Genetic Variant Score and Arrhythmogenic Right Ventricular Cardiomyopathy Phenotype in Plakophilin-2 Mutation Carriers.

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.

QT correction using Bazett's formula remains preferable in long QT syndrome type 1 and 2.

BACKGROUND: The heart rate (HR) corrected QT interval (QTc) is crucial for diagnosis and risk stratification in the long QT syndrome (LQTS). Although its use has been questioned in some contexts, Bazett's formula has been applied in most diagnostic and prognostic studies in LQTS patients. However, studies on which formula eliminates the inverse relation between QT and HR are lacking in LQTS patients. We therefore determined which QT correction formula is most appropriate in LQTS patients including the effect of beta blocker therapy and an evaluation of the agreement of the formulae when applying specific QTc limits for diagnostic and prognostic purposes. METHODS: Automated measurements from routine 12-lead ECGs from 200 genetically confirmed LQTS patients from two Swedish regions were included (167 LQT1, 33 LQT2). QT correction was performed using the Bazett, Framingham, Fridericia, and Hodges formulae. Linear regression was used to compare the formulae in all patients, and before and after the initiation of beta blocking therapy in a subgroup (n = 44). Concordance analysis was performed for QTc ≥ 480 ms (diagnosis) and ≥500 ms (prognosis). RESULTS: The median age was 32 years (range 0.1-78), 123 (62%) were female and 52 (26%) were children ≤16 years. Bazett's formula was the only method resulting in a QTc without relation with HR. Initiation of beta blocking therapy did not alter the result. Concordance analyses showed clinically significant differences (Cohen's kappa 0.629-0.469) for diagnosis and prognosis in individual patients. CONCLUSION: Bazett's formula remains preferable for diagnosis and prognosis in LQT1 and 2 patients.

Pregnancies, ventricular arrhythmias, and substrate progression in women with arrhythmogenic right ventricular cardiomyopathy in the Nordic ARVC Registry.

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.

Absence of ECG Task Force Criteria does not rule out structural changes in genotype positive ARVC patients.

AIMS: In Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC), electrophysiological pathology has been claimed to precede morphological and functional pathology. Accordingly, an ECG without ARVC markers should be rare in ARVC patients with pathology identified by cardiac imaging. We quantified the prevalence of ARVC patients with evidence of structural disease, yet without ECG Task Force Criteria (TFC). METHODS AND RESULTS: We included 182 probands and family members with ARVC-associated mutations (40 ± 17 years, 50% women, 73% PKP2 mutations) from the Nordic ARVC Registry in a cross-sectional analysis. For echocardiography and cardiac MR (CMR), we differentiated between "abnormalities" and TFC. "Abnormalities" were defined as RV functional or structural measures outside TFC reference values, without combinations required to fulfill TFC. ECG TFC were used as defined, as these are not composite parameters. We found that only 4% of patients with ARVC fulfilled echocardiographic TFC without any ECG TFC. However, importantly, 38% of patients had imaging abnormalities without any ECG TFC. These results were supported by CMR data from a subset of 51 patients: 16% fulfilled CMR TFC without fulfilling ECG TFC, while 24% had CMR abnormalities without any ECG TFC. In a multivariate analysis, echocardiographic TFC were associated with arrhythmic events. CONCLUSION: More than one third of ARVC genotype positive patients had subtle imaging abnormalities without fulfilling ECG TFC. Although most patients will have both imaging and ECG abnormalities, structural abnormalities in ARVC genotype positive patients cannot be ruled out by the absence of ECG TFC.

Incidence, Predictors, and Success of Ventricular Tachycardia Catheter Ablation in Arrhythmogenic Right Ventricular Cardiomyopathy (from the Nordic ARVC Registry).

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.

Outcome after heart-lung or lung transplantation in patients with Eisenmenger syndrome.

