Mitral Annular Disjunction in Idiopathic Ventricular Fibrillation Patients: Just a Bystander or a Potential Cause?

AIMS

Previously, we demonstrated that inferolateral mitral annular disjunction (MAD) is more prevalent in patients with idiopathic ventricular fibrillation (IVF) than in healthy controls. In the present study, we advanced the insights into the prevalence and ventricular arrhythmogenicity by inferolateral MAD in an even larger IVF cohort.

METHODS AND RESULTS

This retrospective multicentre study included 185 IVF patients (median age 39 [27, 52] years, 40% female). Cardiac magnetic resonance images were analysed for mitral valve and annular abnormalities and late gadolinium enhancement. Clinical characteristics were compared between patients with and without MAD. MAD in any of the 4 locations was present in 112 (61%) IVF patients and inferolateral MAD was identified in 24 (13%) IVF patients. Mitral valve prolapse (MVP) was found in 13 (7%) IVF patients. MVP was more prevalent in patients with inferolateral MAD compared with patients without inferolateral MAD(42% vs. 2%, p < 0.001). Proarrhythmic characteristics in terms of a high burden of premature ventricular complexes (PVC) and non-sustained ventricular tachycardia (VT) were more prevalent in patients with inferolateral MAD compared to patients without inferolateral MAD (67% vs. 23%, p < 0.001 and 63% vs 41%, p = 0.046, respectively). Appropriate implantable cardioverter defibrillator therapy during follow-up was comparable for IVF patients with or without inferolateral MAD (13% vs. 18%, p = 0.579).

CONCLUSION

A high prevalence of inferolateral MAD and MVP is a consistent finding in this large IVF cohort. The presence of inferolateral MAD is associated with a higher PVC burden and non-sustained VTs. Further research is needed to explain this potential interplay.

Accuracy of mobile 6-lead electrocardiogram device for assessment of QT interval: a prospective validation study

INTRODUCTION

Ambulatory assessment of the heart rate-corrected QT interval (QTc) can be of diagnostic value, for example in patients on QTc-prolonging medication. Repeating sequential 12-lead electrocardiograms (ECGs) to monitor the QTc is cumbersome, but mobile ECG (mECG) devices can potentially solve this problem. As the accuracy of single-lead mECG devices is reportedly variable, a multilead mECG device may be more accurate.

METHODS

This prospective dual-centre study included outpatients visiting our cardiology clinics for any indication. Participants underwent an mECG recording using a smartphone-enabled 6‑lead mECG device immediately before or immediately after a conventional 12-lead ECG recording. Multiple QTc values in both recordings were manually measured in leads I and II using the tangent method and subsequently compared.

RESULTS

In total, 234 subjects were included (mean ± standard deviation (SD) age: 57 ± 17 years; 58% males), of whom 133 (57%) had cardiac disease. QTc measurement in any lead was impossible due to artefacts in 16 mECGs (7%) and no 12-lead ECGs. Mean (± SD) QTc in lead II on the mECG and 12-lead ECG was 401 ± 30 and 406 ± 31 ms, respectively. Mean (± SD) absolute difference in QTc values between both modalities was 12 ± 9 ms (r = 0.856; p < 0.001). In 55% of the subjects, the absolute difference between QTc values was < 10 ms.

CONCLUSION

A 6-lead mECG allows for QTc assessment with good accuracy and can be used safely in ambulatory QTc monitoring. This may improve patient satisfaction and reduce healthcare costs.

Pharmacological treatment of short-coupled idiopathic ventricular fibrillation: A review

Short-coupled idiopathic ventricular fibrillation (IVF) is a subtype of IVF in which episodes of polymorphic ventricular tachycardia or ventricular fibrillation are initiated by short-coupled premature ventricular contractions (PVCs). Our understanding of the pathophysiology is evolving, with evidence suggesting that these malignant PVCs originate from the Purkinje system. In most cases, the genetic underpinning has not been identified. Whereas the implantation of an implantable cardioverter-defibrillator is uncontroversial, the choice of pharmacological treatment is the subject of discussion. In this review, we summarize the available knowledge on pharmacological therapy in short-coupled IVF and provide our recommendations for management of patients with this syndrome.

