Finding a cause in sudden cardiac arrest survivors: Getting the testing right.

Sudden cardiac arrest (SCA) survivors are optimally managed by a multidisciplinary team with expertise in cardiac electrophysiology and cardiac genetics with the capacity to deal with both the medical and psychological needs of patients and their families. Consideration is given to an appropriate selection of second-line investigation, genetic testing, and cascade testing.

Analysis of athlete QT intervals by age: Fridericia and Hodges heart rate corrections outperform Bazett for athlete ECG screening.

BACKGROUND: Cardiac screening of elite athletes including a 12­lead electrocardiogram (ECG) is recommended by numerous international bodies. Current athlete ECG interpretation guidelines recommend the Bazett method to correct the QT interval (QTc). OBJECTIVE: This study sought to investigate normative QTc changes by age using athlete screening ECGs and different QT correction methods in a population of elite cricketers. METHODS: Initial cardiac screening ECGs from an existing database of elite Australian cricketers aged 14-35 years were examined. Average QT interval, QTcB (corrected QT-Bazett), QTcF (Fridericia), QTcH (Hodges), and heart rate (HR) were analyzed by age and sex. RESULTS: A total of 1310 athletes (66% male, 34% female) were included with mean age 19.1 years and mean heart rate 66.9 bpm (range 38-121 bpm). With increasing age, HR decreased and absolute QT increased. The pattern of QTc change with age differed depending on the method of correction: Bazett correction (QTcB) demonstrated a "dish-shaped" or broad U-shaped appearance; while Fridericia and Hodges corrections showed a linear increase in QTc from young to older age. The Bazett method had a stronger correlation of HR with QTc (R2 = 0.32) than either Fridericia (R2 = 0.0007) or Hodges (R2 = 0.009) methods. CONCLUSIONS: The Bazett method is not the most accurate QT correction in athletes, especially during adolescence. In elite cricketers, QTcB revealed a drop in QTc from adolescence to early adulthood due to mis-correction of the QT interval. The Fridericia method has the smoothest correction of HR and least QT variation by age and may be preferred for athlete screening.

Anteroposterior Versus Anterolateral Electrode Position for Direct Current Cardioversion of Atrial Fibrillation: A Meta-Analysis of Randomised Controlled Trials.

OBJECTIVE: Data regarding optimal electrode positioning for direct current cardioversion (DCCV) of atrial fibrillation (AF) has been inconsistent. This meta-analysis was conducted to systematically compare the efficacy of anteroposterior (AP) versus anterolateral (AL) electrode placement for DCCV of AF. METHODS: Electronic databases were searched for randomised controlled trials (RCTs) comparing AP versus AL electrode positioning in patients undergoing DCCV for AF. Primary endpoints were first-shock success and overall DCCV success. Subgroup analysis was performed by defibrillator waveform (monophasic versus biphasic). Meta-regression analyses were performed to assess for significant moderators. RESULTS: Twelve (12) RCTs, including a total of 2,046 patients, met inclusion criteria. Neither first-shock success (relative risk [RR] 0.92; 95% CI 0.79-1.07; p=0.28) nor overall DCCV success (RR 1.01; 95% CI 0.96-1.05; p=0.78) were significantly different with AP versus AL electrode positioning. The mean number of shocks (mean difference [MD] 0.3, 95% CI -0.4 to 0.9), energy level of first successful shock (MD 3 joules; 95% CI -20 to 27) and cumulative energy delivered (MD 39 joules; 95% CI -168 to 246) were similar in AP versus AL arms. In subgroup analysis of six RCTs using biphasic defibrillators, improvement in first-shock success (RR 0.85; 95% CI 0.69-1.03; p=0.10) and overall DCCV success (RR 0.97; 95% CI 0.93-1.01; p=0.09) with AL electrode positioning did not reach statistical significance. Meta-regression analyses identified older age, higher body mass index, and longer AF duration as significant moderators favouring AL electrode positioning. CONCLUSIONS: Pooled analysis of randomised data overall does not show a significant difference in efficacy between AP versus AL electrode positioning. Meta-regression and subgroup analyses suggest that, in contemporary practice with use of biphasic defibrillators, there may be a subset of AF patients in whom AL electrode positioning improves efficacy of DCCV.

Infanticide vs. inherited cardiac arrhythmias.

