Hypertrophic cardiomyopathy and atrial fibrillation: the Cardiomyopathy/Myocarditis registry of the EURObservational Research Programme of the European Society of Cardiology

Background

Current guidelines for AF management underline a complex approach to detecting and treating atrial fibrillation (AF). Hypertrophic cardiomyopathy (HCM) is commonly associated with AF.

Purpose

To assess the clinical characteristic and prognosis in patients with HCM and AF.

Methods and results

Overall, 1739 adult patients with HCM (711/40.9% female; median age at diagnosis: 55.5 years) were enrolled in the EURObservational Research Programme – Cardiomyopathy/Myocarditis Long-Term Registry. Baseline clinical characteristics and adverse cardiovascular endpoints at 1-year follow-up were analysed.

Results

At baseline, AF was found in 478 (27.5%) subjects (paroxysmal: 54.7%, persistent: 17.6%, permanent: 27.7%). Newly diagnosed AF was identified during 1-year follow-up in 48 (2.8%) subjects with HCM.

The presence of AF was associated with higher age (59.6±13.8 vs 50.8±16.1, p<0.001); BMI (27.7±5.1 vs 26.6±4.6 kg/m2, p<0.001); more advanced NYHA class (NYHA I/II and III/IV: 75.1 and 24.9 vs 86.2 and 13.8%, p<0.001); more frequent history of diabetes (14.6 vs 8.4%, p<0.001); arterial hypertension 43.4 vs 34.6%, p<0.001); renal impairment (15.4 vs 6.35%, p<0.001); and history of sustained VT (10.8 vs 6.35%, p<0.001). AF patients were characterized by lower left ventricular ejection fraction (LV EF) (59±12 vs 63±11%, P<0.001), left atrium (LA) dilatation (48.9±9.1 vs 42.4±7.7%, p<0.001), increased pulmonary artery systolic pressure (37.8±13.7 vs 29.6±12.6 mmHg, p<0.001), distribution of LV hypertrophy (p=0.032) and more advanced LV diastolic dysfunction (p<0.001).

On multivariate logistic regression analysis, independent predictors of AF in the HCM population were: age at enrolment (OR 1.068, P<0.001); LVEF (OR 0.978, p<0.001); and LA diameter (OR 1.094, p<0.001).

Oral anticoagulation (OAC) was administered in 69.5% of patients with AF (vitamin K antagonist: 48.5%; direct OAC: 21%). ICD was implanted in 26.8% in AF and 16.9% in non-AF subjects (p<0.001). PVI was performed in 9.9% of AF patients only.

The annual incidence of stroke/TIA was higher in AF than in the non-AF population (2.64 vs 0.85%, p=0.009). There was a trend towards increased death from any cause in the AF population (3.39 vs 1.74%, p=0.05). There were no differences in SCD-risk score between AF and non-AF subjects.

Conclusion

The study reveals a high prevalence of AF in patients with HCM that corresponds with more advanced symptoms, increased prevalence of comorbidities, structural and functional heart remodelling along with inadequate anticoagulation and a significant increase in the risk of stroke. The clinical characteristics of HCM-AF patients indicate that the ESC recommended complex AF approach “CC To ABC” is appropriate in this population.

Funding Acknowledgement

Type of funding sources: None.

Clinical characterisation of hypertrophic cardiomyopathy caused by MYH7 gene variants in children

Background

Variants in the cardiac Beta Myosin Heavy chain 7 gene (MYH7) are a common cause of hypertrophic cardiomyopathy (HCM) in adults, but their role in paediatric-onset HCM has not been systematically characterised. This study aims to describe the presentation, clinical characteristics and outcomes of childhood HCM secondary to disease-causing MYH7 variants.

Methods

Retrospective, longitudinal, data from 70 individuals meeting diagnostic criteria for HCM under the age of 18 years with disease-causing MYH7 variants from a single specialist centre (1991–2019) were collected. A Major Adverse Cardiac Event was defined as sudden cardiac death (SCD), heart failure-related death, cardiac transplantation, haemodynamically-compromising sustained ventricular arrhythmia or appropriate implantable cardioverter defibrillator (ICD) therapy.

