Johan Saenen

Mutations in a TGF-β Ligand, TGFB3, Cause Syndromic Aortic Aneurysms and Dissections

Background Aneurysms affecting the aorta are a common condition associated with high mortality as a result of aortic dissection or rupture. Investigations of the pathogenic mechanisms involved in syndromic types of thoracic aortic aneurysms, such as Marfan and Loeys-Dietz syndromes, have revealed an important contribution of disturbed transforming growth factor (TGF)-β signaling. Objectives This study sought to discover a novel gene causing syndromic aortic aneurysms in order to unravel the underlying pathogenesis. Methods We combined genome-wide linkage analysis, exome sequencing, and candidate gene Sanger sequencing in a total of 470 index cases with thoracic aortic aneurysms. Extensive cardiological examination, including physical examination, electrocardiography, and transthoracic echocardiography was performed. In adults, imaging of the entire aorta using computed tomography or magnetic resonance imaging was done. Results Here, we report on 43 patients from 11 families with syndromic presentations of aortic aneurysms caused by TGFB3 mutations. We demonstrate that TGFB3 mutations are associated with significant cardiovascular involvement, including thoracic/abdominal aortic aneurysm and dissection, and mitral valve disease. Other systemic features overlap clinically with Loeys-Dietz, Shprintzen-Goldberg, and Marfan syndromes, including cleft palate, bifid uvula, skeletal overgrowth, cervical spine instability and clubfoot deformity. In line with previous observations in aortic wall tissues of patients with mutations in effectors of TGF-β signaling (TGFBR1/2, SMAD3, and TGFB2), we confirm a paradoxical up-regulation of both canonical and noncanonical TGF-β signaling in association with up-regulation of the expression of TGF-β ligands. Conclusions Our findings emphasize the broad clinical variability associated with TGFB3 mutations and highlight the importance of early recognition of the disease because of high cardiovascular risk.

Performant Mutation Identification Using Targeted Next‐Generation Sequencing of 14 Thoracic Aortic Aneurysm Genes

At least 14 causative genes have been identified for both syndromic and nonsyndromic forms of thoracic aortic aneurysm/dissection (TAA), an important cause of death in the industrialized world. Molecular confirmation of the diagnosis is increasingly important for gene‐tailored patient management but consecutive, conventional molecular TAA gene screening is expensive and labor‐intensive. To circumvent these problems, we developed a TAA gene panel for next‐generation sequencing of 14 TAA genes. After validation, we applied the assay to 100 Marfan patients. We identified 90 FBN1 mutations, 44 of which were novel. In addition, Multiplex ligation‐dependent probe amplification identified large deletions in six of the remaining samples, whereas false‐negative results were excluded by Sanger sequencing of FBN1, TGFBR1, and TGFBR2 in the last four samples. Subsequently, we screened 55 syndromic and nonsyndromic TAA patients. We identified causal mutations in 15 patients (27%), one in each of the six following genes: ACTA2, COL3A1, TGFBR1, MYLK, SMAD3, SLC2A10 (homozygous), two in NOTCH1, and seven in FBN1. We conclude that our approach for TAA genetic testing overcomes the intrinsic hurdles of consecutive Sanger sequencing of all candidate genes and provides a powerful tool for the elaboration of clinical phenotypes assigned to different genes.

Life-threatening ventricular arrhythmias during ajmaline challenge in patients with Brugada syndrome: Incidence, clinical features, and prognosis

BACKGROUND Sustained ventricular arrhythmias (sVAs), such as polymorphic ventricular tachycardia or ventricular fibrillation, can complicate ajmaline challenge in patients with Brugada syndrome (BS). OBJECTIVE To assess the incidence of life-threatening sVAs during ajmaline administration in a large series of patients with BS. In addition, clinical characteristics as well as prognosis of these patients were evaluated. METHODS All consecutive patients with ajmaline-induced diagnosis of BS were eligible for this study. RESULTS A total of 503 patients were included. Nine (1.8%) patients (44% men; mean age 26 ± 18 years) developed a life-threatening sVA during ajmaline challenge. Three patients (33%)were children, and 2 (22%) patients experienced sVAs refractory to the first external defibrillation. One patient underwent venoarterial extracorporeal membrane oxygenation to restore sinus rhythm. Age at the time of ajmaline challenge was significantly lower in patients with sVAs compared with patients without sVAs (26 ± 18 years vs 41 ± 18 years; P = .01). Moreover, patients with sVAs presented more frequently with sinus node dysfunction compared with patients with normal response to ajmaline (22.2% vs 1.4%; P = .01). After a mean follow-up time of 29 ± 8 months, none of the patients who had developed a sVA during ajmaline challenge died suddenly or developed further life-threatening ventricular arrhythmias. CONCLUSIONS sVA during ajmaline challenge is not a rare event in BS occurring in 9 (1.8%) patients. Despite its challenging acute treatment, the occurrence of ajmaline-induced sVAs in patients with BS might not identify a category at higher risk for further arrhythmic events.

