Background and Aims Implantable cardioverter-defibrillators (ICDs) are critical for preventing sudden cardiac death (SCD) in arrhythmogenic right ventricular cardiomyopathy (ARVC). This study aims to identify cross-continental differences in utilization of primary prevention ICDs and survival free from sustained ventricular arrhythmia (VA) in ARVC.Methods This was a retrospective analysis of ARVC patients without prior VA enrolled in clinical registries from 11 countries throughout Europe and North America. Patients were classified according to whether they received treatment in North America or Europe and were further stratified by baseline predicted VA risk into low- (<10%/5 years), intermediate- (10%-25%/5 years), and high-risk (>25%/5 years) groups. Differences in ICD implantation and survival free from sustained VA events (including appropriate ICD therapy) were assessed.Results One thousand ninety-eight patients were followed for a median of 5.1 years; 554 (50.5%) received a primary prevention ICD, and 286 (26.0%) experienced a first VA event. After adjusting for baseline risk factors, North Americans were more than three times as likely to receive ICDs {hazard ratio (HR) 3.1 [95% confidence interval (CI) 2.5, 3.8]} but had only mildly increased risk for incident sustained VA [HR 1.4 (95% CI 1.1, 1.8)]. North Americans without ICDs were at higher risk for incident sustained VA [HR 2.1 (95% CI 1.3, 3.4)] than Europeans.Conclusions North American ARVC patients were substantially more likely than Europeans to receive primary prevention ICDs across all arrhythmic risk strata. A lower rate of ICD implantation in Europe was not associated with a higher rate of VA events in those without ICDs.

Aims Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVC) is characterized by ventricular arrhythmias (VAs) and sudden cardiac death (SCD). We aimed to develop a model for individualized prediction of incident VA/SCD in ARVC patients. Methods and results Five hundred and twenty-eight patients with a definite diagnosis and no history of sustained VAs/SCD at baseline, aged 38.2 +/- 15.5 years, 44.7% male, were enrolled from five registries in North America and Europe. Over 4.83 (interquartile range 2.44-9.33) years of follow-up, 146 (27.7%) experienced sustained VA, defined as SCD, aborted SCD, sustained ventricular tachycardia, or appropriate implantable cardioverter-defibrillator (ICD) therapy. A prediction model estimating annual VA risk was developed using Cox regression with internal validation. Eight potential predictors were pre-specified: age, sex, cardiac syncope in the prior 6 months, non-sustained ventricular tachycardia, number of premature ventricular complexes in 24 h, number of leads with T-wave inversion, and right and left ventricular ejection fractions (LVEFs). All except LVEF were retained in the final model. The model accurately distinguished patients with and without events, with an optimism-corrected C-index of 0.77 [95% confidence interval (CI) 0.73-0.81] and minimal over-optimism [calibration slope of 0.93 (95% CI 0.92-0.95)]. By decision curve analysis, the clinical benefit of the model was superior to a current consensus-based ICD placement algorithm with a 20.3% reduction of ICD placements with the same proportion of protected patients (P < 0.001). Conclusion Using the Largest cohort of patients with ARVC and no prior VA, a prediction model using readily available clinical parameters was devised to estimate VA risk and guide decisions regarding primary prevention ICDs (www.arvcrisk.com).

Introduction: ARVC (Arrhythmogenic Right Ventricular Cardiomyopathy) is a heritable rare disease of the heart muscle, primarily affecting the right ventricle, that may cause arrhythmias and heart failure.

Aim: The overall aim of this thesis was to study various aspects of genetic information and electrocardiography (ECG), for their use in diagnosis and risk evaluation in ARVC.

Material and methods: Paper I: The genotype-phenotype correlations in four unrelated families with a plakophilin 2 gene variant (PKP2 c.2146-1C>G) were studied, to determine 1) to what extent family members fulfil diagnostic criteria and 2) to assess whether these gene carriers had any specific clinical characteristics in common. Paper II: Patients with definite ARVC but one group with and one without diagnostic ECG criteria were compared to each other and a healthy control group. Vectorcardiographic parameters were assessed alongside QRS duration, corrected QT interval and an angle measuring the upslope and downslope of the S wave (S-wave angle). Paper III: Combined Annotation Dependent Depletion (CADD, a bioinformatic tool) scores were calculated for all pathogenic and likely pathogenic variants in PKP2 found in patients from two ARVC Registries, and the scores association with arrhythmic events and age at definite ARVC diagnosis were assessed. Paper IV: Digital ECGs (n=6871) from 353 patients with definite ARVC were analysed using Glasgow algorithm to describe the longitudinal development of different ECG characteristics, but also to assess the relationship between the ECG parameters and 1) structural abnormalities and 2) sustained ventricular tachycardia (VT) during a 10-year follow-up.

