the receiver operating characteristic curves for ECG were 0.91 for detecting HCM and 0.92 for LQTS. The negative predictive value of detecting either HCM or LQTS by using ECG was high; however, the positive predictive value varied by different sensitivity and specificity cut-points and the true prevalence of the conditions.

CONCLUSIONS

Results provide an evidence base for evaluating pediatric screening for these disorders. ECG, alone or with ECHO, was a sensitive test for mass screening and negative predictive value was high, but positive predictive value and false-positive rates varied.

Hypertrophic cardiomyopathy and sudden cardiac death

Hypertrophic cardiomyopathy (HCM) is a common genetic cardiovascular disease that affects the left ventricle. HCM can appear at any age, with the majority of the patients remaining clinically stable. When patients complain of symptoms, these include: dyspnea, dizziness, syncope and angina. HCM can lead to sudden cardiac death (SCD), mainly due to ventricular tachyarrhythmia or ventricular tachycardia. High-risk patients benefit from implantable cardioverter-defibrillators. Left ventricular outflow tract obstruction is not a rare feature in HCM, especially in symptomatic patients, and procedures that abolish that obstruction provide positive and consistent results that can improve long-term survival. HCM is the most common cause of sudden death in young competitive athletes and preparticipation screening programs have to be implemented to avoid these tragic fatalities. The structure of these programs is a matter of large debate. Worldwide registries are necessary to identify the full extent of HCM-related SCD.

Usefulness of hydrophilic vs lipophilic statins after acute myocardial infarction: subanalysis of MUSASHI-AMI

BACKGROUND

Statins are widely used to reduce blood levels of low-density lipoprotein-cholesterol (LDL-C). Each statin has unique pharmacokinetic properties; lipophilicity is one such property and relates to tissue selectivity.

METHODS AND RESULTS

The Multicenter Study for Aggressive Lipid-lowering Strategy by HMG-CoA Reductase Inhibitors in Patients with Acute Myocardial Infarction (MUSASHI-AMI) trial evaluated the effect of discretional statin treatment initiated within 96 h after onset of acute myocardial infarction (AMI) in Japanese patients. To clarify whether statin lipophilicity affects prognosis, a post hoc analysis of the MUSASHI-AMI database was performed. Patients who were assigned to receive statin were separated into 2 groups according to the lipophilicity of the statins they were administered: lipophilic statins (atorvastatin, fluvastatin, pitavastatin and simvastatin; LS group; n=131) or hydrophilic statins (pravastatin; HS group; n=110). There was no difference in baseline LDL-C concentrations between the 2 groups. Although LDL-C was decreased more potently in the LS than HS groups (-34% vs -19%; p=0.0069), acute coronary syndrome events tended to occur less frequently (3.6% vs 9.9%; p=0.0530) and the incidence of new Q-wave appearance in electrocardiogram was significantly lower (75% vs 89%; p=0.0056) in the HS than LS groups.

CONCLUSIONS

In normocholesterolemic Japanese patients after AMI, hydrophilic pravastatin could be superior to lipophilic statins at preventing new Q-wave appearance and reducing cardiovascular events.

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

Differences in the diagnostic value of a variety of definitions of negative T waves for HCM (hypertrophic cardiomyopathy) have not yet been clarified, resulting in a number of definitions being applied in previous studies. The aim of the present study was to determine the most accurate diagnostic definition of negative T waves for HCM in genotyped populations. Electrocardiographic and echocardiographic findings were analysed in 161 genotyped subjects (97 carriers and 64 non-carriers). We applied three different criteria that have been used in previous studies: Criterion 1, negative T wave >10 mm in depth in any leads; Criterion 2, negative T wave >3 mm in depth in at least two leads; and Criterion 3, negative T wave >1 mm in depth in at least two leads. Of the three criteria, Criterion 3 had the highest sensitivity (43% compared with 5 and 26% in Criterion 1 and Criterion 2 respectively; P<0.0001) and retained a specificity of 95%, resulting in the highest accuracy. In comparison with abnormal Q waves, negative T waves for Criterion 3 had a lower sensitivity in detecting carriers without LVH (left ventricular hypertrophy) (12.9% for negative T waves compared with 22.6% for abnormal Q waves). On the other hand, in detecting carriers with LVH, the sensitivity of negative T waves increased in a stepwise direction with the increasing extent of LVH (P<0.001), whereas there was less association between the sensitivity of abnormal Q waves and the extent of LVH. In conclusion, Criterion 3 for negative T waves may be the most accurate definition of HCM based on genetic diagnoses. Negative T waves may show different diagnostic value according to the different criteria and phenotypes in genotyped populations with HCM.

Hypertrophic cardiomyopathy: electrocardiographic manifestations and other important considerations for the emergency physician

Hypertrophic cardiomyopathy (HCM) is one of the most common inherited primary cardiac disorders and the most common cause of sudden cardiac death in young athletes. With advances in technology, it is now recognized that HCM affects individuals of all ages. Many patients with HCM will have a benign course with few symptoms. Some patients, however, possess risk factors that greatly increase the likelihood of sudden death if their disease remains undiagnosed. Therefore, it is imperative that emergency physicians be familiar with the symptoms and typical electrocardiogram manifestations of HCM. Three illustrative cases are presented with a review of the disease.