Automated analysis of finger blood pressure recordings provides insight in determinants of baroreflex sensitivity and heart rate variability-the HELIUS study

Sympathovagal balance is important in the pathogenesis of hypertension and independently associated with mortality. We evaluated the value of automated analysis of cross-correlation baroreflex sensitivity (xBRS) and heart rate variability (HRV) and its relationship with clinical covariates in 13,326 participants from the multi-ethnic HELIUS study. Finger blood pressure (BP) was continuously recorded, from which xBRS, standard deviation of normal-to-normal intervals (SDNN), and squared root of mean squared successive difference between normal-to-normal intervals (RMSDD) were determined. A subset of 3356 recordings > 300 s was used to derive the minimally required duration by comparing shortened to complete recordings, defined as intraclass correlation (ICC) > 0.90. For xBRS and SDNN, 120 s and 180 s were required (ICC 0.93); for RMSDD, 60 s (ICC 0.94) was sufficient. We included 10,252 participants (median age 46 years, 54% women) with a recording > 180 s for the regression. xBRS, SDNN, and RMSDD decreased linearly up to 50 years of age. For xBRS, there was a signification interaction with sex, with for every 10 years a decrease of 4.3 ms/mmHg (95%CI 4.0-4.6) for men and 5.9 ms/mmHg (95%CI 5.6-6.1) for women. Using splines, we observed sex-dependent nonlinearities in the relation with BP, waist-to-hip-ratio, and body mass index. Future studies can help unravel the dynamics of these relations and assess their predictive value. Panel 1 depicts automatic analysis and filtering of finger BP recordings, panel 2 depicts computation of xBRS from interpolated beat to beat data of systolic BP and interbeat interval, and (IBI) SDNN and RMSDD are computed directly from the filtered IBI dataset. Panel 3 depicts the results of large-scale analysis and relation of xBRS with age, sex, blood pressure and body mass index.

Cardiac radioablation does not worsen cardiac function: preliminary safety results of the prospective STARNL-1 trial

Background

Cardiac radioablation for ventricular tachycardia (VT) appears to be highly effective and safe in patients with recurrent VT despite anti-arrhythmic therapy and catheter ablation(s), although global experience is currently very limited. Detailed echocardiographic strain analysis could provide important insights in (subclinical) functional safety. Importantly, current stereotactic cardiac radioablation techniques includes irradiation of the VT substrate but, inherently, also includes irradiation of the VT border zone and some healthy cardiac tissue. The latter particularly may result in detoriation of cardiac function after cardiac radioablation.

Purpose

To evaluate functional echocardiographic safety of cardiac radioablation.

Methods

The STARNL-1 trial is a prospective, monocenter, single-arm, pre-post intervention study. Six patients with recurrent VT despite high dose anti-arrhythmic drugs, after (single or multiple) conventional catheter ablation and deemed unsuited for repeat catheter ablation, were treated with a single fraction 25 Gy radiotherapy dose. Per protocol, patients underwent echocardiograms at baseline, 24 hours after treatment, and 3 months after treatment. Echocardiograms were analysed using 2D-speckle tracking. Mean radiotherapy dose per segment was calculated according to the AHA 17-segment model. Echocardiographic parameters were compared between baseline, 24 hours and 3 months, and correlated to radiotherapy dose.

Results

Patients were all male (age 55–83 years), all suffered from ischaemic cardiomyopathy, and all completed 3 month follow-up. At baseline, median left ventricle ejection fraction (LVEF) was 38% [30; 47] and median global longitudinal strain (GLS) −8% [−12; −5]. Interestingly, LVEF significantly improved 24 hours after treatment (42% [36; 49], p=0.046) but GLS did not change (−7% [−12; −5], p=0.833). At 3 months, both LVEF and GLS were unchanged compared to baseline (LVEF 39% [33; 49%], p=0.463; GLS −6% [−12; −5], p=0.893). The difference in longitudinal strain per segment before and after treatment did not correlate with the mean radiotherapy dose per segment, both 24 hours after treatment (Pearson coefficient −0.082, p=0.410) and 3 months after treatment (Pearson coefficient −0.005, p=0.957). In Figure 1 an illustrative case is presented.