OBJECTIVE: The optimal timing for transplantation is unclear in patients with Eisenmenger syndrome (ES). We investigated post-transplantation survival and transplantation-specific morbidity after heart-lung transplantation (HLTx) or lung transplantation (LTx) in a cohort of Nordic patients with ES to aid decision-making for scheduling transplantation. METHODS: We performed a retrospective, descriptive, population-based study of patients with ES who underwent transplantation from 1985 to 2012. RESULTS: Among 714 patients with ES in the Nordic region, 63 (9%) underwent transplantation. The median age at transplantation was 31.9 (IQR 21.1-42.3) years. Within 30 days after transplantation, seven patients (11%) died. The median survival was 12.0 (95% CI 7.6 to 16.4) years and the overall 1-year, 5-year, 10-year and 15-year survival rates were 84.1%, 69.7%, 55.8% and 40.6%, respectively. For patients alive 1 year post-transplantation, the median conditional survival was 14.8 years (95% CI 8.0 to 21.8), with 5-year, 10-year and 15-year survival rates of 83.3%, 67.2% and 50.0%, respectively. There was no difference in median survival after HLTx (n=57) and LTx (n=6) (14.9 vs 10.6 years, p=0.718). Median cardiac allograft vasculopathy, bronchiolitis obliterans syndrome and dialysis/kidney transplantation-free survival rates were 11.2 (95% CI 7.8 to 14.6), 6.9 (95% CI 2.6 to 11.1) and 11.2 (95% CI 8.8 to 13.7) years, respectively. The leading causes of death after the perioperative period were infection (36.7%), bronchiolitis obliterans syndrome (23.3%) and heart failure (13.3%). CONCLUSIONS: This study shows that satisfactory post-transplantation survival, comparable with contemporary HTx and LTx data, without severe comorbidities such as cardiac allograft vasculopathy, bronchiolitis obliterans syndrome and dialysis, is achievable in patients with ES, with a conditional survival of nearly 15 years.

Atrial fibrillation as a clinical characteristic of arrhythmogenic right ventricular cardiomyopathy: Experience from the Nordic ARVC Registry.

BACKGROUND: Recent studies in arrhythmogenic right ventricular cardiomyopathy (ARVC) patients have drawn attention 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 [interquartile 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 family member (1%), p < 0.001. The median age at AF onset was 51 (IQR 38-58) years. The prevalence of AF was related to the ARVC diagnostic score: it significantly increased starting with 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 (Somer's d value is 0.074, p < 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.

Development of heart failure in young patients with congenital heart disease: a nation-wide cohort study.

Objective: Heart failure (HF) is a common cause of hospitalisation and death in adults with congenital heart disease (CHD). However, the risk of HF in young patients with CHD has not been determined. Methods: By linkage of national patient registers in Sweden, we identified 21 982 patients with CHD born between 1970 and 1993, and compared these with 10 controls per case. Follow-up data were collected from birth until 2011 or death. Results: Over a mean follow-up of 26.6 years in patients with CHD and 28.5 years in controls, 729 (3.3%) and 75 (0.03%) developed HF, respectively. The cumulative incidence of HF in all CHD was 6.5% and in complex CHD 14.8% up to age 42 years. Thus, one patient in 15 with CHD runs the risk of developing HF before age 42 years, a risk that is 105.7 times higher (95 % CI 83.2 to 134.8) compared with controls. For patients with complex CHD (such as conotruncal defects, univentricular hearts, endocardial cushion defects), one in seven will develop HF, a HR of 401.5; 95% CI 298 to 601 as compared with controls. The cumulative probability of death in patients with CHD, after HF diagnosis, was 63.4% (95% CI 57.5 to 69.3). Conclusions: An extremely high risk of developing HF (more than 100-fold) was found in patients with CHD, compared with matched controls, up to the age of 42 years. Patients with complex congenital heart malformations carried the highest risk and have to be considered as the main risk group for developing HF.

Primary Prevention of Sudden Cardiac Death With Implantable Cardioverter-Defibrillator Therapy in Patients With Arrhythmogenic Right Ventricular Cardiomyopathy.

