Clinical Risk Score to Predict Pathogenic Genotypes in Patients With Dilated Cardiomyopathy

BACKGROUND

Although genotyping allows family screening and influences risk-stratification in patients with nonischemic dilated cardiomyopathy (DCM) or isolated left ventricular systolic dysfunction (LVSD), its result is negative in a significant number of patients, limiting its widespread adoption.

OBJECTIVES

This study sought to develop and externally validate a score that predicts the probability for a positive genetic test result (G+) in DCM/LVSD.

METHODS

Clinical, electrocardiogram, and echocardiographic variables were collected in 1,015 genotyped patients from Spain with DCM/LVSD. Multivariable logistic regression analysis was used to identify variables independently predicting G+, which were summed to create the Madrid Genotype Score. The external validation sample comprised 1,097 genotyped patients from the Maastricht and Trieste registries.

RESULTS

A G+ result was found in 377 (37%) and 289 (26%) patients from the derivation and validation cohorts, respectively. Independent predictors of a G+ result in the derivation cohort were: family history of DCM (OR: 2.29; 95% CI: 1.73-3.04; P < 0.001), low electrocardiogram voltage in peripheral leads (OR: 3.61; 95% CI: 2.38-5.49; P < 0.001), skeletal myopathy (OR: 3.42; 95% CI: 1.60-7.31; P = 0.001), absence of hypertension (OR: 2.28; 95% CI: 1.67-3.13; P < 0.001), and absence of left bundle branch block (OR: 3.58; 95% CI: 2.57-5.01; P < 0.001). A score containing these factors predicted a G+ result, ranging from 3% when all predictors were absent to 79% when ≥4 predictors were present. Internal validation provided a C-statistic of 0.74 (95% CI: 0.71-0.77) and a calibration slope of 0.94 (95% CI: 0.80-1.10). The C-statistic in the external validation cohort was 0.74 (95% CI: 0.71-0.78).

CONCLUSIONS

The Madrid Genotype Score is an accurate tool to predict a G+ result in DCM/LVSD.

Combination of late gadolinium enhancement and genotype improves prediction of prognosis in non-ischemic dilated cardiomyopathy

Aims

Genotype and left ventricular scar on cardiac magnetic resonance (CMR) are increasingly recognized as risk markers for adverse outcomes in non‐ischaemic dilated cardiomyopathy (DCM). We investigated the combined influence of genotype and late gadolinium enhancement (LGE) in assessing prognosis in a large cohort of patients with DCM.

Methods and results

Outcomes of 600 patients with DCM (53.3 ± 14.1 years, 66% male) who underwent clinical CMR and genetic testing were retrospectively analysed. The primary endpoints were end‐stage heart failure (ESHF) and malignant ventricular arrhythmias (MVA). During a median follow‐up of 2.7 years (interquartile range 1.3–4.9), 24 (4.00%) and 48 (8.00%) patients had ESHF and MVA, respectively. In total, 242 (40.3%) patients had pathogenic/likely pathogenic variants (positive genotype) and 151 (25.2%) had LGE. In survival analysis, positive LGE was associated with MVA and ESHF (both, p < 0.001) while positive genotype was associated with ESHF (p = 0.034) but not with MVA (p = 0.102). Classification of patients according to genotype (G+/G−) and LGE presence (L+/L−) revealed progressively increasing events across L−/G−, L−/G+, L+/G− and L+/G+ groups and resulted in optimized MVA and ESHF prediction (p < 0.001 and p = 0.001, respectively). Hazard ratios for MVA and ESHF in patients with either L+ or G+ compared with those with L−/G− were 4.71 (95% confidence interval: 2.11–10.50, p < 0.001) and 7.92 (95% confidence interval: 1.86–33.78, p < 0.001), respectively.

Conclusion

Classification of patients with DCM according to genotype and LGE improves MVA and ESHF prediction. Scar assessment with CMR and genotyping should be considered to select patients for primary prevention implantable cardioverter‐defibrillator placement.

Outcomes of patients with left ventricular noncompaction and preserved ejection fraction

Funding Acknowledgements

Type of funding sources: None.

INTRODUCTION 

Left ventricular noncompaction (LVNC) is a poorly defined entity with heterogeneous prognosis. LV ejection fraction (LVEF) is one of the main predictors of major adverse cardiovascular events (MACE). However, outcomes of LVNC patients with preserved LVEF (pEF) remain uncertain.