Conclusion(s)

Cardiac radioablation for VT does not worsen (subclinical) cardiac function within the first 3 months after treatment.

Funding Acknowledgement

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

Standardizing the cardiac radioablation targeting workflow: enabling semi-automated angulation and segmentation of the heart according to the American Heart Association segmented model

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Dutch Heart Foundation

Purpose

Cardiac radioablation has evolved as a potential treatment modality for therapy-refractory ventricular tachycardia. To standardize cardiac radioablation treatments, promote accurate communication and target identification, and to assess toxicity, robust and reproducible methods for angulation and cardiac segmentation are paramount. In this study, we developed and evaluated a workflow for semi-automated angulation and segmentation according to the American Heart Association (AHA) 17-segment model.

Methods and materials

The workflow for semi-automated angulation and segmentation of the planning-CT was based on an in-house developed tool requiring placement of only 4 point-markers and a rotation matrix. For angulation, 2 markers defining the cardiac long-axis were placed: at the cardiac apex and at the center of the mitral valve (figure A). A rotation matrix was derived that angulates the CT-volume, resulting in the cardiac short axis (figure B). Segmentation was subsequently performed based on marking the two left ventricular hinge points (figure BC). To evaluate reproducibility, 5 observers independently placed markers in planning-CTs of 6 patients.

Results

The Root-Mean-Square of the standard deviation for the angulation and segmentation marker positions were all below 0.52cm. The 17-segments were subsequently generated and compared between the observers resulting in a median dice coefficient of 0.8 [0.70;0.87] and a median of the mean Hausdorff distance of 0.09cm [0.05;0.17]. Figure D shows the heat maps of two illustrative segments indicating the percentage agreement per voxel between the 5 observers. The interquartile ranges of Euler angles α and β, determined by the angulation markers, was less than 30 for all patients except one. For the γ angle, determined by the hinge point markers, the interquartile range was up to 120.

Conclusion

In this study, a workflow for cardiac radioablation is presented that enables reproducible semi-automatic cardiac angulation and segmentation of the planning-CT according to the AHA 17-segment model. This workflow can be easily implemented and be used to promote communication between radiation oncology and cardiology, enables cardiology-oriented targeting and permits focused toxicity evaluations.

Prevalence of mitral annulus disjunction and mitral valve prolapse in a multicenter cohort of idiopathic ventricular fibrillation patients

Funding Acknowledgements

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

Background

Idiopathic ventricular fibrillation (IVF) is diagnosed in patients with sudden onset of ventricular fibrillation of which the origin is not identified after extensive evaluations. Recent studies suggest an association between mitral annulus disjunction (MAD), mitral valve prolapse (MVP) and ventricular arrhythmias[1,2]. The prevalence of MAD and MVP in IVF patients in this regard, is not well established.

Purpose

To explore prevalence of MAD and MVP in IVF patients.

Methods

In this retrospective multicenter cohort study, Cardiac Magnetic Resonance images from IVF patients (i.e., negative for ischemia, cardiomyopathy and channelopathies) and matched control subjects were analyzed for MAD (≥2mm) and MVP (&gt;2mm).

Results

In total, 71 IVF patients (mean age 39, 59% male) and 71 controls (mean age 41, 58% male) were included. MAD in the inferolateral wall was more prevalent in IVF patients versus healthy controls (6 [10%] vs. 1 [1%], p = 0.035). MVP was only seen in IVF patients and not in controls (4 [7%] vs. 0 [0%], p = 0.037). MVP was observed both in IVF patients with (n = 3) and without (n = 1) MAD. Patients with MAD did not show papillary muscle fibrosis. Four (67%) patients with MAD showed frequent ventricular ectopy from the basal myocardial region.