Implantable cardioverter-defibrillator (ICD) therapy remains a corner stone of sudden cardiac death (SCD) prevention in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). We aimed to assess predictors of appropriate ICD therapies in the Scandinavian cohort of ARVC patients who received ICD for primary prevention of SCD. Study group comprised of 79 definite ARVC patients by 2010 Task Force criteria (60% male, age at ICD implant 39 ± 14 years) who were enrolled in the Nordic ARVC Registry and received an ICD for primary SCD prevention. The primary end point of appropriate ICD shock or death from any cause was assessed and compared with 137 definite ARVC patients who received ICD for secondary SCD prevention (74% male, age at ICD implant 42 ± 15 years). In the study group, 38% were ≤35 years of age at baseline, 25% had nonsustained ventricular tachycardia, and 29% had syncope at baseline. Major repolarization abnormality (hazard ratio = 4.00, 95% confidence interval 1.30 to 12.30, p = 0.015) and age ≤35 years (hazard ratio = 4.21, 95% confidence interval 1.49 to 11.85, p = 0.001) independently predicted the primary end point. The outcome did not differ between the primary prevention patients with either of these risk factors and the secondary prevention cohort (2% to 4% annual event rate) whereas patients without risk factors did not have any appropriate ICD shocks during follow-up. In conclusion, young age at ARVC diagnosis and major repolarization abnormality independently predict ICD shocks or death in the primary prevention ICD recipients and associated with the event rate similar to the one observed in the secondary prevention cohort. Our data indicate the benefit of ICD for primary prevention in patients with any of these risk factors.

Differential Effects of Levosimendan and Dobutamine on Glomerular Filtration Rate in Patients With Heart Failure and Renal Impairment:A Randomized Double-Blind Controlled Trial.

Background The management of the cardiorenal syndrome in advanced heart failure is challenging, and the role of inotropic drugs has not been fully defined. Our aim was to compare the renal effects of levosimendan versus dobutamine in patients with heart failure and renal impairment. Methods and Results In a randomized double-blind study, we assigned patients with chronic heart failure (left ventricular ejection fraction <40%) and impaired renal function (glomerular filtration rate <80 mL/min per 1.73 m2) to receive either levosimendan (loading dose 12 µg/kg+0.1 µg/kg per minute) or dobutamine (7.5  µg/kg per minute) for 75 minutes. A pulmonary artery catheter was used for measurements of systemic hemodynamics, and a renal vein catheter was used to measure renal plasma flow by the infusion clearance technique for PAH (para-aminohippurate) corrected by renal extraction of PAH . Filtration fraction was measured by renal extraction of chromium ethylenediamine tetraacetic acid. A total of 32 patients completed the study. Following treatment, the levosimendan and dobutamine groups displayed similar increases in renal blood flow (22% and 26%, respectively) with no significant differences between groups. Glomerular filtration rate increased by 22% in the levosimendan group but remained unchanged in the dobutamine group ( P=0.012). Filtration fraction was not affected by levosimendan but decreased by 17% with dobutamine ( P=0.045). Conclusions In patients with chronic heart failure and renal impairment, levosimendan increases glomerular filtration rate to a greater extent than dobutamine and thus may be the preferred inotropic agent for treating patients with the cardiorenal syndrome. Clinical Trial Registration URL: https://www.clinicaltrials.gov . Unique identifier: NCT 02133105.

Heart transplantation in arrhythmogenic right ventricular cardiomyopathy - Experience from the Nordic ARVC Registry.