AIMS: In 2003, an Australian woman was convicted by a jury of smothering and killing her four children over a 10-year period. Each child died suddenly and unexpectedly during a sleep period, at ages ranging from 19 days to 18 months. In 2019 we were asked to investigate if a genetic cause could explain the children's deaths as part of an inquiry into the mother's convictions. METHODS AND RESULTS: Whole genomes or exomes of the mother and her four children were sequenced. Functional analysis of a novel CALM2 variant was performed by measuring Ca2+-binding affinity, interaction with calcium channels and channel function. We found two children had a novel calmodulin variant (CALM2 G114R) that was inherited maternally. Three genes (CALM1-3) encode identical calmodulin proteins. A variant in the corresponding residue of CALM3 (G114W) was recently reported in a child who died suddenly at age 4 and a sibling who suffered a cardiac arrest at age 5. We show that CALM2 G114R impairs calmodulin's ability to bind calcium and regulate two pivotal calcium channels (CaV1.2 and RyR2) involved in cardiac excitation contraction coupling. The deleterious effects of G114R are similar to those produced by G114W and N98S, which are considered arrhythmogenic and cause sudden cardiac death in children. CONCLUSION: A novel functional calmodulin variant (G114R) predicted to cause idiopathic ventricular fibrillation, catecholaminergic polymorphic ventricular tachycardia, or mild long QT syndrome was present in two children. A fatal arrhythmic event may have been triggered by their intercurrent infections. Thus, calmodulinopathy emerges as a reasonable explanation for a natural cause of their deaths.

Comparison between a 6­lead smartphone ECG and 12­lead ECG in athletes.

Athletes sometimes experience transient arrhythmias during intense exercise, which may be difficult to capture with traditional Holter monitors. New and highly portable technology, such as smartphone electrocardiogram (ECG) devices, may be useful in documenting and contribute to diagnosis of exercise-induced arrhythmias. There are little data available regarding the new Kardia 6 lead device (6L) and no data regarding its use in athletic populations. In this short communication, we present pilot data from 30 healthy athletes who underwent a 12­lead ECG and subsequent 6L reading. Our pilot data show relatively high levels of agreement for QTc and PR interval and QRS duration, with the 6L readings slightly but significantly shorter on average.

Epidemiology and clinical characteristics of atrial fibrillation in patients with inherited heart diseases.

BACKGROUND: The prevalence and clinical course of atrial fibrillation (AF) in hypertrophic cardiomyopathy (HCM) is well described, though less so for other inherited cardiomyopathies (familial dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, left ventricular noncompaction); and inherited arrhythmia syndromes (long QT syndrome, Brugada syndrome or catecholaminergic polymorphic ventricular tachycardia [CPVT]). We examined the frequency, clinical characteristics and AF-related management and outcomes amongst this patient population. METHODS: We retrospectively studied consecutive probands with inherited cardiomyopathy (n = 962) and inherited arrhythmia syndromes (n = 195) evaluated between 2002 and 2018. RESULTS: AF was observed in 5% to 31% of patients, with the highest frequency in HCM. Age of AF onset was 45.8 ± 21.9 years in the inherited arrhythmia syndromes compared with 53.3 ± 15.3 years in the inherited cardiomyopathies, with four CPVT patients developing AF at a median age of 20 years. Overall, 11% of patients with AF had a transient ischemic attack or stroke of which a total of 80% were anticoagulated; with 48% of events occurring at a CHA2 DS2 -VASc < 2. Amongst sarcomere-positive HCM, AF was independently associated with age (odds ratio [OR], 1.05; 95% confidence interval [CI], 1.02-1.08; P = .0014), left atrial area (OR, 1.11; 95% CI, 1.05-1.17; P = .0005) and MYH7 variants (OR, 2.55; 95% CI, 1.16-5.61; P = .020). CONCLUSION: Up to one-third of inherited heart disease patients will develop AF. While common general population risk factors are key in patients with HCM, the genotype is independently associated with AF. Amongst inherited arrhythmia syndromes, AF is less common, though often occurs below the age of 50 years.

Insights into sudden cardiac death: exploring the potential relevance of non-diagnostic autopsy findings.