Conclusion

Inferolateral MAD and MVP were significantly more prevalent in IVF patients compared to healthy controls (figure). This is in line with previous studies suggesting a correlation between mitral valve disease and IVF. Our findings support further exploration of the pathophysiological mechanisms underlying a subset of IVF that associates with MAD and MVP.

Patients with a DPP6 risk- haplotype for familial idiopathic ventricular fibrillation have normal left systolic function but abnormal deformation

Funding Acknowledgements

Type of funding sources: None.

Introduction

An aberrant DPP6 mutation haplotype on chromosome 7 is associated with familial idiopathic ventricular fibrillation in severely affected Dutch families with numerous cases of  sudden cardiac death (SCD) So far, no clinical parameters could be linked to predict SCD risk other than this genetic predisposition. In various other cardiac disease, global longitudinal strain (GLS) and mechanical dispersion (MD), both markers of left ventricular (LV) dysfunction, are predictive tools for patients at risk for ventricular arrhythmias (VA) and SCD. The goal of the current study was to investigate whether LV dysfunction, detected by GLS and MD, is present in patients with DPP6 haplotype.

Method

DPP6 risk-haplotype carriers with sufficient echocardiographic images were included as cases (n = 31, 15 males mean age 41 ± 11 years) and individuals evaluated during cascade screening who were tested but appeared not to be affected as controls (n = 14, 7 males, mean  age 39 ± 12 years). Echocardiographic bi-plane ejection fraction (LVEF), GLS and MD of the left ventricular were determined.

Results

LVEF was similar between DPP6 cases (57.3%) and controls (60.5%, p = 0.07). In contrast, the GLS of the LV (-18.0%) of DPP6 cases was significant lower compared to controls (-21.1%, p &lt; 0.0001). MD in DPP6 cases (43.4ms) was significantly higher than in controls (26.7ms, p &lt; 0.0001).

Conclusion

DPP6 risk- haplotype carriers have similar LVEF, but significant lower LV-GLS and higher mechanical dispersion than controls. These findings can be used for clinical discrimination. Whether these markers can be used for prediction of clinical events has to be determined after a longer follow up.

echocardiographic characteristics controls DPP6 p-value LVEF (%) 60.5 57.3 0.07 GLS LV (%) -21.2 -18.0 0.0001 MD ( ms) 26.7 43.4 0.0001

Catheter ablation in highly symptomatic Brugada patients: a Dutch case series

AIMS

In the past few years, promising results were described in targeting the arrhythmogenic substrate of the epicardial right ventricular outflow tract (RVOT) region in patients with Brugada syndrome (BrS). In this report, we describe our experience with endo- and epicardial substrate mapping and ablation in a series of highly symptomatic BrS patients.

METHODS

This case series consists of seven patients with clinical BrS diagnosis who underwent catheter ablation in two Dutch hospitals (Isala hospital Zwolle; and Amsterdam University Medical Centre, location AMC, Amsterdam) and Hamad Heart Hospital in Qatar between 2013 and 2017. All patients had an ICD and recurrent ventricular arrhythmia (VA) episodes. All patients underwent endo-and epicardial mapping of the RVOT region. Elimination of all abnormal potentials and disappearance of BrS ECG pattern during the ablation procedure was the aimed endpoint.

RESULTS

The study group consisted of seven patients with mean age 45.6 ± 16.9 years. Five patients had SCN5A mutations. One patient was excluded from analysis, since ablation could not be performed due to a very large low-voltage area and was later diagnosed with arrhythmogenic right ventricular cardiomyopathy, associated with an SCN5A mutation. One patient underwent both endo- and epicardial ablation to eliminate VA. During a mean follow-up of 3.6 ± 1.5 years, 5/6 patients remained VA free with two patients continuing quinidine.

