Electroanatomical voltage mapping with contact force sensing for diagnosis of arrhythmogenic right ventricular cardiomyopathy

BACKGROUND

Three-dimensional electroanatomical mapping (EAM) can be helpful to diagnose arrhythmogenic right ventricular cardiomyopathy (ARVC). Yet, previous studies utilizing EAM have not systematically used contact-force sensing catheters (CFSC) to characterize the substrate in ARVC, which is the current gold standard to assure adequate tissue contact.

OBJECTIVE

To investigate reference values for endocardial right ventricular (RV) EAM as well as substrate characterization in patients with ARVC by using CFSC.

METHODS

Endocardial RV EAM during sinus rhythm was performed with CFSC in 12 patients with definite ARVC and 5 matched controls without structural heart disease. A subanalysis for the RV outflow tract (RVOT), septum, free-wall, subtricuspid region, and apex was performed. Endocardial bipolar and unipolar voltage amplitudes (BVA, UVA), signal characteristics and duration as well as the impact of catheter orientation on endocardial signals were also investigated.

RESULTS

ARVC patients showed lower BVA vs. controls (p = 0.018), particularly in the subtricuspid region (1.4, IQR:0.5-3.1 vs. 3.8, IQR:2.5-5 mV, p = 0.037) and RV apex (2.5, IQR:1.5-4 vs. 4.3,IQR:2.9-6.1 mV, p = 0.019). BVA in all RV regions yielded a high sensitivity and specificity for ARVC diagnosis (AUC 59-78%, p < 0.05 for all), with the highest performance for the subtricuspid region (AUC 78%, 95% CI:0.75-0.81, p < 0.001, negative predictive value 100%). A positive correlation between BVA and an orthogonal catheter orientation (46°-90°:r = 0.106, p < 0.001), and a negative correlation between BVA and EGM duration (r = -0.370, p < 0.001) was found.

CONCLUSIONS

EAM using CFSC validates previous bipolar cut-off values for normal endocardial RV voltage amplitudes. RV voltages are generally lower in ARVC as compared to controls, with the subtricuspid area being commonly affected and having the highest discriminatory power to differentiate between ARVC and healthy controls. Therefore, EAM using CFSC constitutes a promising tool for diagnosis of ARVC.

3D atrial strain for prediction of atrial fibrillation recurrence

Introduction

Atrial fibrillation (AF) is one of the most common supraventricular arrhythmias. Treatment options apart from medication include interventional catheter-guided pulmonary vein isolation (PVI). However, there is limited knowledge about factors predicting arrhythmia recurrence after PVI.

Aim

To study the association of 3-dimensional (3D) left atrial (LA) strain (LAS) and 3D electro-anatomical voltage mapping (EAVM) with early recurrence of AF after PVI.

Methods

In this prospective single center study, 93 patients undergoing PVI were enrolled between December 2018 and October 2021. All patients underwent an echocardiographic examination within two weeks before PVI using the Canon Aplio i900 system to analyse LAS from 3D LA volume. A 3D EAVM was obtained using high-density mapping catheters during PVI. The CARTO 3 system (Version V6-V7) was used for determining LA scar area by low voltage mapping (local amplitude &lt;0.5 mV) indicated as percentage (EAVM-%). Follow-up time points were set at 2, 3, 6 and 12 months to investigate recurrence of AF, with exclusion of events occurring during the first two months (blanking phase).

Results

During follow-up, 12 out of 93 patients experienced recurrence of AF (12.9%; AF-Group). Baseline characteristics did not differ between AF-Group and Non-AF-Group. In contrast, LAS was significantly impaired in the AF-Group (median −4.6, IQR [−5.6 to −3.6]) when compared to the Non-AF-Group (−6.2 [−8.3 to −4.5]; p=0.009). The EAVM-% did not differ between the groups (AF-Group: 5.0 [1.5 to 21.5]; Non-AF-Group: 4.4 [1.5 to 15.9]; p=0.710). No significant correlations were found between LAS and EAVM-% (r=0.03, p=0.812). A cut-off value of −5.89% for LAS had a sensitivity of 100% and a specificity of 57% for AF recurrence (AUC=70%; p&lt;0.001). Kaplan Meier curves for event-free survival were generated based on the LAS cut-off demonstrating excellent differentiation of those with and without AF recurrence (p&lt;0.001; see figure). Furthermore, LAS was associated with an increased risk of early AF recurrence (HR 1.40, IQR [1.02–1.92], p=0.040), while EAVM-% was not (HR 0.99 [0.95–1.04], p=0.787).

