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Aim To compare risk algorithms (HCMRisk-Kids, ECG Risk-score) in hypertrophic cardiomyopathy (HCM) without syndrome association (ns-HCM) and with Noonan-like syndromes (RAS-HCM). Methods A national paediatric HCM cohort (n = 151), presenting = 6% at diagnosis had C-statistic of 0.69 for predicting SCD/CA during first 5 years of follow-up and positive predictive value (PPV) of 22%. After 7 years of age (HCMRisk-Kids7plus), C-statistic was 0.76. ECG Risk-score >= 6 at diagnosis had C-statistic 0.87 and PPV of 31%. Independent risk factors for SCD/CA were HCMRisk-Kids7plus score (p = 0.005) and ECG risk-score (p < 0.001), whereas early beta-blocker dose (p = 0.001) and myectomy (p = 0.004) reduced risk. The sum of HCMRisk-Kids7yplus and ECG Risk-score7yplus >= 14 best predicted SCD/CA within 5 years in ns-HCM with C-statistic of 0.90 [0.83-0.96], sensitivity 100% and PPV 38%. Conclusion Combining the ECG Risk-score with HCMRisk-Kids improves risk stratification in ns-HCM and shows promise in RAS-HCM. Funding Agencies|Swedish Heart-and Lung FoundationSwedish Heart-Lung Foundation [20080510]; Swedish government; ALF agreement [ALFgbg-544981]; Region Ostergotland (ALF); Strategic Research Area in Forensic Science; FORSS (Medical Research Council of Southeast Sweden)

An ECG risk-score has been described that predicts high risk of subsequent cardiac arrest in young patients with hypertrophic cardiomyopathy (HCM). Myocardial fibrosis measured by cardiac magnetic resonance (CMR) late gadolinium enhancement (LGE) also affects prognosis. We assessed whether an ECG risk-score could be used as an indicator of myocardial fibrosis or perfusion deficit on CMR in HCM. In total 42 individuals (7–31 years); 26 HCM patients, seven genotype-positive, phenotype-negative individuals at risk of HCM (first-degree relatives) and nine healthy volunteers, underwent CMR to identify, and grade extent of, myocardial fibrosis and perfusion defect. 12-lead ECG was used for calculating the ECG risk-score (grading 0–14p). High-risk ECG (risk-score > 5p) occurred only in the HCM group (9/26), and the proportion was significantly higher vs mutation carriers combined with healthy volunteers (0/16, p = 0.008). Extent of LGE correlated to the ECG-score (R2 = 0.47, p = 0.001) in sarcomeric mutations. In low-risk ECG-score patients (0–2p), median percent of myocardium showing LGE (LGE%LVM) were: 0% [interquartile range, IQR, 0–0%], in intermediate-risk (3–5p): 5.4% [IQR 0–13.5%] and in high-risk (6–14p): 10.9% [IQR 4.2–12.3%]. ECG-score > 2p had a sensitivity and specificity of 79% and 84% to detect positive LGE on CMR and 77% vs. 75% to detect perfusion defects in sarcomeric mutations carriers. In patients with myocardial fibrosis as identified by LGE, median ECG risk-score was 8p [range 3–10p]. In conclusions, ECG risk-score > 2 p could be used as a cut-off for screening of myocardial fibrosis. Thus ECG risk-score is an inexpensive complementary tool in risk stratification of HCM in the young.

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.