CONCLUSION

In patients with BrS and drug-refractory VA, ablation of the arrhythmogenic substrate in the RVOT region was associated with excellent long-term VA-free survival. The majority of these highly symptomatic BrS patients had an SCN5A mutation and also low-voltage areas epicardially.

The brisk-standing-test for long QT syndrome in prepubertal school children: defining normal

Aims

Long QT syndrome (LQTS) is associated with malignant arrhythmias and sudden death from birth to advanced age. Prolongation of the QT-interval, may however be concealed on standard electrocardiograms (ECG). The brisk-standing-test (BST) was developed to guide LQTS-diagnosis and treatment in adults. We hypothesized that the BST may be used in prepubertal children to identify LQTS subjects. Accordingly, reference values for the BST should be available to prevent incorrect diagnosis and treatment of LQTS. In this study, we aim to present reference values for prepubertal children.

Methods and results

Healthy, prepubertal children, aged 7-13 years underwent a standard supine resting ECG and during continuous ECG recording performed a BST. The QT-interval and heart rate corrected QTc were measured during the different BST stages. Fifty-seven children, 29 boys (10.2 ± 1.1 years) and 28 girls (9.9 ± 1.1 years) were included. Baseline characteristics and response to standing were not statistically different for boys and girls: mean supine pre-standing heart rate 74 ± 9 vs. 77 ± 9 bpm, supine pre-standing QTc 406 ± 27 vs. 407 ± 17 ms, maximal heart rate upon standing 109 ± 11 vs. 112 ± 11 bpm, and QTc at maximal heart rate 484 ± 29 vs. 487 ± 35 ms. The QT interval corrected for heart rate-prolongation at maximal tachycardia after standing was 79 ± 26 (19-144) ms, which is significantly longer than previously published values in adults (50± 30 ms).

Conclusions

The QT interval corrected for heart rate prolongation after brisk standing in healthy prepubertal children is more pronounced than in healthy adults. This finding advocates distinct prepubertal cut-off values because using adult values for prepubertal children would yield false positive results with the risk of incorrect LQTS-diagnosis and overtreatment.

Takotsubo cardiomyopathy shortly following pacemaker implantation-case report and review of the literature

We describe a patient with acute heart failure shortly after pacemaker implantation. With the documentation of typical dyskinesia of the apical segments with hyperdynamic contractility of the basal segments and a normal coronary angiogram, pacemaker implantation-induced Takotsubo cardiomyopathy was diagnosed. Supportive care was administered and within several days the patient's symptoms resolved. After several weeks, the left ventricular function had fully recovered. A review of the literature on Takotsubo cardiomyopathy after pacemaker implantation is presented.

Founder mutations in the Netherlands: familial idiopathic ventricular fibrillation and DPP6

In this part of a series on founder mutations in the Netherlands, we review familial idiopathic ventricular fibrillation linked to the DPP6 gene. Familial idiopathic ventricular fibrillation determines an intriguing subset of the inheritable arrhythmia syndromes as there is no recognisable phenotype during cardiological investigation other than ventricular arrhythmias highly associated with sudden cardiac death. Until recently, it was impossible to identify presymptomatic family members at risk for fatal events. We uncovered several genealogically linked families affected by numerous sudden cardiac deaths over the past centuries, attributed to familial idiopathic ventricular fibrillation. Notably, ventricular fibrillation in these families was provoked by very short coupled monomorphic extrasystoles. We were able to associate their phenotype of lethal arrhythmic events with a haplotype harbouring the DPP6 gene. While this gene has not earlier been related to cardiac arrhythmias, we are now able, for the first time, to identify and to offer timely treatment to presymptomatic family members at risk for future fatal events solely by genetic analysis. Therefore, when there is a familial history of unexplained sudden cardiac deaths, a link to the DPP6 gene may be explored as it may enable risk evaluation of the remaining family members. In addition, when closely coupled extrasystoles initiate ventricular fibrillation in the absence of other identifiable causes, a link to the DPP6 gene should be suspected.

