Implantable loop recorders in patients with a structural or electrical heart disease: comparison of the clinical value in patients with and without a history of syncope

Funding Acknowledgements Type of funding sources: None. Background Patients with structural and electrical heart disease are at increased risk for sudden cardiac death. Guidelines recommend the use of an implantable loop recorder (ILR) in symptomatic patients when symptoms are sporadic and suspected to be related to arrhythmias. In clinical practice, an ILR is mainly used in patients with unexplained syncope. Purpose To compare the clinical value of an ILR in patients with a heart disease and a history of syncope versus those with non-syncopal suspected arrhythmia-related symptoms. Methods In this observational single-center study we included symptomatic patients with structural or electrical heart disease who received an ILR. The primary endpoint was an actionable event which was defined as an arrhythmic event leading to a change in clinical management. The secondary endpoint was an event leading to implantation of a pacemaker or implantable cardioverter-defibrillator (ICD). Results A total of 120 patients (mean age 47 ± 17 years, 49% men) were included. Underlying disease substrate was inherited cardiomyopathy (31%), congenital heart disease (28%), channelopathy (23%), and other structural heart disease (18%).There were 43 patients with a history of syncope (group A) and 77 patients with non-syncopal symptoms (group B) such as palpitations, dizziness and/or near-syncope at baseline. During a median follow-up of 19 months (IQR 8-36), a primary endpoint was reached in 14 patients (33%) of group A, and in 28 patients (36%) of group B (logrank P = 0.54, Figure A). There was also no significant difference in the cumulative rate of cardiac device implantation between group A and B, 14% versus 10%, respectively (logrank P = 0.97, Figure B). Conclusion Our results show no differences in ILR yield in patients with structural or electrical heart disease who present with any suspected arrhythmia-related symptom, including those with non-syncopal symptoms. Abstract Figure.

Brugada-like electrocardiogram pattern in a young man taking a proton-pump inhibitor

The Brugada syndrome (BrS) is an electrical heart disease with complex inheritance (some cases with SCN5A mutations), characterized by specific electrocardiogram (ECG) markers and high risk of associated lethal ventricular arrhythmias [1]. The ECG signature of BrS consists of right precordial ST-segment elevation (≥2 mm) followed by negative T waves [1]. It sometimes includes the findings of right bundle branch block (RBBB). In certain cases, the typical ECG pattern is present intermittently which creates a potential problem for reaching the diagnosis of BrS. Another problem in diagnosing BrS is the presence of so-called Brugada phenocopies (BrPs), i.e. an acquired Brugada-like ECG pattern that are visually identical and indistinguishable from true BrS [2]. This ECG pattern can be caused by other conditions including ischemia of the ventricular septum and/or right ventricle or by taking certain medications [2]. Proton-pump inhibitors (PPIs) are widely prescribed, often for prolonged use, and have been associated with electrolyte disturbances and cardiac arrhythmias [3,4]. We hereby present for the first time the case of a patient with an ECG suggestive of BrS while taking PPI; but no other medication known to cause BrS. The BrS ECG pattern disappeared a few months after stopping the medication.

Role of Non-Coding Variants in Brugada Syndrome

Brugada syndrome (BrS) is an inherited electrical heart disease associated with a high risk of sudden cardiac death (SCD). The genetic characterization of BrS has always been challenging. Although several cardiac ion channel genes have been associated with BrS, SCN5A is the only gene that presents definitive evidence for causality to be used for clinical diagnosis of BrS. However, more than 65% of diagnosed cases cannot be explained by variants in SCN5A or other genes. Therefore, in an important number of BrS cases, the underlying mechanisms are still elusive. Common variants, mostly located in non-coding regions, have emerged as potential modulators of the disease by affecting different regulatory mechanisms, including transcription factors (TFs), three-dimensional organization of the genome, or non-coding RNAs (ncRNAs). These common variants have been hypothesized to modulate the interindividual susceptibility of the disease, which could explain incomplete penetrance of BrS observed within families. Altogether, the study of both common and rare variants in parallel is becoming increasingly important to better understand the genetic basis underlying BrS. In this review, we aim to describe the challenges of studying non-coding variants associated with disease, re-examine the studies that have linked non-coding variants with BrS, and provide further evidence for the relevance of regulatory elements in understanding this cardiac disorder.

P988Implantable cardioverter defibrillators in patients with electrical heart disease and hypertrophic cardiomyopathy - data from the German device Registry

Background Implantable cardioverter- defibrillator (ICD) therapy is established for prevention of sudden cardiac death (SCD) in different entities. However, data from large patient cohorts on patients with electrical heart disease of hypertrophic cardiomyopathy (HCM) is rare. Therefore, we investigated these patients by analysing registry data from a multi-center “real-life” registry. Methods The German Device Registry (DEVICE) is a nationwide, prospective registry with one-year follow-up investigating 5450 patients receiving device implantations in 50 German centres. The present analysis of DEVICE focussed on patients with electrical heart disease or HCM who received an ICD for primary or secondary prevention. Results 174 patients with HCM and 112 patients with electrical heart disease were compared with 5164 other ICD patients. Median follow-up was 17.0 months. Patients in the control group were significantly older. Of note, overall mortality after one year was 1.8% in HCM patients, 6.6% in patients with electrical heart disease and 7.3% in the control group. Patients in the control group presented significantly more severe comorbidities. In contrast to HCM patients and the control group where primary prevention was the major indication for ICD implantation 77.5% of patients with electrical heart disease received an ICD for secondary prevention. The number of surgical revisions was higher in patients with electrical heart disease. Conclusion Data from the present registry display a surprisingly high mortality in patients with electrical heart disease equivalent to the control group. A high proportion of patients who received an ICD for secondary prevention may be regarded as a major determinant for these results while severe comorbidities such as diabetes, hypertension and renal failure are major determinants for mortality in the control cohort.

Monomorphic Ventricular Arrhythmias in Athletes

Ventricular arrhythmias are challenging to manage in athletes with concern for an elevated risk of sudden cardiac death (SCD) during sports competition. Monomorphic ventricular arrhythmias (MMVA), while often benign in athletes with a structurally normal heart, are also associated with a unique subset of idiopathic and malignant substrates that must be clearly defined. A comprehensive evaluation for structural and/or electrical heart disease is required in order to exclude cardiac conditions that increase risk of SCD with exercise, such as hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy. Unique issues for physicians who manage this population include navigating athletes through the decision of whether they can safely continue their chosen sport. In the absence of structural heart disease, therapies such as radiofrequency catheter ablation are very effective for certain arrhythmias and may allow for return to competitive sports participation. In this comprehensive review, we summarise the recommendations for evaluating and managing athletes with MMVA.

A NovelSCN5AMutation in a Patient with Coexistence of Brugada Syndrome Traits and Ischaemic Heart Disease

Brugada syndrome (BrS) is a primary electrical heart disease, which can lead to sudden cardiac death. In older patients with BrS, the disease may coexist with ischaemic heart disease (IHD) and recent studies support a synergistic proarrhythmic effect of the two disease entities. We report a case that illustrates this. The index patient was a middle-aged patient with BrS traits, IHD, and aborted sudden cardiac death. Mutation analysis discovered a novel mutation P468L in theNaV1.5 sodium channel. Surprisingly, voltage-clamp experiments on the wild-type and mutantNaV1.5 channels expressed in HEK cells revealed no functional effect of the mutation. In a patient like ours, the distinction between IHD and BrS as the cause of an aborted sudden cardiac death is hard to establish and mounting evidence shows that coexistence of the two may have a synergistic proarrhythmic effect.