PURPOSE 

The aim of our study was to determine the incidence and predictors of MACE in LVNC patients with pEF as well as to assess the evolution of LVEF throughout follow-up. 

METHODS 

We conducted a retrospective, longitudinal, multicentre cohort study. Consecutive patients with transthoracic echocardiography (TTE) and/or cardiac magnetic resonance (CMR) diagnostic criteria for LVNC and initially pEF (LVEF≥50%) were recruited. MACE were defined as a composite of heart failure (HF), ventricular arrhythmias (VA), systemic embolisms (SE) and/or all-cause mortality. Progressive systolic dysfunction was defined as an LVEF &lt; 50% at last TTE and/or an absolute ≥10-point decrease in LVEF from first to last TTE. Lower limit of LVEF CMR values were considered 50-57% according to current recommendations. Cox-regression analysis was used for MACE and logistic regression was used for progressive systolic dysfunction (only first and last TTE were available).

RESULTS 

A total of 305 patients from 12 centres were included from 2000 to 2018. Age was 38 ± 19 years and 165 (54%) were men. LVEF was 62 ± 8% and 8% had late gadolinium enhancement (LGE). During a median follow-up of 4.7 (IQR 2.1-7.4) years, MACE occurred in 40 (13%) patients with an incidence rate of 2.73 (95% CI 2.00-3.72) events per 100 person-years: 8 HF, 27 VA, 3 SE and 5 deaths. LVEF by CMR (HR 0.95, 95% CI 0.91-0.99, p = 0.0048) and hypertension (HR 2.30, 95% CI 1.08-4.89, p = 0.031) were the only variables independently associated with the endpoint. Patients with lower limit LVEF values showed an increased risk of MACE (Figure 1). LGE was not associated.

Sixty-one (21%) patients experienced progressive systolic dysfunction: 31 (11%) had an LVEF &lt; 50% and 48 (17%) an absolute ≥10-point decrease in LVEF at last follow-up. On multivariate analysis, LVEF by CMR was the only independent predictor (OR 0.93, 95% CI 0.89-0.98, p = 0.008). Patients with lower limit LVEF values had an increased risk (Figure 2). In this subgroup, LGE was also associated with the endpoint (HR 10.69, 95% CI 1.97-58.13, p = 0.006).

CONCLUSIONS 

Patients with left ventricular noncompaction and preserved ejection fraction carry a moderate risk of major adverse cardiovascular events and progressive systolic dysfunction. LVEF remains the main predictor of outcomes in this subgroup. Patients with lower limit LVEF values are at increased risk, probably suggesting subclinical systolic dysfunction. Therefore, they should be carefully monitored. Abstract Figure. Kaplan Meier cuves for MACE  Abstract Figure. Risk of progressive systolic dysfunction

[Myotonic dystrophy type 1: a series of 107 patients]

INTRODUCTION

Myotonic dystrophy type 1 is the most common muscular dystrophy in adults. It is a genetic disorder of autosomal dominant inheritance and one of its most striking features is its multi-systemic involvement with a wide clinical phenotype.

PATIENTS AND METHODS

Data from 107 patients with a genetically confirmed diagnosis of the disease were retrospectively analysed from the database of a national reference division for neuromuscular diseases. Demographic and clinical data were collected over a 7-year period.

RESULTS

The most frequent age of symptom onset was adulthood (66.4%). 35% showed exclusive distal weakness and a majority (63.6%) had clinical myotonia. Only 10 patients lacked neuromuscular symptoms at diagnosis and up to 9.5% were restricted to a wheelchair. The implantation of a pacemaker or cardioverter-defibrillator was conducted in 16 patients but no sudden cardiac death was detected. A venous thromboembolic disease incidence rate of 5.6 cases per 1000 patient-year was identified. More than half of the patients (54%) in the series developed respiratory failure. 13 patients died during the follow-up period, with respiratory failure being the main cause of death.

CONCLUSIONS

The follow-up and clinical management of patients with DM1 should be multidisciplinary. In our series, the main cause of morbidity and mortality was respiratory disorders, whereas the incidence of cardiac disorders was lower. In addition, there is a notable frequency of complications derived from falls, which can have serious consequences. Finally, a higher than expected incidence of thromboembolic events was identified, which deserves further study in other cohorts of patients.