Conclusion

3D LAS was associated with an increased risk of early AF recurrence after PVI, while EAVM-% was not. 3D LAS might be used for identifying patients who would benefit from PVI.

Funding Acknowledgement

Type of funding sources: None.

Identifying proteomic profiles as indicators of disease severity in arrhythmogenic cardiomyopathy

Introduction

Arrhythmogenic cardiomyopathy (ACM) is an inherited heart muscle disease characterized by progressive fibrofatty replacement of the myocardium and ventricular arrhythmias. Biventricular (BiV) involvement may lead to heart failure. This study aimed to investigate characteristic proteomic patterns in plasma of ACM patients, and correlated them with clinical outcome as well as physical exercise, to assess if key soluble molecules may serve as specific biomarkers for ACM, and whether mechanical stress induced by physical exercise may alter proteomic patterns in ACM patients.

Methods

In 38 ACM patients clinical parameters and major adverse cardiovascular events (MACE defined as presence of sustained ventricular tachycardia, ventricular fibrillation, appropriate therapy from implantable cardioverter defibrillator, sudden cardiac death, death related to end-stage heart failure or cardiac transplant) were obtained prospectively during a mean follow-up period of 36 months. All patients received genetic testing using next generation DNA sequencing. Plasma protein expression was analysed using the Proximity Extension Assay (PEA) technology, where a pair of oligonucleotide-labelled antibody probe binds to each targeted protein. In a subgroup of 11 patients blood was drawn immediately before and 3 hours after standardised bicycle exercise testing, and plasma protein expression was compared.

Results

12 patients had ACM with BiV involvement, and 26 patients had isolated right ventricular (RV) involvement. During the follow-up period, 34 patients had a MACE (30% with RV and 14% with BiV). Over 360 proteins were assessed in all ACM patients and compared to 24 healthy controls. The proteomic signature of ACM patients differed significantly compared to controls, and 32 proteins were upregulated in ACM (Figure 1). The proteomic profiles of patients with RV involvement also differed from those with BiV involvement. Most importantly, after exercise, over 40 proteins were upregulated specifically in ACM patients compared to controls, including key pro-inflammatory, adipogenic molecules and also markers of cardiac fibrosis.

Conclusion

Our study shows that ACM patients with RV and BiV involvement have different plasma proteomic profiles compared to healthy controls. Furthermore we were able to demonstrate that, specifically in ACM patients, several pro-inflammatory pathways are upregulated after exercise compared to healthy controls, further elucidating the molecular pathways associated with arrhythmogenicity and disease progression and highlighting the key role of physical stress. Our results may enable the identification of potential future biomarkers for diagnosis and risk stratification and may pave the way for personalized patient specific treatments.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Baugarten Foundation ZurichSwiss National Foundation

Leadless pacemaker implantation after transcatheter aortic valve replacement

Funding Acknowledgements

Type of funding sources: None.

Background

Impairment of the conduction system may occur in 9-30 % of patients undergoing transcatheter aortic valve replacement (TAVR). Since this is typically an elderly and frail patient population, leadless pacing potentially offers benefits over conventional transvenous pacemaker devices. However, available efficacy and safety outcome data of leadless pacing in a population who underwent a TAVR procedure is still limited.

Purpose

Retrospective analysis of efficacy and safety outcome data in patients who underwent leadless pacemaker implantation after TAVR due to relevant bradycardias.