OBJECTIVE: There is a paucity of data on heart transplantation (HTx) in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC), and specific recommendations on indications for listing ARVC patients for HTx are lacking. In order to delineate features pertinent to HTx assessment, we explored the pre-HTx characteristics and clinical history in a cohort of ARVC patients who received heart transplants. METHODS: Data from 31 ARVC/HTx patients enrolled in the Nordic ARVC Registry, transplanted between 1988 and 2014 at a median age of 46years (14-65), were compared with data from 152 non-transplanted probands with Definite ARVC according to 2010 Task Force Criteria from the same registry. RESULTS: The HTx patients were younger at presentation, median 31 vs. 38years (p=0.001). There was no difference in arrhythmia-related events. The indication for HTx was heart failure in 28 patients (90%) and ventricular arrhythmias in 3 patients (10%). During median follow-up of 4.9years (0.04-28), there was one early death and two late deaths. Survival was 91% at 5years after HTx. Age at first symptoms under 35years independently predicted HTx in our cohort (OR=7.59, 95% CI 2.69-21.39, p<0.001). CONCLUSION: HTx in patients with ARVC is performed predominantly due to heart failure. This suggests that current 2016 International Society for Heart and Lung Transplantation heart transplant listing recommendations for other cardiomyopathies could be applicable in many cases when taking into account the haemodynamic consequences of right ventricular failure in conjunction with ventricular arrhythmia.

Atrial Fibrillation Burden in Young Patients With Congenital Heart Disease.

BACKGROUND: Patients with congenital heart disease (CHD) are assumed to be vulnerable to atrial fibrillation (AF) as a result of residual shunts, anomalous vessel anatomy, progressive valvulopathy, hypertension, and atrial scars from previous heart surgery. However, the risk of developing AF and the complications associated with AF in children and young adults with CHD have not been compared with those in control subjects. METHODS: Data from the Swedish Patient and Cause of Death registers were used to identify all patients with a diagnosis of CHD who were born from 1970 to 1993. Each patient with CHD was matched by birth year, sex, and county with 10 control subjects from the Total Population Register in Sweden. Follow-up data were collected until 2011. RESULTS: Among 21 982 patients (51.6% men) with CHD and 219 816 matched control subjects, 654 and 328 developed AF, respectively. The mean follow-up was 27 years. The risk of developing AF was 21.99 times higher (95% confidence interval, 19.26-25.12) in patients with CHD than control subjects. According to a hierarchical CHD classification, patients with conotruncal defects had the highest risk (hazard ratio, 84.27; 95% confidence interval, 56.86-124.89). At the age of 42 years, 8.3% of all patients with CHD had a recorded diagnosis of AF. Heart failure was the quantitatively most important complication in patients with CHD and AF, with a 10.7% (70 of 654) recorded diagnosis of heart failure. CONCLUSIONS: The risk of AF in children and young adults with CHD was 22 times higher than that in matched control subjects. Up to the age of 42 years, 1 of 12 patients with CHD had developed AF, and 1 of 10 patients with CHD with AF had developed heart failure. The patient groups with the most complex congenital defects carried the greatest risk of AF and could be considered for targeted monitoring.

Massive parallel sequencing questions the pathogenic role of missense variants in dilated cardiomyopathy.

BACKGROUND: Germline genetic variants are an important cause of dilated cardiomyopathy (DCM). However, recent sequencing studies have revealed rare variants in DCM-associated genes also in individuals without known heart disease. In this study, we investigate variant prevalence and genotype-phenotype correlations in Swedish DCM patients, and compare their genetic variants to those detected in reference cohorts. METHODS AND RESULTS: We sequenced the coding regions of 41 DCM-associated genes in 176 unrelated patients with idiopathic DCM and found 102 protein-altering variants with an allele frequency of <0.04% in reference cohorts; the majority were missense variants not previously described in DCM. Fifty-five (31%) patients had one variant, and 24 (14%) patients had two or more variants in the analysed genes. Detection of genetic variants in any gene, and in LMNA, MYH7 or TTN alone, was associated with early onset disease and reduced transplant-free survival. As expected, nonsense and frameshift variants were more common in DCM patients than in healthy individuals of the reference cohort 1000 Genomes Europeans. Surprisingly however, the prevalence, conservation and pathogenicity scores, and localization of missense variants were similar in DCM patients and healthy reference individuals. CONCLUSION: To our knowledge, this is the first study to identify correlations between genotype and prognosis when sequencing a large number of genes in unselected DCM patients. The similar distribution of missense variants in DCM patients and healthy reference individuals questions the pathogenic role of many variants, and suggests that results from genetic testing of DCM patients should be interpreted with caution.