Introduction: Sudden cardiac death (SCD) and early onset cardiomyopathy (CM) in the young will always lead to suspicion of an underlying genetic disorder. Incited by the rapid advances in genetic testing for disease we have revisited families, which previously tested &ldquo, gene-negative&rdquo, for familial predominantly pediatric CM, in hopes of finding a causative gene variant. Methods: 10 different families with non-syndromic pediatric CM or hypertrophic cardiomyopathy (HCM) with severe disease progression and/or heredity for HCM/CM related SCD with &ldquo, results were included. The index patient underwent genetic testing with a recently updated gene panel for CM and SCD. In case of failure to detect a pathogenic variant in a relevant gene, the index patient and both parents underwent clinical (i.e., partial) exome sequencing (trio-exome) in order to catch pathogenic variants linked to the disease in genes that were not included in the CM panel. Results: The mean age at clinical presentation of the 10 index cases was 12.5 years (boys 13.4 years, n = 8, girls 9 years, n = 2) and the family history burden was 33 HCM/CM cases including 9 HCM-related SCD and one heart transplantation. In 5 (50%) families we identified a genetic variant classified as pathogenic or likely pathogenic, in accordance with the American College of Medical Genetics and Genomics (ACMG) criteria, in MYH7 (n = 2), RBM20, ALPK3, and PGM1, respectively, and genetic variants of unknown significance (VUS) segregating with the disease in an additional 3 (30%) families, in MYBPC3, ABCC9, and FLNC, respectively. Conclusion: Our results show the importance of renewed thorough clinical assessment and the necessity to challenge previous genetic test results with more comprehensive updated gene panels or exome sequencing if the initial test failed to identify a causative gene for early onset CM or SCD in children. In pediatric cardiomyopathy cases when the gene panel still fails to detect a causative variant, a trio exome sequencing strategy might resolve some unexplained cases, especially if a multisystemic condition is clinically missed.

BackgroundInfants with congenital heart disease (CHD) have an increased risk of morbidity and mortality during a respiratory syncytial virus (RSV) infection. The aim of this study was to estimate the cost-effectiveness of palivizumab as RSV-prophylaxis among infants with CHD, including the effect of delayed heart surgery and asthma.MethodsA simulation model with data from the literature and health care authorities including costs and utilities was developed to estimate costs and health effects over a lifetime for a cohort of CHD infants receiving palivizumab compared to no RSV-prophylaxis.ResultsThe prophylaxis treatment incurred a cost of 3664 EUR per treated infant. However, due to cost-savings from primarily avoiding hospitalizations (5145 EUR/treated infant) and avoiding heart complications due to delayed heart surgery (2082 EUR/treated infant), the RSV-prophylaxis treatment resulted in a total cost-saving of 3833 EUR per treated infant. At the same time, the prophylaxis-treated cohort accumulated more life-years and higher quality of life than the non-prophylaxis cohort.ConclusionThis study confirms that RSV-prophylaxis in severe CHD infants less than one year of age is cost beneficial. Avoiding delayed heart surgeries is an important benefit of prophylaxis and should be taken into consideration.

Respiratory tract infections (RTI) are common among young children, and congenital heart defect (CHD) is a risk factor for severe illness and hospitalization. This study aims to assess the relative risk of hospitalization due to RTI in winter and summer seasons for different types of CHD. All children born in Sweden and under the age of two, in 2006-2011, were included. Heart defects were grouped according to type. Hospitalization rates for respiratory syncytial virus (RSV) infection and RTI in general were retrieved from the national inpatient registry. The relative risk of hospitalization was calculated by comparing each subgroup to other types of CHD and otherwise healthy children. The relative risk of hospitalization was increased for all CHD subgroups, and there was a greater increase in risk in summer for the most severe CHD. This included RSV infection, as well as RTI in general. The risk of hospitalization due to RTI is greater for CHD children. Prophylactic treatment with palivizumab, given to prevent severe RSV illness, is only recommended during winter. We argue that information to healthcare staff and parents should include how the risk of severe infectious respiratory tract illnesses, RSV and others, is present all year round for children with CHD.