Methods and Results

In this retrospective analysis from two large Swiss implantation centres, 257 consecutive patients undergoing leadless pacemaker were included. Of the total cohort, 26 subjects had a previous TAVR complicated by early (within 30 days)- or late-onset (after 30 days) bradycardias (Table 1). The TAVR group did not differ compared to the non-TAVR with regard to age, gender and left-ventricular ejection fraction (LVEF). Median duration between valve intervention and leadless pacemaker implantation was 8 days (range 0 to 368 days). After a TAVR procedure, left femoral access was chosen in 30.8% (8 of 26 of cases) for the leadless pacemaker implantation as compared to 5.2% (12 of 231 of the cases) in the remaining population (P &lt; 0.01). Mean implantation duration was 56 ± 22 min in the TAVR group compared to 48 ± 20 min (P = NS) and a successful implantation rate of 100.0 % in the TAVR group vs 98.7% in the remaining population (P = NS). There were no significant differences in pacing parameters (sensing, impedance and threshold, respectively) between the two groups. A total of eight major periprocedural complications (3.1%) were encountered in the entire cohort within 30 days, of which one (pericardial effusion) occurred in the TAVR population (P = 0.04), which was managed conservatively with pericardiocentesis.

Conclusions

Leadless pacemaker implantation appears to be safe and effective in patients after TAVR in need of antibradycardia pacing.

Leadless pacemaker implantation in patients with a previous transvenous device

Funding Acknowledgements

Type of funding sources: None.

Background

Leadless pacing has been established as an alternative approach to transvenous devices for selected patients suffering from bradycardias. While in the majority of cases leadless pacemaker implantation represents a de novo procedure, in an increasing number of patients such a device is used after a previously implanted transvenous pacemaker.

Purpose

Retrospective analysis of the efficacy and safety outcome in patients who underwent leadless pacemaker implantation in the context of a previously implanted conventional pacemaker.

Methods and Results

In this retrospective analysis from two large Swiss implantation centres, 257 consecutive patients undergoing leadless pacemaker implantation were included. Of the total cohort, 233 patients were diagnosed with new-onset bradycardias, while in 24 patients a prior transvenous device was present. Out of these 24 patients, 20 subjects required lead extraction of the previous system due to infection (70%, 14 patients), malfunction or other reasons (Table 1). In 3 patients with device-related infection, lead extraction and leadless pacemaker implantation were performed as a single procedure, while in the remaining 11 cases a time window between the two procedures was present (median of 11.5 days with a range of 2 to 186 days). In the population with a previous device, mean age at implantation was 81 ± 9 years which did not differ compared to the de novo cohort. Mean implantation duration was 57 ± 31 minutes in the cohort with a previous device versus 48 ± 191 minutes in the de novo population without a significant difference (P=NS) and with a successful implantation rate of 100% versus 98.7% in the de novo population (P=NS). Electrical device parameters (sensing, impedance, threshold) at implantation and during follow-up (mean 12.5 ± 9.3 months) were similar between the two groups. Eight major periprocedural complications (3.1%) were encountered (4 pericardial effusions, 3 femoral bleedings and 1 intra-abdominal bleeding) in the entire cohort within a 30 days period, of which the majority occurred in the de novo cohort (75 %, 6 of 8). A total of 4 pericardial effusions occurred, which could be managed without the need for cardiac surgery. The were no reinfections registered after leadless pacemaker implantation during follow-up.

Conclusions

Implantation of a leadless pacemaker in patients with a prior conventional system (with or without extraction of the previous device) was effective and safe in our population of patients.

A novel variant in the SLC4A3 gene with high penetrance in a family with short QT Syndrome

Funding Acknowledgements

Type of funding sources: None.

Background

Short QT syndrome (SQTS) is a rare, autosomal dominant disease causing sudden cardiac death (SCD). Current guidelines recommend genetic testing. Associated variants in KCNQ1, KCNH2, KCNJ2 and SLC4A3 genes have been reported.

Purpose

We report a family with a variant in the SLC4A3 gene with several presentations of SCD and high clinical penetrance of SQTS.