Management of patients with Arrhythmogenic Right Ventricular Cardiomyopathy in the Nordic countries.

OBJECTIVES: Diagnostics of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) are complex, and based on the 2010 Task Force document including different diagnostic modalities. However, recommendations for clinical management and follow-up of patients with ARVC and their relatives are sparse. This paper aims to give a practical overview of management strategies, risk stratification, and selection of appropriate therapies for patients with ARVC and their family members. DESIGN: This paper summarizes follow-up and treatment strategies in ARVC patients in the Nordic countries. The author group represents cardiologists who are actively involved in the Nordic ARVC Registry which was established in 2009, and contains prospectively collected clinical data from more than 590 ARVC patients from Denmark, Norway, Sweden, and Finland. RESULTS: Different approaches of management and follow-up are required in patients with definite ARVC and in genetic-mutation-positive family members. Furthermore, ARVC patients with and without implantable cardioverter defibrillators (ICDs) require different follow-up strategies. CONCLUSION: Careful follow-up is required in patients with ARVC diagnosis to evaluate the need of anti-arrhythmic therapy and ICD implantation. Mutation-positive family members should be followed regularly for detection of early disease and risk stratification of ventricular arrhythmias.

The diagnostic performance of imaging methods in ARVC using the 2010 Task Force criteria.

AIMS: This study evaluates the agreement between echocardiographic and cardiac magnetic resonance (CMR) imaging data, and the impact a discrepancy between the two may have on the clinical diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC). METHODS AND RESULTS: From the Nordic ARVC Registry, 102 patients with definite ARVC who had undergone both echocardiography and CMR were included (median age 42 ± 16 years, 36% female, 78% probands). Patients were divided into two groups according to CMR-positive or -negative criteria, and the echocardiographic data were compared between the two. There were 72 CMR-positive patients. They had significantly larger RV dimensions and lower fractional area change on echocardiography compared with CMR-negative patients; parasternal long-axis right ventricular outflow tract (RVOT) 37 ± 7 vs. 32 ± 5 mm, parasternal short-axis RVOT 38 ± 7 vs. 32 ± 6 mm, fractional area shortening 31 ± 9 vs. 39 ± 9% (P < 0.003 for all). Only 36 (50%) of the CMR-positive patients fulfilled ARVC criteria by echocardiography, hence the diagnostic performance was low; sensitivity 50% and specificity 70%, positive predictive value 80% and negative predictive value 37%. Individuals with regional wall abnormalities on CMR were more likely to have ventricular arrhythmias (77 vs. 57%, P = 0.047). CONCLUSION: A significant proportion of patients with imaging-positive ARVC by CMR did not fulfil echocardiographic ARVC 2010 criteria. These findings confirm that echocardiographic evaluation of subtle structural changes in the right ventricle may be unreliable, and the diagnostic performance of CMR compared with echocardiography should be reflected in the guidelines.

Cardiac autonomic function in adolescents operated by arterial switch surgery.

BACKGROUND: Children with transposition of the great arteries, in whom an arterial switch operation (ASO) is performed, have been shown to have an increased incidence of sudden death, which may be due to cardiac autonomic imbalance and repolarisation instability. We hypothesised that i) cardiac norepinephrine (NE) kinetics and ii) arterial baroreflex sensitivity (BRS), reflecting sympathetic activity and vagal function respectively, are altered in this group. METHODS AND RESULTS: 17 children (15.8 ± 1.5 years of age) with ASO-surgery in the neonatal period were studied. 17 had cardiac BRS assessed by spontaneous fluctuations of systolic blood pressure and RR-interval, and repolarisation was measured as QT variability index. Matched healthy subjects were controls. Cardiac vagal function and repolarisation pattern were unchanged following ASO-surgery. At cardiac catheterisation, we infused tritiated NE in 8 of these children to examine total body and cardiac sympathetic function at baseline and following 5 min of adenosine infusion to induce reflex sympathetic activation. Blood was sampled simultaneously from the aorta and coronary sinus. Cardiac fractional extraction of ([3H])NE was substantially lower in operated children, being 56 ± 10 vs. 82 ± 9% (p=0.0001). Following i.v. adenosine in the operated group, NE total body spillover doubled vs. baseline (p<0.002) and the coronary venous-arterial concentration gradient of ([3H])dihydroxyphenylglycol increased 4-fold (p=0.04). CONCLUSIONS: Arterial switch operation performed neonatally appears to leave cardiac vagal function intact and, although cardiac sympathetic activation in response to adenosine occurs, cardiac neuronal NE reuptake is impaired. This may be pro-arrhythmic by reducing removal capacity of NE from the cardiac synaptic cleft.