Results: Paper I: In 41 family members evaluated, 23 were mutation carriers, and seven of them fulfilled diagnostic criteria. The clinical presentation was variable, and no specific genotype-phenotype correlation was found. Paper II: The vectorcardiographic parameters significantly differentiated the ARVC patients with normal ECGs from controls (p>0.004 to p<0.001). Paper III: In total, 33 unique genetic variants were reported in 179 patients. CADD score was neither associated with age at cardiac events (HR 1.002, 95% CI: 0.953-1.054, p=0.933) nor with age at definite ARVC diagnosis (HR 0.992, 95% CI: 0.947-1.039, p=0.731). Paper IV: Progressive changes in depolarisation and repolarisation parameters before as well as after the diagnosis was established confirming the progressive nature of ARVC developing over the course of decades, possibly in parallel with structural changes in the ventricles. The presence of T wave inversion in leads V3 or aVF at first ECG was significantly associated with ventricular tachycardia during 10 years follow-up (for lead V3 [HRadj 2.11, 95%CI 1.28-3.49, p=0.003], lead aVF [HRadj 1.68, 95%CI 1.02-2.77, p=.041] both adjusted for age, sex and proband status).

Conclusions: Our studies confirms previous results that, with our current knowledge, genetic variants in desmosomal genes are useful for diagnosis and cascade screening in family members but not for detailed risk stratification or prediction of diagnosis. Progressive changes in depolarisation and repolarisation ECG parameters before as well as after the diagnosis were established, confirming the progressive nature of ARVC developing over the course of decades, possibly in parallel with structural changes in the ventricles. Novel vectorcardiographic markers may aid in early detection of disease progression, possibly with biggest potential in cascade screening.

ARVC (Arrhythmogenic Right Ventricular Cardiomyopathy) är en relativt sällsynt och ärftlig hjärtmuskelsjukdom, som i sin klassiska form drabbar främst höger hjärtkammare (right ventricle). Det uppstår mikroskopiska skador i hjärtmuskeln, och dessa läker genom inlagring av ärrvävnad och fettceller. Med tiden påverkar denna process både hjärtmuskulaturens elektriska ledningsförmåga och dess förmåga att effektivt dra sig samman, vilket kan ge upphov till såväl rytmrubbningar (arytmier) som hjärtsvikt. I de mest dramatiska fallen kan kammarrytmrubbningarna leda till plötslig hjärtdöd, som kan vara det första symtomet. Det är därför av stor vikt att hitta individer som har sjukdomen och/eller bär på ett genetiskt anlag för sjukdomen tidigt, och värdera deras risk för arytmier. En svårighet i sammanhanget är att även om en individ bär på ett anlag för sjukdomen är det inte säkert att vederbörande någonsin får symtom eller hjärtmuskelförändringar, anlagen har mycket varierande grad av genomslag (penetrans). Det finns idag ingen specifik behandling för ARVC, men om symptom på hjärtsvikt eller hjärtrytmrubbningar uppträder behandlas dessa. Om risken för allvarlig hjärtrytmrubbning bedöms hög kan en ICD (Implantable Cardioverter Defibrillator, en så kallad hjärtstartare) opereras in.

Syftet med avhandlingen var att studera om och hur olika aspekter av genetisk information och EKG (elektrokardiografi) kan användas för diagnostik och riskvärdering.

I det första delarbetet studerade vi fyra familjer med en sjukdomsorsakande variant (tidigare kallad mutation) i den gen som kodar för proteinet plakofilin 2, för att se om det fanns något symtom eller sjukdomstecken som kan hjälpa oss att identifiera individer med genomslag av genen. Bland de 23 individerna som bar på genvarianten varierade graden av fynd och symtom påtagligt, och något gemensamt sjukdomstecken återfanns inte.

I det andra delarbetet använde vi oss av så kallad vektorkardiografi, som är ett sätt att beskriva hjärtats elektriska aktivitet i tre dimensioner, till skillnad från standard-EKG som tittar i två dimensioner. Målet var att se om vektorkardiografiska avläsningar, delvis på ett nytt sätt jämfört tidigare studier, kunde identifiera patienter med ARVC där klassiska sjukdomstecken på EKG saknades. Studien visar att det går att påvisa förändringar tidigare med tredimensionellt än med tvådimensionellt EKG. Metoden skulle kunna adderas i befintliga uppföljningsprogram för att identifiera patienter tidigt i sjukdomsförloppet.