Methods

We performed a post-mortem genetic testing in the index patient in whom prior ECG was available. Subsequently, clinical and electrophysiological work-up and cascade screening (CS) of the detected suspected variant was carried out in available relatives.

Results

The index patient had suffered a SCD at the age of 17 (figure, upper panel, arrow). A previously registered ECG showed a shortened QTc of 340ms (figure, lower panel). Autopsy revealed no structural heart disease. Post-mortem genetic testing revealed variants in the LDB3, MYH7 and a novel heterozygous missense variant, p.(Ser1039Arg) also in the SLC4A3 gene. Although predictive bioinformatic algorithms (AlignGVGD, SIFT, MutationTaster, Polyphen2) showed conflicting classifications, family history was notable for SCD without post-mortem genetic work-up in three second degree relatives (figure, upper panel, patients 207, 208 and 305, age of death 33, 25 and 33 years respectively). CS was performed in first and second degree relatives of the index patient and was highly suggestive for disease association of the variant in the SLC4A3 gene with co-segregation in all clinically affected family members. Only one patient with the variant had a normal QTc (figure, upper panel, patient 202) of 407ms, however this patient was on regular QT-prolonging medication (risperidone and loperamide).

Conclusion

Genetic testing revealed a novel in the SLC4A3 gene, which was recently implicated in the pathogenesis of the SQTS. Although predictive bioinformatic algorithms yielded conflicting results, CS of family members suggests a likely pathogenicity (class IV) of the variant. Further CS or functional tests are necessary to establish causality. Abstract Figure. ECG of index patient and family tree

Anti-desmoglein2 autoantibodies are present in patients with cardiac sarcoidosis and correlate with cardiac inflammation

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): The Zurich ACM Program is supported by generous grants from the Georg and Bertha Schwyzer-Winniker Foundation, the Baugarten Foundation, Swiss National Science Foundation, Swiss Heart Foundation and Wild Foundation. This work is also supported by a Canadian Institutes of Health Research grant (FRN: 162402) and the Labatt Heart Centre and Waugh Family Innovation Funds, Caitlin Elizabeth Morris Memorial Fund, Alex Corrance Memorial Foundation and Meredith Cartwright.

BACKGROUND Arrhythmogenic right ventricular cardiomyopathy (ARVC) has several phenocopies such as cardiac sarcoidosis (CS), idiopathic outflow tract ventricular tachycardia (OT-VT) and myocarditis. Differentiation between these entities can be challenging. Recently, we have identified diagnostic anti-desmoglein-2 autoantibodies (anti-DSG2 Abs) in patients with ARVC.

PURPOSE We sought to examine whether anti-DSG2 Abs are also present in clinical phenocopies of ARVC.

METHODS Anti-DSG2 Abs in sera of 25, 19 and 22 patients with sarcoidosis, OT-VT and myocarditis, respectively, were assessed by western blots and ELISA. Clinical and imaging parameters, as well as conventional biomarkers were correlated to detected anti-DSG2 Ab intensity levels.

RESULTS Anti-DSG2 Abs, at various intensities, were identified in 6/25 (24%) patients with sarcoidosis, all presenting with CS, but were absent in patients with OT-VT and myocarditis. Cardiac 18F- fluorodeoxyglucose positron emission tomography (18F-FDG PET) was positive in all sarcoidosis patients with positive anti-DSG2 Abs, corresponding to a median PET maximum standardized uptake value (SUVmax) of 5.65 [IQR: 5.15 – 10.9]. In sarcoidosis patients without anti-DSG2 Abs, the SUVmax values were significantly lower with a median of 0 [IQR: 0 – 4] (p = 0.011). The Pearson correlation coefficient (R) was 0.188 (p = 0.039) indicating a positive correlation between cardiac 18F-FDG uptake and anti-DSG2 Abs. No significant correlation was detected for any of the other clinical parameters and biomarkers.