Diastolic dysfunction without left ventricular hypertrophy is an early finding in children with hypertrophic cardiomyopathy-causing mutations in the beta-myosin heavy chain, alpha-tropomyosin, and myosin-binding protein C genes

OBJECTIVES

We investigated the presence of left ventricular hypertrophy (LVH) and features of diastolic dysfunction in genotype-confirmed children from families with hypertrophic cardiomyopathy (HCM) and healthy control children.

BACKGROUND

In subjects with HCM-causing mutations, LVH usually does not evolve until adolescence. Diastolic dysfunction has not been systematically evaluated in children carrying HCM-causing mutations.

METHODS

All children (aged 1.5-16.7 years) from 14 HCM families with identified disease-causing mutations (the Arg719Trp mutation in the beta-myosin heavy chain gene [MYH7], the Asp175Asn mutation in the alpha-tropomyosin gene [TPM1], the Gln1061X mutation in the myosin-binding protein C gene [MYBPC3], and the IVS5-2A-->C mutation in the MYBPC3 gene) and 53 matched control children were examined with electrocardiography and 2- and 3-dimensional echocardiography (2DE and 3DE). Natriuretic peptides were measured in children from HCM families and 67 control children.

RESULTS

Of 53 children from HCM families, 27 (51%) had a disease-causing mutation (G+). G+ children had slightly thicker septum on 2DE compared with the control children (P = .004), but only 3 (11%) of 27 G+ children exceeded the 95th percentile values of the body surface area-adjusted maximal LV thickness of healthy children (the major echocardiographic criterion for HCM). However, prolonged isovolumetric relaxation time, increased left atrial volume on 3DE, or increased levels of NT-proANP, all features suggestive of diastolic dysfunction, were found in 14 (52%) of 27 G+ children.

CONCLUSIONS

In children with HCM-causing mutations, signs of diastolic dysfunction are found in about half of the cases, as LVH is present only in small percentage of these children.

Utility of cardiac magnetic resonance imaging in the diagnosis of hypertrophic cardiomyopathy

BACKGROUND

Two-dimensional echocardiography is currently the standard test for the clinical diagnosis of hypertrophic cardiomyopathy (HCM). The present study was undertaken to determine whether cardiac MRI (CMR) affords greater accuracy than echocardiography in establishing the diagnosis and assessing the magnitude of left ventricular (LV) hypertrophy in HCM.

METHODS AND RESULTS

Forty-eight patients (age 34+/-16 years) suspected of having HCM (or with a confirmed diagnosis) were imaged by both echocardiography and CMR to assess LV wall thickness in 8 anatomic segments (total n=384 segments) and compared in a blinded fashion. Maximum LV thickness was similar by echocardiography (21.7+/-9.1 mm) and CMR (22.5+/-9.6 mm; P=0.21). However, in 3 (6%) of the 48 patients, echocardiography did not demonstrate LV hypertrophy, and CMR identified otherwise undetected areas of wall thickening in the anterolateral LV free wall (17 to 20 mm), which resulted in a new diagnosis of HCM. In the overall study group, compared with CMR, echocardiography also underestimated the magnitude of hypertrophy in the basal anterolateral free wall (by 20+/-6%; P=0.001), as well as the presence of extreme LV wall thickness (> or =30 mm) in 10% of patients (P<0.05).

CONCLUSIONS

CMR is capable of identifying regions of LV hypertrophy not readily recognized by echocardiography and was solely responsible for diagnosis of the HCM phenotype in an important minority of patients. CMR enhances the assessment of LV hypertrophy, particularly in the anterolateral LV free wall, and represents a powerful supplemental imaging test with distinct diagnostic advantages for selected HCM patients.

A novel mutation in the cardiac myosin-binding protein C gene is responsible for hypertrophic cardiomyopathy with severe ventricular hypertrophy and sudden death

It has been demonstrated previously that clinical phenotypes of HCM (hypertrophic cardiomyopathy) caused by mutations in the cardiac MyBP-C (myosin-binding protein C) gene show late onset, low penetrance and favourable clinical course. However, we have encountered severe phenotypes in several carriers of the MyBP-C gene mutations. The aim of the present study was to screen novel MyBP-C gene mutations in patients with HCM and to investigate the genetic differences in affected subjects with severe phenotypes. The MyBP-C gene was screened in 292 Japanese probands with HCM, and a novel c.2067+1G→A mutation was present in 15 subjects in five families. Clinical phenotypes of carriers of the c.2067+1G→A mutation were compared with those of a previously identified Arg820Gln (Arg820→Gln) mutation in the MyBP-C gene. The disease penetrance in subjects aged ≥30 years was 90% in carriers of the c.2067+1G→A mutation and 61% in carriers of the Arg820Gln mutation. Sudden death occurred in four subjects from three families with the c.2067+1G→A mutation and in two subjects from one family with the Arg820Gln mutation. Two carriers of the c.2067+1G→A mutation had substantial hypertrophy (maximal wall thickness ≥30 mm). In contrast, two carriers of the Arg820Gln mutation had end-stage HCM. In conclusion, the c.2067+1G→A mutation is associated with HCM with substantial hypertrophy and moderate incidence of sudden death, whereas the Arg820Gln mutation is associated with end-stage HCM. These observations may provide important prognostic information regarding the clinical practice of HCM.