Novel genetic and molecular pathways in pulmonary arterial hypertension associated with connective tissue disease

Introduction

PAH is a severe complication of CTD, with remarkable morbidity and mortality. SSc is most commonly associated with PAH, but it can be present in other CTD. Despite major advances in PAH therapy, survival in CTD-PAH remains poor. Furthermore, the molecular and genetic basis of PAH in CTD are not well established.

Purpose

This study aimed to screen for genetic defects in a cohort of patients with CTD-PAH.

Methods

Since November 2011, genetic testing is offered to all patients with idiopathic, hereditable and associated forms of PAH, and PVOD included in a national registry of PAH. A PAH-specific panel of 35 genes was designed.

Results

During enrolling, 79 patients were recruited: 59 SSc, 11 SLE and 9 other. 69 female, mean age 55,6±1,9 years, mean PVR 8,6±0,5 WU and mean DLCO 47,5±2%. Disease-associated variants were observed in 9 patients: 4 pathogenic/likely pathogenic in 4 different genes (TBX4, ABCC8, KCNA5 and GDF2/BMP9) and 5 VUS in 4 genes (ABCC8, NOTCH3, TOPBP1 and CTCFL). Clinical characteristics of patients with pathogenic/likely pathogenic variants and variant analyses are shown in Tables 1 and 2.

Patient 1 is a Caucasian female with mixed CTD, diagnosed with PAH at 58 years of age. She has a frameshift pathogenic variant in TBX4. Pulmonary function test (PFT) ruled out interstitial lung disease (ILD), but a reduction in DLCO was observed (61% of predicted).

Two patients carry variants in ABCC8. Patient 2 is a Caucasian female with SSc, diagnosed with PAH at 27 years of age. She carries a splicing variant in ABCC8, classified as likely pathogenic. Her mother was diagnosed with PAH associated with a repaired ASD at 61 years of age. In the genetic testing, no variants were observed in PAH genes. DLCO was 71% of predicted, without signs of ILD. Patient 3 is a Caucasian male, with clinical suspicion of PVOD associated with SSc and HIV infection. PAH was diagnosed at 57 years of age. He presented a missense variant in ABCC8, located in a gating regulatory region, and classified as VUS. Her sister was also diagnosed with PVOD associated with SSc at 48 years of age. No blood or tissue samples are available. In patient 3, DLCO was 22% of predicted value. CT scan showed the typical triad of PVOD.

Patient 4 is a Latin American female with SLE, diagnosed with PAH at 25 years of age. She presented a pathogenic nonsense variant in GDF2/BMP9.

Patient 5 is a Caucasian female with SSc, diagnosed with PAH at 70 years of age. She presented a pathogenic variant in KCNA5.

Patients 6–9 have SSc-PAH and carry VUS in NOTCH1, CTCFL, CTCFL and TOPBP1, respectively.

Conclusions

We demonstrate the practical diagnostic utility of genetic testing with a panel in CTD-PAH. The discovery of rare variants in these patients forces us to take a comprehensive approach and accurate genetic counseling. Further research is still necessary to confirm these findings and help to provide a personalized medicine approach to these patients.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This project was founded by project “Bases Genético Moleculares de la Medicina de Precisiόn en la Hipertensiόn Arterial Pulmonar”. Funder: Instituto Carlos III. Ministerio de Economía y Competitividad.

Association of Left Ventricular Systolic Dysfunction Among Carriers of Truncating Variants in Filamin C With Frequent Ventricular Arrhythmia and End-stage Heart Failure

Importance

Truncating variants in the gene encoding filamin C (FLNCtv) are associated with arrhythmogenic and dilated cardiomyopathies with a reportedly high risk of ventricular arrhythmia.

Objective

To determine the frequency of and risk factors associated with adverse events among FLNCtv carriers compared with individuals carrying TTN truncating variants (TTNtv).

Design, Setting, and Participants

This cohort study recruited 167 consecutive FLNCtv carriers and a control cohort of 244 patients with TTNtv matched for left ventricular ejection fraction (LVEF) from 19 European cardiomyopathy referral units between 1990 and 2018. Data analyses were conducted between June and October, 2020.