Delarbete tre handlade åter om hjärtmuskelproteinet plakofilin 2, som tidigare beskrivits som i hög grad associerat med hjärtrytmstörningar. Ett poängberäkningssystem, CADD-score, har hittills använts för bedömning av genetiska avvikelsers svårighetsgrad och en värdering huruvida de är sjukdomsorsakande. En hög poäng innebär att proteinet bedöms påverkat i hög grad, och vi studerade om det innebar att individer med högre poäng på CADD-score fick mer rytmrubbningar eller diagnosen tidigare i livet än individer med låga poäng. Någon sådan koppling kunde inte ses, och slutsatsen blev att vi inte kan använda CADD-score för riskvärdering i det enskilda fallet.

Fjärde delarbetet kartlägger en stor grupp ARVC-patienters EKG-förändringar över tid. Vi beskriver hur olika delar av EKG-bilden förändras i relation till ålder men också i relation till tiden för diagnos, och kan visa att flera parametrar ändras signifikant med tiden. Vissa EKG-parametrars förändringar sammanfaller i tid med att avvikelser även ses vid undersökning med hjärtultraljud. Vi undersöker också om det finns någon enskild EKGförändring som, om den ses på det första EKG som tas på patienten, förutsäger en ökad risk för farliga hjärtrytmrubbningar under de kommande 10 åren. Två av EKG-förändringarna visade en sådan ökad risk, och vi diskuterar att dessa parametrar kanske framgent kan inkluderas i riskmodeller.

Sammanfattningsvis visar våra studier att genetiska analyser, som används för att hitta sjukdomsorsakande genetiska varianter hos patienter med ARVC för att i nästa steg identifiera riskindivider i familjen, med dagens kunskap inte kan hjälpa oss att avgöra en individs risk för allvarlig sjukdom och/eller hjärtrytmrubbning.

EKG, både två- som tredimensionellt, bidrar till såväl diagnostik som riskvärdering, och vår studie ger en unik bild av sjukdomens påverkan på olika EKG-parametrar över tid.

AIMS: Patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) have increased prevalence of atrial arrhythmias indicating atrial involvement in the disease. We aimed to assess the long-term evolution of P-wave indices as electrocardiographic (ECG) markers of atrial substrate during ARVC progression.

METHODS AND RESULTS: We included 100 patients with a definite ARVC diagnosis according to 2010 Task Force criteria [34% females, median age 41 (inter-quartile range 30-55) years]. All available sinus rhythm ECGs (n = 1504) were extracted from the regional electronic ECG databases and automatically processed using Glasgow algorithm. P-wave duration, P-wave area, P-wave frontal axis, and prevalence of abnormal P terminal force in lead V1 (aPTF-V1) were assessed and compared at ARVC diagnosis, 10 years before and up to 15 years after diagnosis.Prior to ARVC diagnosis, none of the P-wave indices differed significantly from the data at ARVC diagnosis. After ascertainment of ARVC diagnosis, P-wave area in lead V1 decreased from -1 to -30 µV ms at 5 years (P = 0.002). P-wave area in lead V2 decreased from 82 µV ms at ARVC diagnosis to 42 µV ms 10 years after ARVC diagnosis (P = 0.006). The prevalence of aPTF-V1 increased from 5% at ARVC diagnosis to 18% by the 15th year of follow-up (P = 0.004). P-wave duration and frontal axis did not change during disease progression.

CONCLUSION: Initial ARVC progression was associated with P-wave flattening in right precordial leads and in later disease stages an increased prevalence of aPTF-V1 was seen.

INTRODUCTION: Whether detailed genetic information contributes to risk stratification of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) remains uncertain. Pathogenic genetic variants in some genes seem to carry a higher risk for arrhythmia and earlier disease onset than others, but comparisons between variants in the same gene have not been done. Combined Annotation Dependent Depletion (CADD) score is a bioinformatics tool that measures the pathogenicity of each genetic variant. We hypothesized that a higher CADD score is associated with arrhythmic events and earlier age at ARVC manifestations in individuals carrying pathogenic or likely pathogenic genetic variants in plakophilin-2 (PKP2).

METHODS: CADD scores were calculated using the data from pooled Scandinavian and North American ARVC cohorts, and their association with cardiac events defined as ventricular tachycardia/ventricular fibrillation (VT/VF) or syncope and age at definite ARVC diagnosis were assessed.

RESULTS: In total, 33 unique genetic variants were reported in 179 patients (90 males, 71 probands, 96 with definite ARVC diagnosis at a median age of 35 years). Cardiac events were reported in 76 individuals (43%), of whom 53 had sustained VT/VF (35%). The CADD score was neither associated with age at cardiac events (HR 1.002, 95% CI: 0.953-1.054, p = 0.933) nor with age at definite ARVC diagnosis (HR 0.992, 95% CI: 0.947-1.039, p = 0.731).