CONCLUSIONS In addition to being present in ARVC, anti-DSG2 Abs are also found in CS, a common phenocopy of ARVC; conversely, anti-DSG2 Abs are absent in idiopathic OT-VT and myocarditis. Anti-DSG2 Ab levels positively correlate with myocardial disease activity in CS as indicated by cardiac 18F-FDG PET scanning. Abstract Figure. Central illustration

Functional characterization of drug responses in induced pluripotent stem cell-derived cardiomyocytes from a short QT syndrome type 5 patient

Funding Acknowledgements

Type of funding sources: Other. Main funding source(s): ETH Zurich Personalized Health and Related Technologies; German Centre for Cardiovascular Research

Introduction

Short QT syndrome (SQTS) and Brugada syndrome (BrS) are rare channelopathies causing sudden cardiac death (SCD). There are only few investigations of effective therapies of SQTS and BrS linked to CACNB2 variants. Since treatment data of SQTS are sparse, we studied drug responses of induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM) 2D cultures carrying a mutation in the CACNB2 gene from a SQTS type 5 (SQT5) patient with an established phenotype. We used high-density microelectrode arrays (HD-MEAs), patch clamp, and calcium-transient imaging.

Purpose

To investigate the electrophysiological responses of SQT5 patient-derived iPSC-CMs upon exposure to antiarrhythmic drugs.

Methods

Human iPSCs, derived from a SQT5 patient and a healthy donor, were cultured and differentiated into cardiomyocytes by temporal modulation of the Wnt signaling. For electrophysiological measurements, spontaneously beating cardiomyocytes at day 40-60 were dissociated and plated a) on petri dishes for patch clamp and calcium-transient measurements and b) directly on HD-MEAs. Antiarrhythmic drugs, including sotalol, quinidine, and flecainide, were dosed to the cells after plating as soon as stable activity levels were measured. After baseline measurements, drug doses were sequentially increased from low to high concentrations.

Results

We observed spontaneous and synchronous beating of SQT5 patient- and healthy donor-derived iPSC-CMs. Quinidine, which is known to be effective for treatment of SQTS with possible differences for subtypes, prolonged field-potential duration (FPD) and action-potential duration in SQT5 patient-derived iPSC-CMs. Sotalol slightly increased FPD at 30µM as measured with HD-MEAs, whereas action-potential duration (APD) measured through patch clamp did not exhibit a notable effect at 30 µM. APD became shorter at higher concentrations, which is in line with clinical data of SQTS patients. HD-MEA measurements showed that flecainide shortened the FPD of SQT5 patient-derived CMs at 20µM. For healthy donor-derived iPSC-CMs, quinidine, sotalol, and flecainide prolonged FPDs in HD-MEA measurements. Using calcium-transient imaging, quinidine showed a slight antiarrhythmic effect, whereas sotalol did not have antiarrhythmic effects.

Conclusion

We used HD-MEAs, patch clamp, and calcium-transient imaging to analyze electrophysiological responses of SQT5 patient-derived iPSC-CMs upon dosage of antiarrhythmic drugs. Our preliminary results show that quinidine - but not flecainide - could prolong the repolarization duration in SQT5 patient-derived iPSC-CMs.

A novel diagnostic score to differentiate between athlete"s heart and ARVC

Funding Acknowledgements

Type of funding sources: None.

Background

The 2010 Task Force Criteria (TFC), although representing the current gold standard to diagnose arrhythmogenic right ventricular cardiomyopathy (ARVC), have not been tested to differentiate ARVC from the athlete’s heart. Furthermore, not all 6 diagnostic categories are easy to obtain.

Purpose

We hypothesized that atrial dimensions are useful to differentiate between both entities. Therefore, we developed a new diagnostic score based upon readily available clinical parameters including atrial dimensions on TTE to help distinguishing the athlete’s heart from ARVC in daily clinical practice.

Methods

In this observational study, 37 patients with definite ARVC (from the Zurich ARVC Program) were compared to 68 athletes. Base on ROC analysis, the following echocardiographic, laboratory and electrocardiographic parameters were included in the final score: indexed right/left atrial volumes (RAVI/LAVI ratio), NT-proBNP, RVOT measurements (PLAX and PSAX adjusted for BSA) on TTE, tricuspid annular motion velocity (TAM) on TTE, precordial electrocardiographic T-wave inversions and depolarization abnormalities according to the TFC.