Differences in diagnostic value of four electrocardiographic voltage criteria for hypertrophic cardiomyopathy in a genotyped population

The diagnostic value of various classic electrocardiographic (ECG) voltage criteria for hypertrophic cardiomyopathy (HC) has not been established in a genotyped population. This study aimed to determine the most accurate diagnostic definition of classic ECG voltage criteria for detecting carriers of HC. ECG and echocardiographic findings were analyzed in 161 genotyped subjects (97 genetically affected, 64 unaffected) from 20 families with disease-causing mutations in 4 genes. The diagnostic value of 4 voltage criteria (Cornell, Sokolow-Lyon, Romhilt-Estes, and 12-lead QRS voltage) for detecting carriers of HC was investigated. In all subjects, the Romhilt-Estes (point score > or =4) criterion and 12-lead QRS voltage (> or =240 mm) were most sensitive (37% and 36%, respectively), with high specificity (95% each), resulting in the greatest accuracy (60% and 59%, respectively). Using these criteria, in subjects without echocardiographic evidence of left ventricular hypertrophy, voltage abnormalities were found in 22.6% of carriers and 4.7% of noncarriers (p <0.01). In conclusion, these findings suggest that the Romhilt-Estes and the 12-lead QRS voltage criteria may be the most accurate diagnostic definitions for HC on the basis of molecular genetic diagnoses. Furthermore, this study demonstrated that voltage abnormalities may be found in prehypertrophic carriers. Even when genetic testing becomes widely available, it will be difficult to make genetic diagnoses in all patients with HC because of its genetic heterogeneity. Therefore, understanding the diagnostic value of classic ECG voltage criteria may be important in detecting carriers, including those without left ventricular hypertrophy.

Phenotypic differences between electrocardiographic and echocardiographic determination of hypertrophic cardiomyopathy in genetically affected subjects

OBJECTIVES

In the molecular era, two types of phenotypic differences are recognized between electrocardiography (ECG) and echocardiography in hypertrophic cardiomyopathy (HCM); ECG abnormalities in carriers without left ventricular hypertrophy (LVH), and normal ECG patterns in carriers with LVH. The goal of this study was to evaluate the diagnostic value of ECG for detecting carriers without LVH, and also to assess normal ECG patterns in carriers with LVH from the genetic standpoint of HCM.

SETTING

A matched case-control study in a university hospital and general hospitals in Japan.

PATIENTS AND DESIGN

ECG and echocardiographic findings were analysed in 173 genotyped subjects (107 genetically affected, 66 unaffected) from families with disease-causing mutations in four genes.

RESULTS

ECG abnormalities were found in 18 (54.5%) of 33 nonhypertrophic carriers, but only nine (13.6%) of 66 noncarriers (P < 0.001). For detecting nonhypertrophic carriers, ST-T abnormalities showed the highest accuracy amongst the three major ECG criteria. In contrast, normal ECG patterns were found in eight (10.8%) of 74 carriers with LVH. The sensitivity of ECG for detecting carriers with LVH in families with the cardiac myosin-binding protein C, cardiac troponin T and cardiac troponin I gene mutations was 83%, 88% and 94% respectively.

CONCLUSION

These findings suggest that ECG may have favourable diagnostic value even for detecting nonhypertrophic carriers. Furthermore, diagnostic value of ECG may differ according to the genes involved. Our data may contribute to interpretation of phenotypic differences between ECG and echocardiography from the viewpoint of molecular genetics of HCM.

Management of pediatric hypertrophic cardiomyopathy

PURPOSE OF REVIEW

As the underlying genetic basis of hypertrophic cardiomyopathy is being characterized, there has been increasing recognition of the wide spectrum and variable evolution of this disease within the pediatric age range. This review outlines recent evidence relevant to the diagnosis, management, and prognosis of hypertrophic cardiomyopathy specific to children and adolescents.

RECENT FINDINGS

Studies of putative causal genes are leading to the discovery of factors affecting the variability of phenotypic expression and possible avenues for new therapies. Nonetheless, the use of genetic testing currently remains for research purposes only. Echocardiography is the primary means for evaluation, with an increasing focus on diastolic performance. Useful prognostic information can be obtained from the safe performance of cardiopulmonary stress testing. Sudden death can occur in children, although the risk factors are likely different than in adults. The role and mechanisms for possible ischemia remain controversial, and likely differ between individuals. Activity restrictions are recommended, with medical therapy reserved for those who are symptomatic. For those with important left ventricular outflow obstruction, surgical myectomy may be indicated, with little current role for alcohol septal ablation. Advances in implantable defibrillators now make this therapy feasible in younger children.

SUMMARY

There are important differences from adults in the approach to the diagnosis and management of hypertrophic cardiomyopathy in children and adolescents. Care regarding prognostication and therapy must be taken given the potential life-long implications.