AIMS: Unexplained sudden cardiac death (SCD) may be attributable to cardiogenetic disease. Presence or absence of autopsy anomalies detected following premature sudden death direct appropriate clinical evaluation of at-risk relatives towards inherited cardiomyopathies or primary arrhythmia syndromes, respectively. We investigated the relevance of non-diagnostic pathological abnormalities of indeterminate causality (uncertain) such as myocardial hypertrophy, fibrosis, or inflammatory infiltrates to SCD. METHODS AND RESULTS: At-risk relatives of unexplained SCD cases aged 1-64 years without prior cardiac disease (n = 98) with either normal and negative (40%, true sudden arrhythmic death syndrome; SADS) or isolated non-diagnostic (60%, uncertain sudden unexplained death; SUD) cardiac histological autopsy findings at a central forensic pathology unit were referred to the regional unexplained SCD clinic for clinical cardiac phenotyping. Uncertain SUD were older than true SADS cases (31.8 years vs. 21.1 years, P < 0.001). A cardiogenetic diagnosis was established in 24 families (24.5%) following investigation of 346 referred relatives. The proportions of uncertain SUD and true SADS explained by familial cardiogenetic diagnoses were similar (20% vs. 31%, P = 0.34, respectively), with primary arrhythmia syndromes predominating. Unexplained SCD cases were more likely than matched non-cardiac premature death controls to demonstrate at least one uncertain autopsy finding (P < 0.001). CONCLUSION: Primary arrhythmia syndromes predominate as familial cardiogenetic diagnoses amongst both uncertain SUD and true SADS cases. Non-diagnostic or uncertain histological findings associate with SUD, though cannot be attributed a causative status. At-risk relatives of uncertain SUD cases should be evaluated for phenotypic evidence of both ion channel disorders and cardiomyopathies.

Next-generation sequencing using microfluidic PCR enrichment for molecular autopsy.

BACKGROUND: We aimed to determine the mutation yield and clinical applicability of "molecular autopsy" following sudden arrhythmic death syndrome (SADS) by validating and utilizing low-cost high-throughput technologies: Fluidigm Access Array PCR-enrichment with Illumina HiSeq 2000 next generation sequencing (NGS). METHODS: We validated and optimized the NGS platform with a subset of 46 patients by comparison with Sanger sequencing of coding exons of major arrhythmia risk-genes (KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2, RYR2). A combined large multi-ethnic international SADS cohort was sequenced utilizing the NGS platform to determine overall molecular yield; rare variants identified by NGS were subsequently reconfirmed by Sanger sequencing. RESULTS: The NGS platform demonstrated 100% sensitivity for pathogenic variants as well as 87.20% sensitivity and 99.99% specificity for all substitutions (optimization subset, n = 46). The positive predictive value (PPV) for NGS for rare substitutions was 16.0% (27 confirmed rare variants of 169 positive NGS calls in 151 additional cases). The overall molecular yield in 197 multi-ethnic SADS cases (mean age 22.6 ± 14.4 years, 68% male) was 5.1% (95% confidence interval 2.0-8.1%), representing 10 cases carrying pathogenic or likely pathogenic risk-mutations. CONCLUSIONS: Molecular autopsy with Fluidigm Access Array and Illumina HiSeq NGS utilizing a selected panel of LQTS/BrS and CPVT risk-genes offers moderate diagnostic yield, albeit requiring confirmatory Sanger-sequencing of mutational variants.

Assessment of ablation catheter contact on valve annulus: Implications on accessory pathway ablation.

BACKGROUND: Catheter-tissue contact force is an important factor influencing lesion size and efficacy and thereby potential for arrhythmia recurrence following accessory pathway (AP) radiofrequency ablation. We aim to evaluate adequacy and perception of catheter contact on the tricuspid and mitral annuli. METHODS: Data were collected from 42 patients undergoing catheter ablation. Operators were blinded to contact force information and reported perceived contact (poor, moderate, or good) while positioning the catheter at four tricuspid annular sites (12, 9, 6 and 4 o'clock positions; abbreviated as TA12, TA9, TA6 and TA4) and three mitral annular sites (3, 5 and 7 o'clock positions; abbreviated as MA3, MA5 and MA7) through long vascular sheaths. RESULTS: The highest and lowest mean contact forces were obtained at MA7 (13.3 ±â€¯1.7 g) and TA12 (3.6 g ±â€¯1.3 g) respectively. Mean contact force on tricuspid annulus (6.1 g ±â€¯0.9 g) was lower than mitral annulus (9.8 ±â€¯0.9 g) locations (p = 0.0036), with greater proportion of sites with <10 g contact force (81.7% vs 60.4%; p = 0.0075). Perceived contact had no impact on measured mean contact force for both mitral and tricuspid annular positions (p = 0.959 and 0.671 respectively). There was correlation of both impedance and atrial electrogram amplitude with contact force, though insufficient to be clinically applicable. CONCLUSION: A high proportion of annular catheter applications have low contact force despite being performed with long vascular sheaths in the hands of experienced operators. In addition, there was no impact of operator perceived contact force on actual measured contact force. This may carry implications for success of AP ablation.