Results

Median age at diagnosis was 9.2 years (IQR 4.2–13.3 years); 47 patients (67.1%) were less than 12 years and 7 (10.0%) were under the age of 1 at diagnosis. Twenty-two patients (31.4%) were probands. MYH7 variants were missense (n=67) or truncating (n=1). Reason for presentation were: family screening (n=45, 64.3%); cardiac symptoms (n=12, 17.1%); incidental finding (n=11, 15.7%); and out of hospital cardiac arrest (n=2, 2.9%). At baseline, mean maximum left ventricular wall thickness (MLVWT) z-score was 9.6 (±5.8), 11 patients (15.7%) had resting left ventricular outflow tract obstruction (left ventricular outflow tract gradient ≥30mmHg). Baseline phenotype did not significantly differ between probands and non-probands (MLVWT Z score 11.9 (±4.5) vs 8.5 (±6.1), p-value 0.0675). Over a median follow up of 3.6 years (IQR 1.8–7.9 years), 10 patients (14.3%) underwent a left ventricular septal myectomy at a median age 6.4 years (IQR 3.4–12.1 years) and 27 (38.6%) had an implantable cardioverter defibrillator (ICD) for primary (n=24, 34.3%) or secondary (n=3, 4.3%) prevention. Three patients (4.3%) died (SCD, n=1; heart-failure related, n=1; non-cardiac, n=1) and 3 (4.3%) underwent cardiac transplantation. Ten patients (14.3%) experienced a MACE. Patients who experienced a MACE were more likely to be probands [n= 6 (60.0%) vs n=16 (26.7%); p=0.036] but did not differ in terms of baseline phenotype (p=0.134).

Conclusion

MYH7 variants can cause infantile and childhood-onset disease, which is associated with significant early cardiac morbidity and mortality. Adverse outcomes were more common in those presenting as probands.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Medical Research Council, Great Ormond Street Hospital charity.

Clinical features and natural history of RASopathy-associated hypertrophic cardiomyopathy in children

Background

The RASopathies are a group of genetic disorders caused by germline mutations in genes encoding components of the RAS/MAPK signalling pathway and frequently associated with hypertrophic cardiomyopathy (HCM). The clinical features and outcomes of RASopathy-related HCM are incompletely understood and most published studies are limited by relatively small numbers and incomplete clinical characterisation.

Purpose

To describe the clinical features outcomes in a large, single-centre cohort of patients with RASopathy-associated HCM diagnosed <18 years.

Methods

Data from 105 patients [68 (64.8%) males] diagnosed in childhood with RASopathy-associated HCM at a single specialist centre between 1985 and 2020 were retrospectively analysed.

Results

The RASopathy diagnosis was Noonan syndrome in 69 patients (65.7%); NSML in 10 (9.5%); CFC in 6 (5.7%); Costello in 5 (4.8%) and 15 patients (14.2%) had another Noonan-like variant. 72 patients (68.6%) had a pathogenic/likely pathogenic variant in a RAS-MAPK gene, most commonly PTPN11 [n=25 (34.7%)], followed by RAF 1 [n=13 (18.1%)]. 100 patients (95.2%) were probands, 9 (8.6%) had family history of cardiomyopathy and 2 (1.9%) family history of sudden cardiac death (SCD). 52 (49.5%) had concomitant congenital heart defects (CHD) [ASD 13 (25%), VSD 6 (11.5%), PDA 1 (1.9%), >1 CHD 32 (61.5%)]. 29 (27.6%) had symptoms at baseline assessment and 56 (53.3%) were on cardiac medication. The distribution of left ventricular hypertrophy (LVH) was concentric in 47 (44.7%); 32 (30.5%) had asymmetric septal hypertrophy (ASH), and undocumented in 25 patients (23.8%). 45 patients (42.9%) had biventricular hypertrophy (BVH). Resting left ventricular outflow tract obstruction (LVOTO) was present in 39 (37.1%) with haemodynamically significant LVOTO (≥50mmHg) in 23 (21.9%). Resting right ventricular outflow tract obstruction (RVOTO) was present in 21 (20%). Over a median follow up time of 6 years, 19 patients (18.1%) died [1 (5.3%) SCD; 2 (10.5%) due to Heart Failure-related death; 1 (5.3%) due to another CVS cause; 5 (26.3%) due to a non-CVS cause and for 10 (52.6%) cause of death was unknown]. Incidence rate of death was calculated at 2.7 deaths per 100 person-years. Surgical septal myectomy was performed in 9 patients (8.6%) and 3 (2.9%) underwent cardiac transplantation. 14 patients (13.3%) suffered arrhythmic events [atrial tachycardia 6 (42.9%), Non-Sustained Ventricular Tachycardia 4 (3.8%), and Ventricular Tachycardia/Ventricular Fibrillation 4 (3.8%)].