CONCLUSION: No correlation was found between CADD scores and clinical manifestations of ARVC, indicating that the score has no additional risk stratification value among carriers of pathogenic or likely pathogenic PKP2 genetic variants.

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is associated with ventricular arrhythmias (VA) and sudden cardiac death (SCD). A model was recently developed to predict incident sustained VA in patients with ARVC. However, since this outcome may overestimate the risk for SCD, we aimed to specifically predict life-threatening VA (LTVA) as a closer surrogate for SCD.

Methods: We assembled a retrospective cohort of definite ARVC cases from 15 centers in North America and Europe. Association of 8 prespecified clinical predictors with LTVA (SCD, aborted SCD, sustained, or implantable cardioverter-defibrillator treated ventricular tachycardia >250 beats per minute) in follow-up was assessed by Cox regression with backward selection. Candidate variables included age, sex, prior sustained VA (≥30s, hemodynamically unstable, or implantable cardioverter-defibrillator treated ventricular tachycardia; or aborted SCD), syncope, 24-hour premature ventricular complexes count, the number of anterior and inferior leads with T-wave inversion, left and right ventricular ejection fraction. The resulting model was internally validated using bootstrapping.

Results: A total of 864 patients with definite ARVC (40±16 years; 53% male) were included. Over 5.75 years (interquartile range, 2.77-10.58) of follow-up, 93 (10.8%) patients experienced LTVA including 15 with SCD/aborted SCD (1.7%). Of the 8 prespecified clinical predictors, only 4 (younger age, male sex, premature ventricular complex count, and number of leads with T-wave inversion) were associated with LTVA. Notably, prior sustained VA did not predict subsequent LTVA (P=0.850). A model including only these 4 predictors had an optimism-corrected C-index of 0.74 (95% CI, 0.69-0.80) and calibration slope of 0.95 (95% CI, 0.94-0.98) indicating minimal over-optimism.

Conclusions: LTVA events in patients with ARVC can be predicted by a novel simple prediction model using only 4 clinical predictors. Prior sustained VA and the extent of functional heart disease are not associated with subsequent LTVA events.

Background: Recent studies in arrhythmogenic right ventricular cardiomyopathy (ARVC) patients have drawnattention to atrial fibrillation (AF) as an arrhythmic manifestation of ARVC and as an indicator of atrial involvement in the disease progression. We aimed to assess the prevalence of AF in the Scandinavian cohort of ARVC patients and to evaluate its association with disease clinical manifestations. Methods: Study sample comprised of 293 definite ARVC patients by 2010 Task Force criteria (TFC2010) and 141 genotype-positive family members (total n = 434, 43% females, median age at ARVC diagnosis 41 years [inter-quartile range (IQR) 28-52 years]). ARVC diagnostic score was calculated as the sum of major (2 points) and minor (1 point) criteria in all categories of the TFC2010. Results: AF was diagnosed in 42 patients (10%): in 41 patients with definite ARVC diagnosis (14%) vs in one genotype-positive familymember (1%), p amp;lt; 0.001. Themedian age at AF onsetwas 51 (IQR 38-58) years. The prevalence of AFwas related to the ARVC diagnostic score: it significantly increased startingwith the diagnostic score 4 (2% in those with score 3 vs 13% in those with score 4, p = 0.023) and increased further with increased diagnostic score (Somers d value is 0.074, p amp;lt; 0.001). Conclusion: AF is seen in 14% of definite ARVC patients and is related to the severity of disease phenotype thus suggesting AF being an arrhythmic manifestation of this cardiomyopathy indicating atrial myocardial involvement in the disease progression. (C) 2019 Elsevier B.V. All rights reserved.