Monomorphic ventricular tachycardia in patients with Brugada syndrome: A multicenter retrospective study

BACKGROUND Isolated cases of monomorphic ventricular tachycardia (MVT) in patients with Brugada syndrome (BrS) have been reported. OBJECTIVE We aimed to describe the incidence and characteristics of MVT in a cohort of patients with BrS who had received an implantable cardioverter-defibrillator (ICD). METHODS Data from 834 patients with BrS implanted with an ICD in 15 tertiary hospitals between 1993 and 2014 were included. RESULTS The mean age of enrolled patients was 45.3 ± 13.9 years; 200 patients (24%) were women. During a mean follow-up of 69.4 ± 54.3 months, 114 patients (13.7%) experienced at least 1 appropriate ICD intervention, with MVT recorded in 35 patients (4.2%) (sensitive to antitachycardia pacing in 15 [42.8%]). Only QRS width was an independent predictor of MVT in the overall population. Specifically, 6 (17.1%) patients presented with right ventricular outflow tract tachycardia (successfully ablated from the endocardium in 4 and epicardial and endocardial ablation in 1), 2 patients with MVT arising from the left ventricle (1 successfully ablated in the supra lateral mitral annulus), and 2 (5.7%) patients with bundle branch reentry ventricular tachycardia. Significant structural heart disease was ruled out by echocardiography and/or cardiac magnetic resonance imaging. CONCLUSION In this retrospective study, 4.2% of patients with BrS implanted with an ICD presented with MVT confirmed as arising from the right ventricular outflow tract tachycardia in 6, patients with MVT arising from the left ventricle in 2, and patients with bundle branch reentry ventricular tachycardia in 2. Endocardial and/or epicardial ablation was successful in 80% of these cases. These data imply that the occurrence of MVT should not rule out the possibility of BrS. This finding may also be relevant for ICD model selection and programming.

Contact Force in Atrial Fibrillation: Role of Atrial Rhythm and Ventricular Contractions: Co-Force Atrial Fibrillation Study

Background—In an experimental model, variable and intermittent contact force (CF) resulted in a significant decrease in lesion volume. In humans, variability of CF during pulmonary vein isolation has not been characterized. Methods and Results—In 20 consecutive patients undergoing CF-guided circumferential pulmonary vein isolation, 914 radiofrequency applications (530 in sinus rhythm and 384 in atrial fibrillation) were analyzed. The variability of the 60% CF range (CF60%) was 17±9.6 g. Hundred seventy-one (19%) applications were delivered with constant, 717 (78%) with variable, and 26 (3%) with intermittent CF. The mean CF and force-time integral were significantly higher during applications with variable than with intermittent or constant CF. There was no significant difference in CF variability, CF60% variability, and force-time integral between applications delivered in sinus rhythm and atrial fibrillation. The main reasons for CF variability were systolo-diastolic heart movement (29%) and respiration (27%). In 10 additional patients, during adenosine-induced atrioventricular block, the minimum CF significantly increased at 19 sites (5.3±4.4 versus 13.4±5.9 g; P<0.001) and at 16 sites intermittent or variable CF became constant. At only 1 site systolo-diastolic movement remained the main reason for variable CF. Conclusions—CF during pulmonary vein isolation remains highly variable despite efforts to optimize contact. CF and CF parameters were similar during sinus rhythm and atrial fibrillation. The main reasons for CF variability are systolo-diastolic heart movement and respiration. The systolo-diastolic peaks and nadirs of CF are because of ventricular contractions at the large majority of pulmonary vein isolation sites.Background —In an experimental model variable and intermittent contact force (CF) resulted in a significant decrease in lesion volume. In humans, variability of CF during pulmonary vein isolation (PVI) has not been characterized. Methods and Results —In 20 consecutive patients undergoing CF guided circumferential PVI 914 radio-frequency applications (530 in sinus rhythm (SR) and 384 in atrial fibrillation (AF)) were analyzed. The variability of the 60% CF range (CF60%) was 17±9.6 grams. Hundred seventy-one (19%) applications were delivered with constant, 717 (78%) with variable and 26 (3%) with intermittent CF. The mean CF and Force Time Integral (FTI) were significantly higher during applications with variable than with intermittent or constant CF. There was no significant difference in CF variability, CF60% variability and FTI between applications delivered in SR and AF. The main reasons for CF variability were systolo-diastolic heart movement (29%) and respiration (27%). In 10 additional patients, during adenosine induced AV block the minimum CF significantly increased at 19 sites (5.3±4.4 vs. 13.4±5.9 grams, p<0.001) and at 16 sites intermittent or variable CF became constant. At only one site systolo-diastolic movement remained the main reason for variable CF. Conclusions —CF during PVI remains highly variable despite efforts to optimize contact. CF and CF parameters were similar during SR and AF. The main reasons for CF variability are systolo-diastolic heart movement and respiration. The systolo-diastolic peaks and nadirs of CF are due to ventricular contractions at the large majority of PVI sites.