Results

ARVC patients had a higher RAVI/LAVI ratio (1.78 ± 1.6vs0.95 ± 0.3,p &lt; 0.001), lower right-ventricular function (fac:28 ± 9.7vs42.1 ± 4.8%,p &lt; 0.001; TAM:17.9 ± 5.6vs23.3 ± 3.7mm,p &lt; 0.001) and higher serum NT-proBNP levels (491 ± 771vs44.8 ± 50.6ng/l,p &lt; 0.001). Our novel score outperformed the performance of the 2010 TFC using those parameters, which are available in routine clinical practice (AUC95%,p &lt; 0.001(95%CI.91-.99)vs.AUC90%,p &lt; 0.001(95%CI.84-.97). A score value of 7/12 points yielded a specificity of 98% and a sensitivity of 61% for a diagnosis of ARVC.

Conclusions

ARVC patients present with significantly larger RA as compared to athletes, resulting in a greater RAVI/LAVI ratio. Our novel diagnostic score includes readily available clinical parameters and has a high diagnostic accuracy to differentiate between ARVC and the athlete´s heart. Abstract Figure. Novel clinical score

911Which patients are most likely to benefit from the wearable cardioverter-defibrillator? Findings from the Swiss WCD registry

OnBehalf

Swiss WCD Registry

Introduction

 The wearable cardioverter-defibrillator (WCD) has established itself as a temporary protection from sudden arrhythmogenic death in selected patients at risk. However, it is still of debate which patients and for what duration benefit from its use. Therefore, appropriate patient selection is key. Purpose: This study reports the results of the Swiss WCD registry with an emphasis on implantable cardioverter-defibrillator (ICD) implantation rate and ICD therapies.

Methods

 We retrospectively reviewed the indications, baseline characteristics and administered therapies in patients prescribed a WCD at 12 participating centers rom 2014 until 2018 in Switzerland. Further data on medical therapy, WCD therapy adherence, and ICD implantation rates were collected. 

Results

 456 patients were included in our study comprising of 66% of all Swiss patients prescribed a WCD in the examined time period. The mean age was 57 ±14 years, 18% were female and the mean ejection fraction (EF) was 32% ± 13. Indications for WCD use and appropriate shock rate are shown in the figure. Patients wore the WCD over a median of 58 days (range 1-455) with a median daily average wear-time of 22.6 hours (range 0.6-23.8). 17 appropriate therapies were administered by the WCD to a total of 12 patients leading to a therapy rate of 2.6% over a median wear-time of 16 days (range 2-79) and to a therapy rate of 3.9% in patients with ischemic cardiomyopathy (ICM) with an EF ≤35%. ICM with an EF ≤35% and bridging to ICD-implantation or heart transplantation as indication for WCD prescription were significantly associated with an appropriate therapy (p = 0.046 and 0.003, respectively). One patient with non-ischemic cardiomyopathy (NICM) received an appropriate therapy (0.8%). The mean EF in patients receiving an appropriate therapy by the WCD was also significantly lower (p = 0.04). No patient with wearing the WCD for congenital/inherited heart disease or risk stratification with an EF &gt;35% had a therapy administered by the WCD. There were no inappropriate therapies during the investigated time period. After cessation of WCD use EF improved to 38% ±13; ultimately, 212 patients (46%) were implanted with an ICD. During a follow-up of 476 days (range 7-2347) 22 (9.8%) patients received an appropriate therapy by their ICD. Four of the 22 had prior appropriate therapy by the WCD.

Conclusions

 ICM with severely reduced EF was the most common indication for WCD use leading to a high rate of appropriate therapy by the WCD. This, however, did not translate in a higher rate of appropriate ICD-therapies during follow-up in this subpopulation possibly due to significant improvements in their ejection fractions. Patients with NICM or congenital/inherited heart disease seldom had an appropriate therapy by the WCD.