Conclusion

To our knowledge, this is the largest cohort of RASopathy-associated HCM. The findings show a heterogeneous clinical presentation with a high prevalence of morbidity and mortality. Further work is needed to determine predictors of outcome in this population.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Onassis Foundation

Clinical characteristics and natural history of pre-adolescent non-syndromic hypertrophic cardiomyopathy

Background

The clinical presentation and natural history of pre-adolescent sarcomeric hypertrophic cardiomyopathy (HCM) has not been systematically characterised. The aim of this study was to describe the clinical characteristics and outcomes of a large, international, multicentre cohort of children diagnosed with non-syndromic HCM below the age of 12.

Methods

Data from the International Paediatric Hypertrophic Cardiomyopathy Consortium on 639 children meeting diagnostic criteria for HCM below 12 years of age (pre-adolescent) were collected and compared with 568 diagnosed aged 12–16 years. Patients with syndromic and metabolic HCM were excluded.

Results

Of 639 (male n=417, 65.3%) children with pre-adolescent HCM, 339 (53.1%) had a family history of HCM and 57 (8.9%) a family history of sudden cardiac death (SCD). At the time of baseline assessment; 132 (20.7%) had heart failure symptoms and 39 (6.1%) reported unexplained syncope. Median maximal left ventricular wall thickness on echocardiogram was 13.6mm (IQR 10–19) with a corresponding median z-score of 8.7 (5.3–14.4). 145 (22.7%) had left ventricular outflow tract obstruction (LVOTO) (maximal LVOT gradient≥30mmHg) and 35 (5.5%) had severe LVOTO (gradient≥90mmHg). Over a median follow up 5.6 years (IQR 2.3–10), 10.5% underwent a myectomy and 23.2% implantable cardiac defibrillator (ICD) implantation for primary (81.8%) or secondary (14.2%) prevention. 42 (6.7%) patients died [SCD 4.9%, heart failure death 0.8%, other 1%] and 21 (3.3%) underwent cardiac transplantation. 69 (10.8%) patients had an arrhythmic event (SCD n=31, resuscitated cardiac arrest n=17, appropriate ICD therapy n=14, sustained VT with haemodynamic compromise n=7). Compared to those presenting after 12 years, those under 12 were less likely to have a family history of SCD (8.9% vs 13%, p:0.047) or report unexplained syncope (6.1% vs 12.3%, p<0.00). The degree of hypertrophy did not differ but a higher proportion of pre-adolescent patients had LVOTO (22.7% vs 14.4%, p<0.00). A higher proportion of pre-adolescent underwent a myectomy (10.5% vs 7.2%, p:0.045) but a lower proportion received a primary prevention ICD (18.9% vs 30.1%, p:0.041). The overall proportion of patients reaching the mortality or arrhythmic end-points did not differ, but SCD and resuscitated cardiac arrest events were more frequent in pre-adolescent patients (4.9% vs 3.9% and 2.7 vs 1.6% respectively).

Conclusion

Pre-adolescent HCM is associated with a high symptom burden and variable cardiac phenotype, comparable to those presenting later in childhood. Despite baseline similarities and equal overall survival, younger patients were less likely to receive a primary prevention ICD despite being more likely to experience a SCD or resuscitated cardiac arrest. This study suggests that younger patients should not be considered a distinct entity for risk stratification and that similar management strategies to older HCM patients should be employed.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): BHF (British Heart Foudnation) MRC (Medical Research Council)

External validation of the HCM Risk-Kids model for predicting sudden cardiac death in childhood hypertrophic cardiomyopathy

Background

Sudden cardiac death (SCD) is the most common mode of death in childhood hypertrophic cardiomyopathy (HCM). The newly developed HCM Risk-Kids model provides clinicians with individualised estimates of risk. The aim of this study was to externally validate the model in a large independent, multi-centre patient cohort.