Aims To determine if myocardial perfusion (MP) during hyperaemia is decreased in young patients with hypertrophic cardiomyopathy (HCM). Also, to determine if an MP decrease is associated with diastolic dysfunction, and to investigate if young subjects at risk of HCM show differences in MP compared with controls. Methods and results This study included 10 HCM patients (age 22.3 ± 6.4 years), 14 subjects at risk for HCM ‘HCM risk’ (age 18.9 ± 3.8 years), and 12 controls (age 22.8 ± 4.5 years). HCM patients were examined at rest and during hyperaemia (adenosine 140 µg/kg/min) with cardiovascular magnetic resonance (CMR) and echocardiography. MP was calculated as the ratio of coronary sinus flow and left ventricular mass (LVM) from CMR. Myocardial fibrosis was assessed using late gadolinium enhancement. Diastolic function was quantified with both echocardiography and CMR. At rest, MP (mL/min/g) was similar in the control, HCM risk, and HCM patients (0.8 ± 0.1, 1.0 ± 0.1, and 0.9 ± 0.1, respectively, P = ns). During adenosine, MP was lower in HCM patients (2.5 ± 0.4, P < 0.05) compared with both HCM risk (5.0 ± 0.5) and controls (3.9 ± 0.3). Subjects at HCM risk showed no significant difference in MP during adenosine compared with controls. One HCM patient showed mild diastolic dysfunction. Neither controls nor HCM risk individuals showed any sign of myocardial fibrosis, whereas 7/10 HCM patients had fibrosis (5 ± 1% of the total LVM). Conclusion Young individuals with HCM, but not those at risk, show decreased MP during hyperaemia compared with controls even in the absence of diastolic dysfunction or LV outflow obstruction. These results may suggest that microvascular disease contributes to the decreased MP in the investigated population.

Introduction Sudden cardiac death (SCD) in the young is rare and should always lead to suspicion of a genetic cardiac disorder. We describe a family, in which the proband was a girl deceased by sudden cardiac death in the playground at thirteen years of age. The index-patient had short stature, cleft palate but no previous cardiac symptoms. We found an uncommon cause of cardiomyopathy, due to a congenital disorder of glycosylation (CDG), previously described to cause a variable range of usually mild symptoms, and not previously found to cause SCD as the first symptom of the condition. Methods The index patient underwent postmortem genetic testing/molecular autopsy for genes known to cause SCD, without a detection of causative agent, why two siblings of similar phenotype as the deceased sister underwent clinical-exome genetic sequencing (next generation sequencing). All first-degree relatives underwent clinical examination including cardiac ultrasound, Holter-ECG, exercise stress test and biochemistry panel. Results A genetic variant in the gene for phosphoglucomutase 1 (PGM1) was identified in the index patient and her two brothers, all were found to be homozygous for the genetic variant (G230E) NM_002633.2:c.689 G > A in PGM1. This variant has been linked to a congenital disorder of glycosylation (PGM1-CDG), explaining the clinical picture of short stature, cleft palate, liver engagement and cardiomyopathy. During follow-up one of the brothers died unexpectedly after physical exertion during daily life at the age of twelve years. The other brother fainted during similar circumstances at the age of thirteen years. Both parents and three other siblings were found to be heterozygous gene carriers without risk for the disease. Conclusion Our findings suggest that there is a need of multidisciplinary discussion and genetic testing after unexpected cardiac death in the young. We have to be more flexible in our evaluation of diseases and to consider even uncommon diseases including rare recessive inherited disorders. Our findings also suggest that the autosomal recessive PGM1-CDG might be highly associated with life-threatening cardiomyopathy with arrhythmia or sudden cardiac death as the first symptom presenting from childhood and adolescence.

Andersen-Tawil syndrome (ATS) is a rare inherited multisystem disorder associated with mutations in KCNJ2 and low prevalence of life-threatening ventricular arrhythmias. Our aim was to describe the clinical course of ATS in a family, in which the proband survived aborted cardiac arrest (ACA) and genetic screening revealed a previously unknown mutation (c.271_282del12[p.Ala91_Leu94del]) in the KCNJ2 gene.

Objective: To establish which risk factors are predictive for sudden death in hypertrophic cardiomyopathy (HCM) diagnosed in childhood. Methods: A Swedish national cohort of patients with HCM diagnosed 2 years (n=100), and features significantly more common in SD/CA group were further analysed with univariate and multivariate Cox hazard regression in the total cohort. Results: Ranked according to relative risk (RR) the ECG risk score >5 points had an RR of 46.5 (95% CI 6.6 to 331), sensitivity of 97% (83% to 100%) and specificity of 80% (71% to 88%) (p4.5: 9.9 (3.1 to 31.2); septal thickness ≥190% of upper limit of normal for age (septum in % of 95th centile for age (SEPPER) ≥190%): 7.9 (3.2 to 19.4); ventricular tachycardia: 9.1 (3.6 to 22.8); ventricular ectopics on exercise testing: 7.4 (2.7 to 20.2); and left ventricular outflow gradient (left ventricular outflow tract obstruction (LVOTO)) >50 mm Hg: 6.6 (4.0 to 11.0). Family history was non-significant. Multivariate Cox hazard analysis gives the following as early predictors: limb-lead QRS amplitude sum (p=0.020), SEPPER ≥190% (p