Abstract Figure. Indications for WCD use and therapy rate

1268A family with a novel variant in the SLC4A3 gene leading to short QT phenotype - the importance of whole-exome-sequencing and cascade screening

Funding Acknowledgements

none

Introduction

 Short QT syndrome (SQTS) is a rare, autosomal dominant disease causing ventricular fibrillation and sudden cardiac death. Genetic testing is recommended according to current guidelines. Mutations in KCNQ1, KCNH2, KCNJ2 and more recently SLC4A3 genes have been implicated in SQTS. These genes encode potassium channel subunits and a bicarbonate transporter regulating intracellular pH. A dominant mutation in this transporter can lead to increased intracellular pH and shortened action potential.

Purpose

 We present a family with a short QT phenotype and recurrent syncope in whom a novel genetic variant was detected by whole-exome sequencing (WES), confirmed by cascade screening.

Methods

 We performed a thorough work-up of the index patient including medical history, physical examination, 12-lead ECG, echocardiography, stress testing, coronary angiography, flecainide challenge, and genetic testing with NGS. QTc was determined using Bazett’s formula. CS of all 1° and two 2° relatives was performed.

Results

 The ECG of the index patient showed a QTc of 340ms and characteristics compatible with a SQTS (figure). Clinical work-up was unremarkable. A first genetic search with next generation sequencing focusing on genes that have been previously involved in the pathogenesis of channelopathies detected a rare known heterozygous missense variant in the KCNH2 gene (Arg328Cys, frequency 0.053%), which was predicted to be pathogenic according to various prediction algorithms (Polyphen, SIFT, Align GVGD, mutation taster). ECG screening of all asymptomatic first-degree family members identified a SQT phenotype in the mother (QTc 355ms), but not in the father (QTc 380ms) and sister (410ms). The KCNH2 variant was found in the father and sister but not the affected mother, which excludes this variant as the causative mutation in this family. Therefore, reanalysis of WES data was performed and revealed a novel heterozygous missense variant p.(Arg370Cys) in the SLC4A3 gene, recently associated with SQTS. A mutation in this gene at the same position has been previously reported in SQTS. The p.(Arg370Cys) mutation was found in the mother but not in the unaffected father or sister. Furthermore the mutation was present in two affected maternal uncles (QTc 319ms and 342ms) supporting the assumption that this was the causative mutation in this family.

Conclusions

 A novel genetic variant in the SLC4A3 gene leading to sQT phenotype could be detected using WES and cascade screening. Predictive bioinformatic algorithms to assess the pathogenicity of missense variants are of limited relevance, but genetic analysis of additional unaffected and affected family members may be instrumental to identify pathogenic DNA sequence variations.

Abstract Figure. Pedigree and ECGs of the family

P3689Association of echocardiographic progression and genetic profile in arrhythmogenic right ventricular cardiomyopathy

Background

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is frequently associated with mutations in genes coding for desmosomal proteins. In this study, we investigated the association of genetic status with ARVC progression as defined by echocardiographic parameters.

Methods

We tested 62 ARVC patients for their genetic profile. Accordingly, they were grouped in mutation positive (48 (77%) patients; median age 48.5 years; 33 (69%) males), and mutation negative (14 (23%) patients; median age 45 years; 10 (71%) males). Prevalent mutations were Desmoglein-2 (DSG2) in 16 (26%), Desmoplakin (DSP) in 14 (23%), and Plakophilin-2 (PKP2) in 9 (15%) patients.

Results

At baseline, there were no significant differences in clinical characteristics between the two groups. Patients were followed-up for a median time period of 1420 days, and there was no significant difference in the duration of follow-up between the two groups (p=0.05).

In the mutation positive group, there was a significant increase in right ventricular end-diastolic area (p=0.002), right atrial short (p=0.008) and long (p=0.002) diameter, left atrial diameter (p=0.014), and a decrease in left ventricular ejection fraction (p=0.014) during follow up. Right ventricular functial parameters did not change significantly (tricuspid annular plane systolic excursion: p=0.24; fractional area change: p=0.088).