Targeted Next-Generation Sequencing of 51 Genes Involved in Primary Electrical Disease

Primary electrical disease (PED) is characterized by cardiac arrhythmias, which can lead to sudden cardiac death in the absence of detectable structural heart disease. PED encompasses a diversity of inherited syndromes, predominantly Brugada syndrome, early repolarization syndrome, long QT syndrome, short QT syndrome, arrhythmogenic right ventricular cardiomyopathy, and catecholaminergic polymorphic ventricular tachycardia. To overcome the diagnostic challenges imposed by the clinical and genetic heterogeneity of PED, we developed a targeted gene panel for next-generation sequencing of 51 PED genes. The amplified samples were sequenced on MiSeq. To validate the panel, 20 Human Polymorphism Study Center samples and 19 positive control samples were used, with a total of 1479 variants. An analytical sensitivity and specificity of 100% and 99.9% were obtained. After validation, we applied the assay to 114 PED patients. We identified 107 variants in 36 different genes, 18 of which were classified as pathogenic or likely pathogenic, 54 variants were of unknown significance, and 35 were classified as likely benign. We can conclude that the PED Multiplex Amplification of Specific Targets for Resequencing Plus assay is a proficient and highly reliable test to routinely screen patients experiencing primary arrhythmias.

Prospective study of tricuspid valve regurgitation associated with permanent leads in patients undergoing cardiac rhythm device implantation: Background, rationale, and design

Given the increasing numbers of cardiac device implantations worldwide, it is important to determine whether permanent endocardial leads across the tricuspid valve can promote tricuspid regurgitation (TR). Virtually all current data is retrospective, and indicates a signal of TR being increased after permanent lead implantation. However, the precise incidence of moderate or greater TR post-procedure, the exact mechanisms (mechanical, traumatic, functional), and the hemodynamic burden and clinical effects of this putative increase in TR, remain uncertain. We have therefore designed a multicenter, international, prospective study of 300 consecutive patients (recruitment completed, baseline data presented) who will undergo echocardiography and clinical assessment prior to, and at 1-year post device insertion. This prospective study will help determine whether cardiac device-associated TR is real, what are its potential mechanisms, and whether it has an important clinical impact on cardiac device patients.

Genetics of sudden cardiac death in the young

Sudden cardiac death (SCD) has an enormous impact on those who are left behind, evoking strong feelings of anxiety and incomprehension because such a dramatic event was not anticipated. Moreover, over the last decade a prominent genetic contribution to the pathogenesis of SCD has been unveiled. As many inherited cardiac diseases show an autosomal dominant pattern of inheritance, the risk of carrying the same inherited predisposition is a real concern for the relatives. In this article, we discuss the major causes of primary electrical disorders, cardiomyopathies and thoracic aortic dissection and address issues in genotype–phenotype correlation, personalized management and cardiogenetic counselling.