The objective of the study was to investigate the antigen specificity and occurrence of individual autoantibodies in mothers of children diagnosed with atrioventricular (AV) block in a nation-wide setting. Patients with AV block detected before 15 years of age were identified using national quality registries as well as a network of pediatric and adult cardiologists and rheumatologists at the six university hospitals in Sweden. Patients with gross heart malformations, surgically or infectiously induced blocks were excluded. Blood samples were obtained from the mothers and maternal autoantibody profile, including the occurrence of antibodies against Ro52, Ro60, La, SmB, SmD, RNP-70k, RNP-A, RNP-C, CENP-C, Scl-70, Jo-1, ribosomal RNP and histones was investigated in 193 mothers of children with AV block by immunoblotting and ELISA. Autoantibody reactivity was detected in 48% (93/193) of the mothers of children with AV block. In autoantibody-positive mothers, the vast majority, 95% (88/93), had antibodies against Ro52, while 63% (59/93) had autoantibodies to Ro60 and 58% (54/93) had autoantibodies to La. In addition, 13% (12/93) of the autoantibody-positive mothers had antibodies to other investigated antigens besides Ro52, Ro60 and La, and of these anti-histone antibodies were most commonly represented, detected in 8% (7/93) of the mothers. In conclusion, this Swedish population-based study confirm that maternal autoantibodies may associate with heart block in the child. Further, our data demonstrate a dominant role of Ro52 antibodies in association with AV block.

Influence of season of birth and maternal age in the development of congenital heart block in anti-Ro-SSA/La-SSB positive pregnancies

Introduction The conventional ECG is commonly used to screen for hypertrophic cardiomyopathy (HCM), but up to 25% of adults and possibly larger percentages of children with HCM have no distinctive abnormalities on the conventional ECG, whereas 5 to 15% of healthy young athletes do. Recently, a 5-min resting advanced 12-lead ECG test ("A-ECG score") showed superiority to pooled criteria from the strictly conventional ECG in correctly identifying adult HCM. The purpose of this study was to evaluate whether in children and young adults, A-ECG scoring could detect echocardiographic HCM associated with the MYBPC3 genetic mutation with greater sensitivity than conventional ECG criteria and distinguish healthy young controls and athletes from persons with MYBPC3 HCM with greater specificity. Methods Five-minute 12-lead ECGs were obtained from 15 young patients (mean age 13.2 years, range 0-30 years) with MYBPC3 mutation and phenotypic HCM. The conventional and A-ECG results of these patients were compared to those of 198 healthy children and young adults (mean age 13.2, range 1 month-30 years) with unremarkable echocardiograms, and to those of 36 young endurance-trained athletes, 20 of whom had athletic (physiologic) left ventricular hypertrophy. Results Compared with commonly used, age-specific pooled criteria from the conventional ECG, a retrospectively generated A-ECG score incorporating results from just 2 derived vectorcardiographic parameters (spatial QRS-T angle and the change in the vectorcardiographic QRS azimuth angle from the second to the third eighth of the QRS interval) increased the sensitivity of ECG for identifying MYBPC3 HCM from 46% to 87% (p

Hypertrophic cardiomyopathy (HCM) is the main cause of sudden cardiac death in the young. Adult patients with HCM appear to have functional abnormalities in the coronary circulation and also in the peripheral vessels. The aim of present study was to assess peripheral vascular function and myocardial