In the mutation negative group, none of the aforementioned echocardiographic findings exhibited any significant difference during follow-up: right ventricular end-diastolic area (p=0.1); right atrial short (p=0.7) and long (p=0.9) diameter, left atrial diameter (p=0.6), and left ventricular ejection fraction (p=0.3). Similarly, right ventricular functional parameters did not change significantly (tricuspid annular plane systolic excursion: p=0.77; fractional area change: p=0.80. Results are summarized in the figure.

Change in echocardiographic findings.

Conclusions

There is a strong association between echocardiographic progression of ARVC phenotype and the presence of a pathogenic mutation. Such mutations should be searched in all patients with an ARVC phenotype, and mutation positive individuals should be followed-up in shorter intervals.

Multiple clinical profiles of families with the short QT syndrome

Aims

Short QT syndrome (SQTS) is a rare cardiac channelopathy characterized by a shortened corrected QT (QTc)-interval that can lead to ventricular arrhythmias and sudden cardiac death. The aim of this study was to investigate the clinical phenotypes and long-term outcomes of three families harbouring genetic mutations associated with the SQTS.

Methods and results

Clinical data included medical history, physical examination, 12-lead ECG, 24-h Holter-ECG, and transthoracic echocardiography from three index patients and their first-degree relatives. Next generation clinical exome sequencing and genetic cascade screening were performed in index patients and their relatives, respectively. Two index patients experienced malignant ventricular arrhythmias and one patient suffered from arrhythmogenic syncope during a median follow-up period of 8 years. They all had genetic mutations associated with the SQTS. Two mutations were found in the KCNH2 gene, and one in the CACNA2D gene. One patient had an additional SCN10A variant. Alive and mutation-positive family members had short QTc-intervals, but no further phenotypic manifestations. None of the mutation-negative family members had an abnormal ECG or any symptoms. In all patients with shortened QTc-intervals, the QTc-interval had a low long-term variability and QTc shortening always remained detectable by 12-lead ECG.

Conclusion

This study shows the variety of phenotypic manifestations in different families with SQTS. It further emphasizes the importance of a 12-lead ECG for early diagnosis, and the utility of next generation sequencing for the identification of mutations associated with the SQTS.

Risk factors promoting hypertensive crises: evidence from a longitudinal study

BACKGROUND

Current knowledge about risk factors promoting hypertensive crisis originates from retrospective data. Therefore, potential risk factors of hypertensive crisis were assessed in a prospective longitudinal study.

METHODS

Eighty-nine patients of the medical outpatient unit at the University Hospital of Bern (Bern, Switzerland) with previously diagnosed hypertension participated in this study. At baseline, 33 potential risk factors were assessed. All patients were followed-up for the outcome of hypertensive crisis. Cox regression models were used to detect relationships between risk factors and hypertensive crisis (defined as acute rise of systolic blood pressure (BP) > or =200 mm Hg and/or diastolic BP > or =120 mm Hg).

RESULTS

The mean duration of follow-up was 1.6 +/- 0.3 years (range 1.0-2.4 years). Four patients (4.5%) were lost to follow-up. Thirteen patients (15.3%) experienced hypertensive crisis during follow-up. Several potential risk factors were significantly associated with hypertensive crisis: female sex, higher grades of obesity, the presence of a hypertensive or coronary heart disease, the presence of a somatoform disorder, a higher number of antihypertensive drugs, and nonadherence to medication. As measured by the hazard ratio, nonadherence was the most important factor associated with hypertensive crisis (hazard ratio 5.88, 95% confidence interval 1.59-21.77, P < 0.01).

CONCLUSIONS

This study identified several potential risk factors of hypertensive crisis. Results of this study are consistent with the hypothesis that improvement of medical adherence in antihypertensive therapy would help to prevent hypertensive crises. However, larger studies are needed to assess potential confounding, other risk factors and the possibility of interaction between predictors.