Main Outcomes and Measures

The primary end point was a composite of malignant ventricular arrhythmia (MVA) (sudden cardiac death, aborted sudden cardiac death, appropriate implantable cardioverter-defibrillator shock, and sustained ventricular tachycardia) and end-stage heart failure (heart transplant or mortality associated with end-stage heart failure). The secondary end point comprised MVA events only.

Results

In total, 167 patients with FLNCtv were studied (55 probands [33%]; 89 men [53%]; mean [SD] age at baseline evaluation, 43 [18] years). For a median follow-up of 20 months (interquartile range, 7-60 months), 29 patients (17.4%) reached the primary end point (19 patients with MVA and 10 patients with end-stage heart failure). Eight (44%) arrhythmic events occurred among individuals with baseline mild to moderate left ventricular systolic dysfunction (LVSD) (LVEF = 36%-49%). Univariable risk factors associated with the primary end point included proband status, LVEF decrement per 10%, ventricular ectopy (≥500 in 24 hours) and myocardial fibrosis detected on cardiac magnetic resonance imaging. The LVEF decrement (hazard ratio [HR] per 10%, 1.83 [95% CI, 1.30-2.57]; P < .001) and proband status (HR, 3.18 [95% CI, 1.12-9.04]; P = .03) remained independent risk factors on multivariable analysis (excluding myocardial fibrosis and ventricular ectopy owing to case censoring). There was no difference in freedom from MVA between FLNCtv carriers with mild to moderate or severe (LVEF ≤35%) LVSD (HR, 1.29 [95% CI, 0.45-3.72]; P = .64). Carriers of FLNCtv with impaired LVEF at baseline evaluation (n = 69) had reduced freedom from MVA compared with 244 TTNtv carriers with similar baseline LVEF (for mild to moderate LVSD: HR, 16.41 [95% CI, 3.45-78.11]; P < .001; for severe LVSD: HR, 2.47 [95% CI, 1.04-5.87]; P = .03).

Conclusions and Relevance

The high frequency of MVA among patients with FLNCtv with mild to moderate LVSD suggests that higher LVEF values than those currently recommended should be considered for prophylactic implantable cardioverter-defibrillator therapy in FLNCtv carriers.

Prognostic role of cardiac magnetic resonance in left ventricular noncompaction

Funding Acknowledgements

Type of funding sources: None.

Background

Left ventricular noncompaction (LVNC) is a heterogeneous entity with a wide phenotypic expression. Risk factors have not been well established and prognostic stratification remains challenging.

Purpose

Describe prognostic role of CMR on long term outcomes of LVNC patients. 

Methods

 

Retrospective multicentric longitudinal cohort study of consecutive patients fulfilling imaging diagnostic criteria for LVNC (Jenni echo criteria and Petersen and Jacquier CMR criteria). Demographic, ECG, genetic, family and treatment variables were recorded. Baseline CMR was used for the analysis. LV ejection fraction (LVEF) was categorized according to heart failure (HF) guidelines and late gadolinium enhancement (LGE) was visually assessed in a binary way. End points were HF, ventricular arrhythmias (VA), systemic embolisms (SE) and all-cause death. Major adverse cardiovascular events (MACE) were the combination of the four previous end points. In patients with initially preserved LVEF (≥ 50%), LV adverse remodelling (LVAR) was defined as an LVEF &lt; 50% and/or absolute decrease of ≥10% in LVEF at last follow-up.

Results

585 patients from 12 referral centres were included from 2000 to 2018. Age at diagnosis was 45 ± 20 years, 334 (57%) were male, baseline LVEF was 48 ± 17% and 18% presented LGE. During a median follow-up of 5.1 years (IQR 2.3-8.1), 110 (19%) patients presented HF, 87 (15%) VA, 18 (3%) SE and 34 (6%) died. MACE occurred in 223 (38%) patients.

LVEF was independently associated with HF, VA, SE and MACE: HR were 1.08, 1.02, 1.04 and 1.02 respectively (all p &lt; 0.05). LGE was more frequent in patients with reduced LVEF (39 Vs 53%, p &lt; 0.001) and was associated with higher HF and VA risk in patients with an LVEF &gt; 35% (HR 2.69 and 2.48 respectively, p &lt; 0.05) (Figure 1). No MACE (0%) occurred during long-term follow-up in patients with preserved LVEF, no LGE as well as no ECG abnormalities and no family aggregation.