Methods

A retrospective, longitudinal cohort of patients diagnosed with HCM aged 1–16 years independent of the HCM-Risk-Kids development and internal validation cohort was studied. Data on HCM Risk-Kids predictor variables (unexplained syncope, non-sustained ventricular tachycardia, maximal left ventricular wall-thickness, left atrial diameter and left ventricular outflow tract gradient) were collected from the time of baseline clinical evaluation. The performance of the HCM Risk-Kids model in predicting risk at 5 years was assessed.

Results

The cohort consisted of 421 patients with a median age at baseline evaluation of 12.3 years (IQR 7.3, 14.4). Over a median total follow up 3.48 years (IQR 1.83, 6.62, range 1 month – 20.7 years). Fourteen patients (3.3%) died and 10 (2.4%) underwent cardiac transplantation. Twenty-three patients (5.4%) met the SCD end-point within 5-years, with an overall incidence rate of 2.03 per 100 patient years (95% CI 1.48–2.78). Model validation showed a Harrell's C-index of 0.745 (95% CI 0.52–0.97) and Uno's C-index 0.714 (95% 0.58–0.85) with a calibration slope of 1.15 (95% 0.51–1.80). Figure 1a describes the agreement between predicted and observed 5-year cumulative proportion of SCD or equivalent events for each tertile of predicted risk in one imputed data set. One hundred and twenty-five (29.7%) patients had a predicted 5-year risk of ≥6%. SCD events occurred in 6 patients (2.0%) with a predicted risk <6% and 17 (13.6%) with a predicted risk ≥6. A 5-year predicted risk threshold of ≥6% identified 17 (73.9%) SCD-events with a corresponding C-statistic of 0.702 (95% CI 0.60–0.81) (Figure 1b).

Conclusions

This study reports the first external validation of the HCM Risk-Kids model in a large and geographically diverse patient population. A 5-year predicted risk of ≥6% identified over 70% of events, confirming that HCM Risk-Kids provides a method for individualised risk predictions and shared decision making in children with HCM. Incorporation of the model into routine clinical care will enable independent prospective model validation and assessment of the effect of its use in clinical practice.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): British Heart FoundationMedical Research Council Observed vs predicted risk by tertilesObserved vs predicted by threshold

227A novel risk prediction model for sudden cardiac death in childhood hypertrophic cardiomyopathy (HCM Risk-Kids)

Background

Sudden cardiac death (SCD) is the most common mode of death in childhood hypertrophic cardiomyopathy (HCM) but there is no validated algorithm to identify those at highest risk. This study sought to develop and validate a SCD risk prediction model that provides individualized risk estimates.

Methods

A prognostic model was derived from an international, retrospective, multi-center longitudinal cohort study of 1024 consecutively evaluated patients aged ≤16 years. The model was developed using pre-selected predictor variables [unexplained syncope, maximal left ventricular (LV) wall thickness (MWT), left atrial diameter (LAD), LV outflow tract (LVOT) gradient and non-sustained ventricular tachycardia (NSVT)] identified from the literature and internally validated using bootstrapping.

Results

Over a median follow up of 5.3 years (IQR 2.6, 8.2, total patient years 5984), 89 (8.7%) patients died suddenly or had an equivalent event [annual event rate 1.49 (95% CI 1.15–1.92)]. The pediatric model was developed using pre-selected variables to predict the risk of SCD. The model's ability to predict risk at 5 years was validated; C-statistic was 0.69 (95% CI 0.66–0.72) and the calibration slope was 0.98 (95% CI 0.58–1.38). For every 10 ICDs implanted in patients with ≥6% 5-year SCD risk, potentially 1 patient will be saved from SCD at 5 years.

Conclusions

This new validated risk stratification model for SCD in childhood HCM provides accurate individualized estimates of risk at 5 years using readily obtained clinical risk factors.

Acknowledgement/Funding

British Heart Foundation

P334Prospective FU in various subtypes of cardiomyopathies: insights from the EORP Cardiomyopathy Registry of the ESC

Background

The EORP Cardiomyopathy Registry is a prospective, observational, multinational registry of consecutive patients with cardiomyopathies. The objective of this report is to describe the outcomes at one year of follow-up of adult patients (>18 years old) enrolled in the registry.

Methods

A total of 3,208 patients (median age: 55.0 (43.0; 64.0) years, males: 65.1%) were recruited at baseline. Follow-up data at 1 year were obtained in 2,713 patients (84.6%), including 1,420 with hypertrophic (HCM), 1,105 dilated (DCM), 128 arrhythmogenic right ventricular (ARVC) and 60 restrictive cardiomyopathy (RCM).