Trends in outpatient anti-arrhythmic prescriptions for atrial fibrillation and left atrial ablation in Australia: 1997-2016.

BACKGROUND: An important aspect of atrial fibrillation (AF) management is the decision whether to adopt a rate or rhythm control strategy. Options for the latter include oral anti-arrhythmic drugs (AAD) or catheter ablation. AIM: To describe the trends in rhythm control for AF in Australia between 1997 and 2016. METHODS: We conducted a retrospective study using prospectively collected data between 1997 and 2016 from the Pharmaceutical Benefit Scheme and Medicare Benefit Schedule websites, which, respectively, contain information pertaining to public AAD prescriptions and rebatable AF ablation procedures performed in Australia. RESULTS: Sotalol and amiodarone remain the most commonly prescribed AAD in Australia, although their use is decreasing. Rates of catheter ablation for AF continue to rise annually with a 48-fold increase from 71 to 3480 since 1997. CONCLUSION: A rhythm control strategy is frequently utilised for AF management in Australia. Consistent with international guidelines which advocate safety over efficacy when choosing a rhythm control strategy, the prescriptions of amiodarone have been consistently decreasing since 2002, whereas sotalol and flecainide prescriptions have largely increased, with a peak in 2015. Catheter ablation per capita has burgeoned 36-fold.

Management of Atrial Fibrillation in the Athlete.

Atrial fibrillation (AF) is a recognised arrhythmic risk of endurance sports participation, predominantly affecting middle-aged men who are lifelong athletes. Affected athletes were historically included in the category of lone AF, although specific pathophysiological processes apply to this condition, referred to as exercise-related AF. Younger non-endurance athletes may also present with AF, particularly when associated with co-existing cardiomyopathy or arrhythmia syndrome. Management of exercise-related AF is largely based on evidence from randomised trials in non-athletes. Cornerstones of treatment are, thus, thromboembolic risk reduction and risk factor modification. Rhythm control is generally preferred over rate control due to frequent presentation with symptomatic AF during the paroxysmal phase. Many therapies specific to athletes are based on expert consensus alongside observational data in athletic populations. These include: recommendations to detrain; treatment of symptomatic oesophageal reflux; and preferential use of anticholinergic antidysrhythmic agents to address the predominance of "vagal" AF in athletes. Ongoing research involving cardiac ion channel remodelling and systemic inflammation as mediators of AF genesis may provide future novel therapeutic targets for exercise-related AF. Ablative therapy shows promise in the athletic population with AF, although evidence remains limited. International consensus guidance for disqualification from competitive sports exists to guide medical management alongside athletes' preferences to continue to participate. This review focusses on isolated exercise-related AF and reviews the evidence supporting postulated management recommendations of this unique patient population.

Results of a nationally implemented de novo cardiac screening programme in elite rugby players in England.

BACKGROUND/AIM: Screening of young competitive athletes remains a contentious issue. In 2010, a nationwide cardiac screening for all elite rugby players was introduced in England. This provided a unique opportunity to prospectively assess the feasibility and cost-effectiveness of a de novo, ECG-based cardiac screening programme. METHODS: Between 2010 and 2012, 1191 rugby players aged ≥14 years underwent cardiac screening with a health questionnaire, 12-lead ECG and a consultation with a cardiologist. The players with concerning findings on initial evaluation were offered on-site transthoracic echocardiogram (TTE). Athletes were referred for further investigations as deemed necessary. The overall cost of the screening programme was estimated. RESULTS: After initial evaluation, 9.7% of athletes underwent on-site TTE; 8.2% underwent on-site TTE due to ECG anomalies and 1.4% underwent on-site TTE due to concerns on the questionnaire. After TTE, only 2.9% of the total cohort was referred for further evaluation. Two players were diagnosed with potentially serious conditions; one with Wolff-Parkinson-White, who resumed competition after catheter ablation, and one with hypertrophic cardiomyopathy, who withdrew from competition. During a mean follow-up of 52.8±5.5 months, none of the players who were reassured experienced any adverse cardiac events. The total cost of the screening programme was £59 875, which averaged to a cost of £50 per player or £29 938 per condition identified. Application of refined ECG criteria would reduce the ECG false-positive rate to 4.9%. CONCLUSIONS: Preparticipation cardiac screening with 12-lead ECG is feasible. Refinement of the ECG criteria, the use of on-site TTE and expert setting can minimise the burden of unnecessary investigations and reduce costs.