Catheter ablation may reduce ventricular tachycardia (VT) burden in arrhythmogenic right ventricular cardiomyopathy (ARVC) patients. However, little is known about factors predicting need for ablation. Therefore, we sought to investigate predictors and use of VT ablation and to evaluate the postprocedural outcome in ARVC patients. We studied 435 patients from the Nordic ARVC registry including 220 probands with definite ARVC according to the 2010 task force criteria and 215 mutation-carrying relatives identified through cascade screening. Patients were followed until first-time VT ablation, death, heart transplantation, or January 1st 2018. Additionally, patients undergoing VT ablation were further followed from the time of ablation for recurrent ventricular arrhythmias. The cumulative use of VT ablation was 4% (95% confidence interval [CI] 3% to 6%) and 11% (95% CI 8% to 15%) after 1 and 10 years. All procedures were performed in probands in whom cumulative use was 8% (95% CI 5% to 12%) and 20% (95% CI 15% to 26%). In adjusted analyses among probands, only young age predicted ablation. In patients undergoing ablation, risk of recurrent arrhythmias was 59% (95% CI 44% to 71%) and 74% (95% CI 59% to 84%) 1 and 5 years after the procedure. Despite high recurrence rates, the burden of ventricular arrhythmias was reduced after ablation (p = 0.0042). Young age, use of several antiarrhythmic drugs and inducibility to VT after ablation were associated with an unfavorable outcome. In conclusion, twenty percent of ARVC probands developed a clinical indication for VT ablation within 10 years whereas mutation-carrying relatives were without such need. Although the burden of ventricular arrhythmias decreased after ablation, risk of recurrence was substantial. (C) 2019 Elsevier Inc. All rights reserved.

Myocarditis most often affects otherwise healthy athletes and is one of the leading causes of sudden death in children and young adults. Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetically determined heart muscle disorder with increased risk for paroxysmal ventricular arrhythmias and sudden cardiac death. The clinical picture of myocarditis and ARVC may overlap during the early stages of cardiomyopathy, which may lead to misdiagnosis. In the literature, we found several cases that presented with episodes of myocarditis and ended up with a diagnosis of arrhythmogenic cardiomyopathy, mostly of the left predominant type. The aim of this case presentation is to shed light upon a possible link between myocarditis, a desmoplakin (DSP) gene variant, and ARVC by describing a case of male monozygotic twins who presented with symptoms and signs of myocarditis at 17 and 18 years of age, respectively. One of them also had a recurrent episode of myocarditis. The twins and their family were extensively examined including electrocardiograms (ECG), biochemistry, multimodal cardiac imaging, myocardial biopsy, genetic analysis, repeated cardiac magnetic resonance (CMR) and echocardiography over time. Both twins presented with chest pain, ECG with slight ST-T elevation, and increased troponin T levels. CMR demonstrated an affected left ventricle with comprehensive inflammatory, subepicardial changes consistent with myocarditis. The right ventricle did not appear to have any abnormalities. Genotype analysis revealed a nonsense heterozygous variant in the desmoplakin (DSP) gene [NM_004415.2:c.2521_2522del (p.Gln841Aspfs*9)] that is considered likely pathogenic and presumably ARVC related. There was no previous family history of heart disease. There might be a common pathophysiology of ARVC, associated with desmosomal dysfunction, and myocarditis. In our case, both twins have an affected left ventricle without any right ventricular involvement, and they are carriers of a novel DSP variant that is likely associated with ARVC. The extensive inflammation of the LV that was apparent in the CMR may or may not be the primary event of ARVC. Nevertheless, our data suggest that irrespective of a possible link here to ARVC, genetic testing for arrhythmogenic cardiomyopathy might be advisable for patients with recurrent myocarditis associated with a family history of myocarditis.

AIMS: Women with arrhythmogenic right ventricular cardiomyopathy (ARVC) are at relatively lower risk of ventricular arrhythmias (VAs) than men, but the physical burden associated with pregnancy on VA risk remains insufficiently studied. We aimed to assess the risk of VA in relation to pregnancies in women with ARVC.

METHODS AND RESULTS: We included 199 females with definite ARVC (n = 121) and mutation-positive family members without ascertained ARVC diagnosis (n = 78), of whom 120 had at least one childbirth. Ventricular arrhythmia-free survival after the latest childbirth was compared between women with one (n = 20), two (n = 67), and three or more (n = 37) childbirths. Cumulative probability of VA for each pregnancy (n = 261) was assessed from conception through 2 years after childbirth and compared between those pregnancies that occurred before (n = 191) or after (n = 19) ARVC diagnosis and in mutation-positive family members (n = 51). The nulliparous women had lower median age at ARVC diagnosis (38 vs. 42 years, P < 0.001) and first VA (22 vs. 41 years, P < 0.001). Ventricular arrhythmia-free survival after the latest childbirth was not related to the number of pregnancies. No pregnancy-related VA was reported among the family members. Women who gave birth after ARVC diagnosis had elevated risk of VA postpartum (hazard ratio 13.74, 95% confidence interval 2.9-63, P = 0.001), though only two events occurred during pregnancies.

CONCLUSION: In women with ARVC, pregnancy was uneventful for the overwhelming majority and the number of prior completed pregnancies was not associated with VA risk. Pregnancy-related VA was primarily related to the phenotypical severity rather than pregnancy itself.