Results

Improvement of symptoms (NYHA, chest pain, syncope) was globally observed over time (p<0.001 for each). Additional invasive therapeutics were performed during follow-up: implantation of ICD (primary prevention) (N=109 patients, 5.2%), pacemaker (N=28, 1.2%), heart transplant (N=30, 1,1%), ablation for atrial or ventricular arrhythmia (0.5% & 0.1%). The proportion of patients with history of AF increased from baseline to FU in 3.6% (from 28.2% to 31.8%). ICD therapy at 1 year was delivered more frequently in ARVC then in DCM, HCM and RCM (11.4%, 9.0%; 8.1%, 0% respectively for primary prevention). Major cardiovascular events (MACE) occurred in 29.3% of RCM, 10.5% of DCM, 7.9% of ARVC and 5.3% of HCM. MACE were globally higher in index patients compared to relatives (10.8% vs 4.4%, p<0.001).

When considering geographical areas, MACE were higher in East Europe (13.1%) and lower in South Europe (5.3%) (univariate); heart transplant was higher in West Europe (2.40%) and lower in South Europe (0.25%) (univariate).

Conclusions

Despite symptomatic improvement in most cases, there is still a significant burden of arrhythmic and heart failure events in patients with cardiomyopathies. Outcomes were different not only according to cardiomyopathy subtypes but also in relatives versus index patients.

Acknowledgement/Funding

None

P3443Myotonic dystrophy type 1 in childhood: benign from a cardiac perspective?

Introduction/Purpose

Patients with myotonic dystrophy (DM1) have an increased risk of cardiac conduction disease and ventricular tachycardia associated with sudden cardiac death. Whilst this is well-established in adults, there is little published data on cardiac abnormalities in paediatric patients. To our knowledge this is the largest described cohort of children with DM1. The aim of this study is to better understand the prevalence and type of cardiac abnormalities in paediatric patients with DM1.

Methods

We retrospectively studied consecutive patients referred to our paediatric quaternary institution between 31 December 2000 and 31 January 2019. The electronic patient record was reviewed for the presence of cardiac manifestations, including clinical assessment in clinic, echocardiogram, 12 lead ECG and 24-hour ECG.

Results

60 children were identified with a diagnosis of DM1, 56 (93%) with the congenital form of the disease. The median age at diagnosis was 2.4 (IQR 1.2–24, n=52) months. 51 (85%) were under regular formal cardiac follow up. Cardiac symptoms (syncope, palpitations or chest pain) were present in 6 (10%). 12 lead ECGs were available in 50 (83%) and there was at least one echocardiogram performed in 57 (95%). There were 3 deaths (5%), 2 sudden and unexplained (aged 11 and 6.5 years old). 1 child (2%) underwent pacemaker implantation due to the presence of syncope and evidence of progressive conduction disease (Mobitz II AV block).

During the period of follow-up, 37 (62%) patients had evidence of conduction disease on 12 lead ECG or Holter: 1st degree or higher AV block (35%, n=21), trifascicular block (6.7%, n=4), intraventricular conduction delay (32%, n=19), prolonged QTc (15%, n=9) and junctional rhythm (5% n=3). In addition to abnormalities of conduction, 27 (45%) patients had axis deviation and 12 (20%) abnormal repolarisation.

Abnormalities were present in 8 (14%) of those with an echocardiogram. 2 (3.5%) had hypertrophic cardiomyopathy. Other abnormalities included bicuspid aortic valve, aortic root dilatation, dyskinetic septal motion, pericardial effusion, mitral valve thickening and perimembranous VSD.

24 (40%) patients had a signal averaged ECG of which 14 (58%) were positive in 1 or more vector. 3 (5%) patients had an exercise test with no arrhythmia or progression of conduction abnormalities. 1 patient had an invasive EP study showing a prolonged HV interval but no inducible ventricular tachycardia.

Conclusions

There appears to be a high incidence of cardiac involvement in children with DM1. Adverse events (death and pacemaker implantation) are represented in our cohort. More studies are required in order to establish how we might better identify those at risk of progression of conduction disease and ventricular arrhythmia. Regular and lifelong cardiac follow up is advisable but risk stratification and device implantation remains challenging.