305 (52%) patients presented with initially preserved LVEF, and 230 (75%) of those had LVEF available at last follow-up. LVAR occurred in 50 (22%) patients: 22 (10%) had an LVEF &lt; 50% and 41 (18%) an absolute ≥ 10% decrease in LVEF. LGE was independently associated with LVAR (HR 3.51, p = 0.045) (Figure 2). 

Conclusions

Cardiac magnetic resonance has an important prognostic role in LVNC. LVEF is the most powerful predictor of events. Myocardial fibrosis is associated with worse outcomes in patients without severe systolic dysfunction, as well as with left ventricular adverse remodelling in those with initially preserved LVEF. Besides, CMR may identify a low-risk subgroup of LVNC patients. Therefore, CMR should be used in risk stratification in LVNC.

Prevalence and clinical outcomes of dystrophin-associated dilated cardiomyopathy without severe skeletal myopathy

AIMS

Dilated cardiomyopathy (DCM) associated with dystrophin gene (DMD) mutations in individuals with mild or absent skeletal myopathy is often indistinguishable from other DCM forms. We sought to describe the phenotype and prognosis of DMD associated DCM in DMD mutation carriers without severe skeletal myopathy.

METHODS AND RESULTS

At 26 European centres, we retrospectively collected clinical characteristics and outcomes of 223 DMD mutation carriers (83% male, 33 ± 15 years). A total of 112 individuals (52%) had DCM at first evaluation [n = 85; left ventricular ejection fraction (LVEF) 34 ± 11.2%] or developed DCM (n = 27; LVEF 41.3 ± 7.5%) after a median follow-up of 96 months (interquartile range 5-311 months). DCM penetrance was 45% in carriers older than 40 years. DCM appeared earlier in males and was independent of the type of mutation, presence of skeletal myopathy, or elevated serum creatine kinase levels. Major adverse cardiac events (MACE) occurred in 22% individuals with DCM, 18% developed end-stage heart failure and 9% sudden cardiac death or equivalent. Skeletal myopathy was not associated with survival free of MACE in patients with DCM. Decreased LVEF and increased left ventricular end-diastolic diameter at baseline were associated with MACE. Individuals without DCM had favourable prognosis without MACE or death during follow-up.

CONCLUSIONS

DMD-associated DCM without severe skeletal myopathy is characterized by incomplete penetrance but high risk of MACE, including progression to end-stage heart failure and ventricular arrhythmias. DCM onset is the major determinant of prognosis with similar survival regardless of the presence of skeletal myopathy.

Clinical Phenotypes and Prognosis of Dilated Cardiomyopathy Caused by Truncating Variants in the TTN Gene

BACKGROUND

Truncating variants in the TTN gene (TTNtv) are the commonest cause of heritable dilated cardiomyopathy. This study aimed to study the phenotypes and outcomes of TTNtv carriers.

METHODS

Five hundred thirty-seven individuals (61% men; 317 probands) with TTNtv were recruited in 14 centers (372 [69%] with baseline left ventricular systolic dysfunction [LVSD]). Baseline and longitudinal clinical data were obtained. The primary end point was a composite of malignant ventricular arrhythmia and end-stage heart failure. The secondary end point was left ventricular reverse remodeling (left ventricular ejection fraction increase by ≥10% or normalization to ≥50%).

RESULTS

Median follow-up was 49 (18-105) months. Men developed LVSD more frequently and earlier than women (45±14 versus 49±16 years, respectively; P=0.04). By final evaluation, 31%, 45%, and 56% had atrial fibrillation, frequent ventricular ectopy, and nonsustained ventricular tachycardia, respectively. Seventy-six (14.2%) individuals reached the primary end point (52 [68%] end-stage heart failure events, 24 [32%] malignant ventricular arrhythmia events). Malignant ventricular arrhythmia end points most commonly occurred in patients with severe LVSD. Male sex (hazard ratio, 1.89 [95% CI, 1.04-3.44]; P=0.04) and left ventricular ejection fraction (per 10% decrement from left ventricular ejection fraction, 50%; hazard ratio, 1.63 [95% CI, 1.30-2.04]; P<0.001) were independent predictors of the primary end point. Two hundred seven of 300 (69%) patients with LVSD had evidence of left ventricular reverse remodeling. In a subgroup of 29 of 74 (39%) patients with initial left ventricular reverse remodeling, there was a subsequent left ventricular ejection fraction decrement. TTNtv location was not associated with statistically significant differences in baseline clinical characteristics, left ventricular reverse remodeling, or outcomes on multivariable analysis (P=0.07).