Founder mutations in hypertrophic cardiomyopathy patients in the Netherlands

In this part of a series on cardiogenetic founder mutations in the Netherlands, we review the Dutch founder mutations in hypertrophic cardiomyopathy (HCM) patients. HCM is a common autosomal dominant genetic disease affecting at least one in 500 persons in the general population. Worldwide, most mutations in HCM patients are identified in genes encoding sarcomeric proteins, mainly in the myosin-binding protein C gene (MYBPC3, OMIM #600958) and the beta myosin heavy chain gene (MYH7, OMIM #160760). In the Netherlands, the great majority of mutations occur in the MYBPC3, involving mainly three Dutch founder mutations in the MYBPC3 gene, the c.2373_2374insG, the c.2864_2865delCT and the c.2827C>T mutation. In this review, we describe the genetics of HCM, the genotype-phenotype relation of Dutch founder MYBPC3 gene mutations, the prevalence and the geographic distribution of the Dutch founder mutations, and the consequences for genetic counselling and testing. (Neth Heart J 2010;18:248-54.).

Pneumococcal aortitis: an insidious diagnosis

A patient with Streptococcus pneumoniae aortitis is presented. Because of nonspecific symptoms (fever and back pain) there was a long diagnostic delay. In addition, the aortitis was located near the renal arteries which severely hampered early surgical treatment. Although emergency surgery was performed when aortic rupture occurred, the patient did not survive. Infectious arteritis of large vessels is a diagnosis often made late and associated with high mortality.

Recurrent and Founder Mutations in the Netherlands: the Long-QT Syndrome

Background and objective

The long-QT syndrome (LQTS) is associated with premature sudden cardiac deaths affecting whole families and is caused by mutations in genes encoding for cardiac proteins. When the same mutation is found in different families (recurrent mutations), this may imply either a common ancestor (founder) or multiple de novo mutations. We aimed to review recurrent mutations in patients with LQTS.

Methods

By use of our databases, we investigated the number of mutations that were found recurrently (at least three times) in LQT type 1–3 patients in the Netherlands. We studied familial links in the apparently unrelated probands, and we visualised the geographical distribution of these probands. Our results were compared with published literature of founder effects in LQTS outside the Netherlands.

Results

We counted 14 recurrent LQT mutations in the Netherlands. There are 326 identified carriers of one of these mutations. For three of these mutations, familial links were found between apparently unrelated probands.

Conclusion

Whereas true LQT founder mutations are described elsewhere in the world, we cannot yet demonstrate a real founder effect of these recurrent mutations in the Netherlands. Further studies on the prevalence of these mutations are indicated, and haplotype-sharing of the mutation carriers is pertinent to provide more evidence for founder mutation-based LQTS pathology in our country.

[Genetic identification of patients and families with a long-QT syndrome: large regional differences in the result of 10 years]

OBJECTIVE

To determine the pattern of referral of Dutch patients with a long-QT syndrome (LQTS) on the basis of the postal codes of the LQTS probands from whom blood samples were submitted for DNA diagnostics.

DESIGN

. Retrospective cohort study.

METHOD

From the databases that are coupled to DNA diagnostics, all index patients were included for whom LQTS diagnostics had been requested during the period 1996-2005 at two clinical genetics centres (the University Medical Centre in Amsterdam and Maastricht University Hospital). The results were related to the postal code of the referred patient and corrected for the number of inhabitants of the region concerned.

RESULTS

A total of 421 potential LQTS probands were included. Corrected for the numbers of inhabitants in the various postal codes, the number of referrals varied from 3 per million to 110 per million inhabitants. In view of the most recent estimated prevalence of LQTS (1:2000), this means that only 15% ofthe carriers of the LQTS mutation have so far been detected.

CONCLUSION

There were large regional differences in the Netherlands in the requests for DNA diagnostics in patients with clinical LQTS. The overwhelming majority of the LQTS patients in the Netherlands have not yet been referred or identified. Expanding the available courses for general practitioners and cardiologists that are given by the staff of the cardiogenetic centres would seem to be indicated.