Aim: This is the first study to evaluate compliance with the 2003 Swedish national guidelines for prophylactic treatment of respiratory syncytial virus (RSV) in children with congenital heart disease (CHD). We estimated the relative risk (RR) of children with CHD being hospitalised with a RSV infection, studied the extent to which RSV prophylactic treatment with palivizumab corresponded to the guidelines and determined the morbidity of children with CHD who developed RSV infection despite prophylaxis. Methods: This national observational study comprised prospectively registered data on 219 children with CHD treated with palivizumab, medical records on RSV cases and information on hospitalisation rates of children with CHD and RSV infection. Results: The calculated RR of children with CHD being hospitalised with RSV infection was 2.06 (950/0 Cl 1.6-2.6; p < 0.0001) compared with children without CHD. Approximately half of the patients (49%) born before the RSV season and 25% born during the RSV season did not start treatment as recommended by the guidelines. Conclusion: Having CHD increased the rate and estimated RR of children being hospitalised with RSV infection. The guidelines were not followed for about half of the children born before a RSV season and a quarter of the children born during a RSV season and need updating.

Objective Congenital heart block may develop in the fetuses of Ro/SSA-positive and La/SSB-positive mothers. Recurrence rates of only 10-20% despite persisting maternal antibodies indicate that additional factors are critical for the establishment of heart block. The authors investigated the influence of other maternal and fetal factors on heart block development in a Swedish population-based cohort. less thanbrgreater than less thanbrgreater thanMethods The influence of fetal gender, maternal age, parity and time of birth on heart block development was analysed in 145 families, including Ro/La-positive (n=190) and Ro/La-negative (n=165) pregnancies. less thanbrgreater than less thanbrgreater thanResults There was a recurrence rate of 12.1% in Ro/La-positive women, and no recurrence in Ro/La-negative women. Fetal gender and parity did not influence the development of heart block in either group. Maternal age in Ro/La-positive pregnancies with a child affected by heart block was, however, significantly higher than in pregnancies resulting in babies without heart block (pandlt;0.05). Seasonal timing of pregnancy influenced the outcome. Gestational susceptibility weeks 18-24 occurring during January-March correlated with a higher proportion of children with heart block and lower vitamin D levels during the same period in a representative sample of Swedish women and a corresponding higher proportion of children with heart block born in the summer (pandlt;0.02). Maternal age or seasonal timing of pregnancy did not affect the outcome in Ro/La-negative pregnancies. less thanbrgreater than less thanbrgreater thanConclusion This study identifies maternal age and seasonal timing of pregnancy as novel risk factors for heart block development in children of Ro/La-positive women. These observations may be useful for counselling when pregnancy is considered. Funding Agencies|KIRCNET (Karolinska Institutet Circulation and Respiratory Research Network)||Magn. Bergvalls Foundation||Jerring Foundation||Stiftelsen Samariten||Karolinska Institute||Royal Swedish Academy of Sciences||Swedish Research Council||Goran Gustafsson Foundation||Torsten and Ragnar Soderberg Foundation||King Gustaf Vth 80-Year Foundation||Swedish Foundation for Strategic Research||Heart-Lung Foundation||Swedish Rheumatism Association

Recurrent copy number variants (CNVs) are found in a significant proportion of patients with congenital heart disease (CHD) and some of these CNVs are associated with other developmental defects. In some syndromic patients, CHD may be the first presenting symptom, thus screening of patients with CHD for CNVs in specific genomic regions may lead to early diagnosis and awareness of extracardiac symptoms. We designed a multiplex ligation-dependent probe amplification (MLPA) assay specifically for screening of CHD patients. The MLPA assay allows for simultaneous analysis of CNVs in 25 genomic regions previously associated with CHD. We screened blood samples from 402 CHD patients and identified 14 rare CNVs in 13 (3.2%) patients. Five CNVs were de novo and six where inherited from a healthy parent. The MLPA screen led to early syndrome diagnosis in two of these patients. We conclude that the MLPA assay detects clinically relevant CNVs and suggest that it could be used within pediatric cardiology as a first tier screen to detect clinically relevant CNVs and identify syndromic patients at an early stage. (C) 2012 Wiley Periodicals, Inc. (Less)