Electroanatomic Mapping and Transoesophageal Echocardiography for near Zero Fluoroscopy during Complex Left Atrial Ablation.

BACKGROUND: We evaluated Carto 3, transoesophageal echocardiography (TOE) and contact force (CF) sensing catheter in atrial fibrillation (AF) ablation. METHODS: Unselected consecutive ablations performed under general anaesthesia (GA) were studied with modified protocol (cases, n=11) and compared to retrospective consecutive controls (n=10). Patent foramen ovale (PFO) or single transseptal puncture enabled left atrial (LA) access; ablation strategy was stepwise approach. Modified protocol utilised right atrial (RA) electrograms, CF and TOE to localise SmartTouch and create RA and CS electroanatomic map (EAM) without fluoroscopy. Transseptal puncture was performed with fluoroscopy in absence of PFO. Fluoroless pulmonary vein and LA EAM was created using TOE to locate circular-mapping catheter. RESULTS: Mean age of cases was 57±11 years with 64% male compared with 60±11 (70% male) for controls. Patent foramen ovale was identified in four cases (36%) and two controls (20%). No early complications occurred. Shorter fluoroscopy time (median 36 vs 390seconds; p=0.038) and trend to lower radiation dose (median 17 vs 165 cGym2; p=0.053) was seen in cases, with no increase in total procedure time (p=0.438). CONCLUSIONS: General anaesthesia, TOE and CF mapping catheters facilitate minimised fluoroscopy for catheter ablation of LA arrhythmias. Zero fluoroscopy is possible in a majority of cases with PFO.

Should axis deviation or atrial enlargement be categorised as abnormal in young athletes? The athlete's electrocardiogram: time for re-appraisal of markers of pathology.

AIMS: The 2010 European Society of Cardiology (ESC) guidelines for electrocardiogram (ECG) interpretation in athletes are associated with a relatively high false positive rate and warrant modification to improve the specificity without compromising sensitivity. The aim of this study was to investigate whether non-specific anomalies such as axis deviation and atrial enlargement in isolation require further assessment in highly trained young athletes. METHOD AND RESULTS: Between 2003 and 2011, 2533 athletes aged 14-35 years were investigated with 12-lead ECG and echocardiography. Electrocardiograms were analysed for non-training-related (Group 2) changes according to the 2010 ESC guidelines. Results were compared with 9997 asymptomatic controls. Of the 2533 athletes, 329 (13%) showed Group 2 ECG changes. Isolated axis deviation and isolated atrial enlargement comprised 42.6% of all Group 2 changes. Athletes revealed a slightly higher prevalence of these anomalies compared with controls (5.5 vs. 4.4%; P = 0.023). Echocardiographic evaluation of athletes and controls with isolated axis deviation or atrial enlargement (n = 579) failed to identify any major structural or functional abnormalities. Exclusion of axis deviation or atrial enlargement reduced the false positive rate from 13 to 7.5% and improved specificity from 90 to 94% with a minimal reduction in sensitivity (91-89.5%). CONCLUSION: Isolated axis deviation and atrial enlargement comprise a high burden of Group 2 changes in athletes and do not predict underlying structural cardiac disease. Exclusion of these anomalies from current ESC guidelines would improve specificity and cost-effectiveness of pre-participation screening with ECG.

Clinical significance of electrocardiographic right ventricular hypertrophy in athletes: comparison with arrhythmogenic right ventricular cardiomyopathy and pulmonary hypertension.