Idiopathic restrictive cardiomyopathy in children is caused by mutations in cardiac sarcomere protein genes

BACKGROUND

Restrictive cardiomyopathy (RCM) is rare in childhood, but has a grave prognosis. The cause of disease in most cases is unknown.

OBJECTIVE

To determine the prevalence of sarcomere protein gene mutations in children with idiopathic RCM.

METHODS

Twelve patients (9 female, mean age 5.1 years) with idiopathic RCM referred between 1991 and August 2006 underwent detailed clinical and genetic evaluation. Nine had received cardiac transplants at the time of the study. The entire coding sequences of the genes encoding eight cardiac sarcomere proteins and desmin were screened for mutations. Familial evaluation was performed on first-degree relatives.

RESULTS

Four patients (33%) had a family history of cardiomyopathy: RCM (n = 2); dilated cardiomyopathy (n = 1) and left ventricular non-compaction (n = 1). Sarcomere protein gene mutations were identified in four patients (33%): 2 in the cardiac troponin I gene (TNNI3) and 1 each in the troponin T (TNNT2) and alpha-cardiac actin (ACTC) genes. Two were de novo mutations and 3 were new mutations. All mutations occurred in functionally important and conserved regions of the genes.

CONCLUSIONS

Sarcomere protein gene mutations are an important cause of idiopathic RCM in childhood. We describe the first mutation in ACTC in familial RCM. The identification of RCM in a child should prompt consideration of sarcomere protein disease as a possible cause and warrants clinical evaluation of the family.

B-type natriuretic peptide predicts disease severity in children with hypertrophic cardiomyopathy

BACKGROUND

In adults with hypertrophic cardiomyopathy (HCM), plasma B-type natriuretic peptide (BNP) levels correlate with dyspnoea class and other markers of disease severity. In children with HCM, symptoms are a poor guide to disease severity and no studies have evaluated the clinical utility of BNP testing.

OBJECTIVE

To assess the relation of BNP levels to symptoms and markers of disease severity in children with HCM.

METHODS

Forty-four consecutive patients with HCM (27 male, age <or=17 years (median 13.6) underwent assessment of plasma BNP. Clinical evaluation of patients was carried out, including ECG, echocardiography and tissue Doppler imaging.

RESULTS

BNP levels correlated with maximal left ventricular (LV) wall thickness (r(s) = 0.631, p<0.001), resting LV outflow tract gradient (r(s) = 0.611, p<0.001), transmitral E/septal Ea (E/Ea(s)) ratio (r(s) = 0.770, p<0.001) and percentage predicted maximum VO(2) (r(s) = -0.390, p = 0.025); there was no relation between BNP and heart failure symptoms. BNP levels were higher in patients who had undergone implantation of an internal cardioverter-defibrillator than in those who had not (309 (interquartile range (IQR) 181-391) vs 50 (IQR 18-188) pg/ml, p = 0.001). BNP was independently associated with E/Ea(s) (r(s) = 0.632, p<0.001) and maximal LV wall thickness (r(s) = 0.412, p = 0.008) on multivariate analysis. At a cut-off point of 50 pg/ml, BNP had a positive predictive value of 93% and a negative predictive value of 80% for predicting E/Ea(s) >10 (area under the receiver operator characteristic curve = 0.875 (p<0.001)).

CONCLUSIONS

BNP levels correlate with non-invasive parameters of disease severity in children with HCM, including measures of raised LV filling pressures. For patients in whom evaluation of symptoms is difficult, BNP may be a useful additional tool in the assessment of disease severity.

Can atrioventricular septal defects exist with intact septal structures?

The hallmark of an atrioventricular septal defect (AVSD) is a common atrioventricular junction, giving rise to a trileaflet left atrioventricular valve. AVSDs have the potential for interatrial shunting alone, interventricular shunting alone, or both. AVSDs without interatrial or interventricular communications have been identified at postmortem examination, but there are no reports of AVSDs with intact septal structures diagnosed in life. Six patients are described with AVSD and intact atrial and ventricular septa diagnosed echocardiographically. This report shows that AVSDs can exist without interatrial or interventricular communications and that the characteristic feature of this condition, the common atrioventricular junction with a trileaflet left atrioventricular valve, can be diagnosed in life by using cross sectional echocardiography. AVSDs with intact septal structures may be more common than previously described.