Background and objectives Congenital heart block (CHB) may develop in the fetus of anti-Ro/SSA and anti-La/SSB positive mothers. Reported recurrence rates of only 10–20% despite persisting maternal antibodies indicate that additional factors are critical for establishment of the heart block. The authors therefore investigated the influence of other maternal and fetal factors on heart block development in a Swedish population-based cohort. Material and methods The influence of fetal gender, maternal age, parity and time of birth on heart block development was analysed in 145 families including Ro/La-positive (n= 190) and Ro/La-negative (n=165) pregnancies. Results The authors observed a recurrence rate for heart block of 12.1% in Ro/La-positive women, and no recurrence in Ro/La-negative women. Fetal gender and parity did not influence the development of heart block in either group. Maternal age in Ro/La-positive pregnancies with a child affected by heart block was however significantly higher than in pregnancies resulting in babies without heart block (p Conclusions This study identifies maternal age and seasonal timing of pregnancy as novel risk factors for CHB development in Ro/La positive pregnancy. These observations will be important for counselling when a pregnancy is considered.

The relationship between hypertrophy, perfusion abnormalities and fibrosis is unknown in young patients with hypertrophic cardiomyopathy (HCM). Since mounting evidence suggests causal relationship between myocardial ischemia and major adverse cardiac events, we sought to investigate whether (1) regional myocardial perfusion is decreased in young HCM patients and in individuals at risk of HCM, and (2) hypoperfused areas are larger than areas with fibrosis. HCM patients (n = 12), HCM-risk subjects (n = 15) and controls (n = 9) were imaged on a 1.5 T MRI scanner. Myocardial hypertrophy was assessed on cine images. Perfusion images were acquired during adenosine hyperemia and at rest. Maximum upslope ratios of perfusion (stress/rest) were used for semiquantitative analysis. Fibrosis was assessed by late gadolinium enhancement (LGE). Results are presented as median and range. Perfusion in HCM-risk subjects and in non-hypertrophied segments in HCM patients showed no difference compared to controls (P = ns). Hypertrophic segments in HCM patients without LGE showed decreased perfusion compared to segments without hypertrophy [1.5 (1.1-2.3) vs. 2.0 (1.8-2.6), P < 0.001], and hypertrophic segments with LGE showed even lower perfusion using a segmental analysis [0.9 (0.6-1.8), P < 0.05]. The extent of hypoperfused myocardium in HCM patients during adenosine exceeded the extent of fibrosis on LGE [20 (0-48) vs. 4 (0-7) % slice area, P < 0.05] and hypoperfused areas at rest (P < 0.001). Regional perfusion is decreased in hypertrophied compared to non-hypertrophied myocardium and is lowest in fibrotic myocardium in young HCM patients but does not discriminate HCM-risk subjects from controls. The stress-induced hypoperfused regions exceed regions with LGE, indicating that hypoperfusion precedes fibrosis and may be a more sensitive marker of diseased myocardium in HCM.

Methods Twelve controls (22.8 ± 4.5 years), fourteen subjects at risk (18.9 ± 3.8) and ten HCM patients (22.3 ± 6.4) were examined using echocardiography and cardiovascular magnetic resonance (CMR) at rest and during hyperemia (adenosine 140 μg/kg/min). Patients with left ventricular outflow tract obstruction were excluded from the study. Myocardial perfusion was calculated as the ratio of coronary sinus flow and left ventricular mass (LVM) from CMR. Myocardial fibrosis was assessed using late gadolinium enhancement. Diastolic function was quantified using both echocardiography and CMR. The Mann-Whitney test was used to compare the groups and results were considered significant if p < 0.05. Results are presented as mean ± SEM if not otherwise stated. The study was approved by the Ethical Board and informed consent was obtained. Results There was no significant difference in MP (ml/min/g) at rest in controls, subjects at risk and HCM patients (0.8 ± 0.1, 1.0 ± 0.1, 0.9 ± 0.1, respectively, p = ns). During hyperemia, MP was similar in controls and subjects at risk (3.9 ± 0.3 and 5.0 ± 0.5, p = 0.11, but lower in HCM patients (2.5 ± 0.4, p < 0.05 compared to both). Even when fibrosis was excluded from LVM the MP was lower in HCM patients compared to the other groups. Two subjects showed mild diastolic dysfunction (E/e’ = 16), otherwise none of the investigated subjects showed marked diastolic dysfunction (E/e’