AIMS: Pre-participation cardiovascular screening of young athletes may prevent sports-related sudden cardiac deaths. Recognition of physiological electrocardiography (ECG) changes in healthy athletes has improved the specificity of screening while maintaining sensitivity for disease. The study objective was to determine the clinical significance of electrocardiographic right ventricular hypertrophy (RVH) in athletes. METHODS AND RESULTS: Between 2010 and 2012, 868 subjects aged 14-35 years (68.8% male) were assessed using ECG and echocardiography (athletes; n = 627, sedentary controls; n = 241). Results were compared against patients with established right ventricular (RV) pathology (arrhythmogenic right ventricular cardiomyopathy, n = 68; pulmonary hypertension, n = 30). Sokolow-Lyon RVH (R[V1]+S[V5orV6] > 1.05 mV) was more prevalent in athletes than controls (11.8 vs. 6.2%, P = 0.017), although RV wall thickness (RVWT) was similar (4.0 ± 1.0 vs. 3.9 ± 0.9 mm, P = 0.18). Athletes exhibiting electrocardiographic RVH were predominantly male (95.9%), and demonstrated similar RV dimensions and function to athletes with normal electrocardiograms (RVWT; 4.0 ± 1.1 vs. 4.0 ± 0.9 mm, P = 0.95, RV basal dimension; 42.7 ± 5.2 vs. 42.1 ± 5.9 mm, P = 0.43, RV fractional area change; 40.6 ± 7.6 vs. 42.2 ± 8.1%, P = 0.14). Sensitivity and specificity of Sokolow-Lyon RVH for echocardiographic RVH (>5 mm) were 14.3 and 88.2%, respectively. Further evaluation including cardiac magnetic resonance imaging did not diagnose right ventricular pathology in any athlete. None of the cardiomyopathic or pulmonary hypertensive patients exhibited voltage RVH without additional ECG abnormalities. CONCLUSION: Electrocardiographic voltage criteria for RVH are frequently fulfilled in healthy athletes without underlying RV pathology, and should not prompt further evaluation if observed in isolation. Recognition of this phenomenon should reduce the burden of investigations after pre-participation ECG screening without compromising sensitivity for disease.

Unexplained sudden death, focussing on genetics and family phenotyping.

PURPOSE OF REVIEW: Unexplained sudden death and the sudden arrhythmic death syndrome (SADS) affect a small but significant proportion of young and apparently healthy individuals. This review revisits the causes underlying such deaths and the investigational strategies that identify surviving family who may be at risk. RECENT FINDINGS: Recent epidemiological data is available from case series or government records. The yield from familial cardiological evaluation for inherited conditions has been supported by additional small series. The greatest advance has come with molecular autopsy studies, which have utilized various methodologies and candidate genes to investigate SADS cases and their families. SUMMARY: The latest research replicates and extends the existing knowledge regarding epidemiology and familial evaluation of SADS, whilst genetic studies support a role for the molecular autopsy.

Longitudinal assessment of structural phenotype in Brugada syndrome using cardiac magnetic resonance imaging.

Background: Despite historically being considered a channelopathy, subtle structural changes have been reported in Brugada syndrome (BrS) on histopathology and cardiac magnetic resonance (CMR) imaging. It is not known if these structural changes progress over time. Objective: The study sought to assess if structural changes in BrS evolve over time with serial CMR assessment and to investigate the utility of parametric mapping techniques to identify diffuse fibrosis in BrS. Methods: Patients with a diagnosis of BrS based on international guidelines and normal CMR at least 3 years prior to the study period were invited to undergo repeat CMR. CMR images were analyzed de novo and compared at baseline and follow-up. Results: Eighteen patients with BrS (72% men; mean age at follow-up 47.4 ± 8.9 years) underwent serial CMR with an average of 5.0 ± 1.7 years between scans. No patients had late gadolinium enhancement (LGE) on baseline CMR, but 4 (22%) developed LGE on follow-up, typically localized to the right ventricular (RV) side of the basal septum. RV end-systolic volume increased over time (P = .04) and was associated with a trend toward reduction in RV ejection fraction (P = .07). Four patients showed a reduction in RV ejection fraction >10%. There was no evidence of diffuse myocardial fibrosis observed on parametric mapping. Conclusions: Structural changes may evolve over time with development of focal fibrosis, evidenced by LGE on CMR in a significant proportion of patients with BrS. These findings have implications for our understanding of the pathological substrate in BrS and the longitudinal evaluation of patients with BrS.