Vectorcardiography analysis of the repolarization response to pharmacologically induced autonomic nervous system modulation in healthy subjects.

Autonomic nervous system activity is essential for regulation of ventricular repolarization (VR) and plays an important role in several arrhythmogenic conditions. This study in 31 healthy adult subjects (16 men, 15 women) evaluated the VR response to pharmacologically modulated autonomic nervous system activity applying vectorcardiography (VCG) analysis. During continuous VCG recording, 0.01-0.1 µg·kg(-1)·min(-1) isoprenaline (Iso) was infused at an increasing flow rate until three targeted heart rates (HR) were reached. After Iso washout, one intravenous bolus of 0.04 mg/kg atropine was given followed by an intravenous bolus of 0.2 mg/kg propranolol. A 5-min steady-state VCG recording was analyzed for each of the seven phases (including baseline 1 and 2). Furthermore, during the first 4 min following atropine, six periods of 10-s VCG were selected for subanalysis to evaluate the time course of change. The analysis included QRS, QT, and T-peak to T-end intervals, measures of the QRS and T vectors and their relation, as well as T-loop morphology parameters. By increasing HR, Iso infusion decreased HR dependent parameters reflecting total heterogeneity of VR (T area) and action potential morphology (ventricular gradient). In contrast, Iso prolonged QT HR corrected according to Bazett and increased the T-peak to T-end-to-QT ratio to levels observed in arrhythmogenic conditions. HR acceleration after atropine was accompanied by a transient paradoxical QT prolongation and delayed HR adaptation of T area and ventricular gradient. In addition to the expected HR adaptation, the VR response to ß-adrenoceptor stimulation with Iso and to muscarinic receptor blockade with atropine thus included alterations previously observed in congenital and acquired long QT syndromes, demonstrating substantial overlap between physiological and pathophysiological electrophysiology.

First two decades of paediatric heart transplantation in Sweden - outcome of listing and post-transplant results.

AIMS: To evaluate outcome in the first generation of children with end-stage heart disease to whom heart transplantation was available. METHODS: Retrospective review of all 135 Swedish children <18 years old listed for heart transplantation 1989-2009, followed to December 31, 2009, including 74 (55%) with cardiomyopathy and 61 (45%) with congenital heart disease; 34 (25%) were infants (<1 year). Cumulative risk of requiring heart transplantation was 1:17,300 (11 patients who improved were omitted from outcome analysis). RESULTS: Waiting-list mortality was 31% (44% in infants). Median waiting time in 82 transplanted patients was 57 days (0-585 days). Post-transplant follow-up time was median 5.9 years (0.03-20.1 years), and actuarial survival was 92% at 1 year, 82% at 5 years, 76% at 10 years and 58% at 15 years. Survival after listing was 64% at 1 year, 58% at 5 years, 52% at 10 years and 40% at 15 years. Post-transplant complications included rejections (34%), malignancies (12%), renal failure (8%), coronary artery vasculopathy (6%) and re-transplantation (5%). Among 64 survivors, 84% were free of complications affecting prognosis. CONCLUSION: High waiting-list mortality and post-transplant attrition precluded 60% of this pioneer population from reaching adulthood. Functional status in survivors is generally good.