Contact Force Variability during Catheter Ablation of Atrial Fibrillation: The Role of Atrial Rhythm and Ventricular Contractions: Co-Force AF Study

Background—In an experimental model, variable and intermittent contact force (CF) resulted in a significant decrease in lesion volume. In humans, variability of CF during pulmonary vein isolation has not been characterized. Methods and Results—In 20 consecutive patients undergoing CF-guided circumferential pulmonary vein isolation, 914 radiofrequency applications (530 in sinus rhythm and 384 in atrial fibrillation) were analyzed. The variability of the 60% CF range (CF60%) was 17±9.6 g. Hundred seventy-one (19%) applications were delivered with constant, 717 (78%) with variable, and 26 (3%) with intermittent CF. The mean CF and force-time integral were significantly higher during applications with variable than with intermittent or constant CF. There was no significant difference in CF variability, CF60% variability, and force-time integral between applications delivered in sinus rhythm and atrial fibrillation. The main reasons for CF variability were systolo-diastolic heart movement (29%) and respiration (27%). In 10 additional patients, during adenosine-induced atrioventricular block, the minimum CF significantly increased at 19 sites (5.3±4.4 versus 13.4±5.9 g; P<0.001) and at 16 sites intermittent or variable CF became constant. At only 1 site systolo-diastolic movement remained the main reason for variable CF. Conclusions—CF during pulmonary vein isolation remains highly variable despite efforts to optimize contact. CF and CF parameters were similar during sinus rhythm and atrial fibrillation. The main reasons for CF variability are systolo-diastolic heart movement and respiration. The systolo-diastolic peaks and nadirs of CF are because of ventricular contractions at the large majority of pulmonary vein isolation sites.Background —In an experimental model variable and intermittent contact force (CF) resulted in a significant decrease in lesion volume. In humans, variability of CF during pulmonary vein isolation (PVI) has not been characterized. Methods and Results —In 20 consecutive patients undergoing CF guided circumferential PVI 914 radio-frequency applications (530 in sinus rhythm (SR) and 384 in atrial fibrillation (AF)) were analyzed. The variability of the 60% CF range (CF60%) was 17±9.6 grams. Hundred seventy-one (19%) applications were delivered with constant, 717 (78%) with variable and 26 (3%) with intermittent CF. The mean CF and Force Time Integral (FTI) were significantly higher during applications with variable than with intermittent or constant CF. There was no significant difference in CF variability, CF60% variability and FTI between applications delivered in SR and AF. The main reasons for CF variability were systolo-diastolic heart movement (29%) and respiration (27%). In 10 additional patients, during adenosine induced AV block the minimum CF significantly increased at 19 sites (5.3±4.4 vs. 13.4±5.9 grams, p<0.001) and at 16 sites intermittent or variable CF became constant. At only one site systolo-diastolic movement remained the main reason for variable CF. Conclusions —CF during PVI remains highly variable despite efforts to optimize contact. CF and CF parameters were similar during SR and AF. The main reasons for CF variability are systolo-diastolic heart movement and respiration. The systolo-diastolic peaks and nadirs of CF are due to ventricular contractions at the large majority of PVI sites.

Left ventricular non-compaction with Ebstein anomaly attributed to a TPM1 mutation

Left ventricular non-compaction (cardiomyopathy) (LVN(C)) is a rare hereditary cardiac condition, resulting from abnormal embryonic myocardial development. While it mostly occurs as an isolated condition, association with other cardiovascular manifestations such as Ebstein anomaly (EA) has been reported. This congenital heart defect is characterized by downward displacement of the tricuspid valve and leads to diminished ventricular size and function. In an autosomal dominant LVN(C) family consisting of five affected individuals, of which two also presented with EA and three with mitral valve insufficiency, we pursued the genetic disease cause using whole exome sequencing (WES). WES revealed a missense variant (p.Leu113Val) in TPM1 segregating with the LVN(C) phenotype. TPM1 encodes α-tropomyosin, which is involved in myocardial contraction, as well as in stabilization of non-muscle cytoskeletal actin filaments. So far, LVN(C)-EA has predominantly been linked to pathogenic variants in MYH7. However, one sporadic LVN(C)-EA case with a de novo TPM1 variant has recently been described. We here report the first LVN(C)-EA family segregating a pathogenic TPM1 variant, further establishing the association between EA predisposition and TPM1-related LVN(C). Consequently, we recommend genetic testing for both MYH7 and TPM1 in patients or families in which LVN(C)/non-compaction and EA coincide.