CONCLUSIONS

TTNtv is characterized by frequent arrhythmia, but malignant ventricular arrhythmias are most commonly associated with severe LVSD. Male sex and LVSD are independent predictors of outcomes. Mutation location does not impact clinical phenotype or outcomes.

Mutations in TRIM63 cause an autosomal-recessive form of hypertrophic cardiomyopathy

OBJECTIVE

Up to 50% of patients with hypertrophic cardiomyopathy (HCM) show no disease-causing variants in genetic studies. TRIM63 has been suggested as a candidate gene for the development of cardiomyopathies, although evidence for a causative role in HCM is limited. We sought to investigate the relationship between rare variants in TRIM63 and the development of HCM.

METHODS

TRIM63 was sequenced by next generation sequencing in 4867 index cases with a clinical diagnosis of HCM and in 3628 probands with other cardiomyopathies. Additionally, 3136 index cases with familial cardiovascular diseases other than cardiomyopathy (mainly channelopathies and aortic diseases) were used as controls.

RESULTS

Sixteen index cases with rare homozygous or compound heterozygous variants in TRIM63 (15 HCM and one restrictive cardiomyopathy) were included. No homozygous or compound heterozygous were identified in the control population. Familial evaluation showed that only homozygous and compound heterozygous had signs of disease, whereas all heterozygous family members were healthy. The mean age at diagnosis was 35 years (range 15-69). Fifty per cent of patients had concentric left ventricular hypertrophy (LVH) and 45% were asymptomatic at the moment of the first examination. Significant degrees of late gadolinium enhancement were detected in 80% of affected individuals, and 20% of patients had left ventricular (LV) systolic dysfunction. Fifty per cent had non-sustained ventricular tachycardia. Twenty per cent of patients suffered an adverse cerebrovascular event (20%).

CONCLUSION

TRIM63 appears to be an uncommon cause of HCM inherited in an autosomal-recessive manner and associated with concentric LVH and a high rate of LV dysfunction.

Clinical heterogeneity of Pulmonary Arterial Hypertension associated with variants in TBX4

Background

The knowledge of hereditary predisposition has changed our understanding of Pulmonary Arterial Hypertension. Genetic testing has been widely extended and the application of Pulmonary Arterial Hypertension specific gene panels has allowed its inclusion in the diagnostic workup and increase the diagnostic ratio compared to the traditional sequencing techniques. This is particularly important in the differential diagnosis between Pulmonary Arterial Hypertension and Pulmonary Venoocclusive Disease.

Methods

Since November 2011, genetic testing is offered to all patients with idiopathic, hereditable and associated forms of Pulmonary Arterial Hypertension or Pulmonary Venoocclusive Disease included in the Spanish Registry of Pulmonary Arterial Hypertension. Herein, we present the clinical phenotype and prognosis of all Pulmonary Arterial Hypertension patients with disease-associated variants in TBX4.

Results

Out of 579 adults and 45 children, we found in eight patients from seven families, disease-causing associated variants in TBX4. All adult patients had a moderate-severe reduction in diffusion capacity. However, we observed a wide spectrum of clinical presentations, including Pulmonary Venoocclusive Disease suspicion, interstitial lung disease, pulmonary vascular abnormalities and congenital heart disease.

Conclusions

Genetic testing is now essential for a correct diagnosis work-up in Pulmonary Arterial Hypertension. TBX4-associated Pulmonary Arterial Hypertension has marked clinical heterogeneity. In this regard, a genetic study is extremely useful to obtain an accurate diagnosis and provide appropriate management.

5163Predictors of adverse cardiovascular events in patients with truncating variants in the filamin c (flnc) gene

Background

Truncating variants in Filamin C (FLNCtv) are associated with arrhythmogenic (AC) and dilated cardiomyopathies (DCM). Affected patients are reported to demonstrate a high incidence of arrhythmic and heart-failure related cardiovascular events. The aim of this study was to determine factors that predict adverse events in mutation carriers.

Methods

The study cohort comprised 168 FLNCtv carriers followed at 19 European centres. Baseline and longitudinal follow-up clinical data were collected. The primary endpoint was a composite of sudden cardiac death (SCD), aborted SCD, appropriate implantable cardioverter-defibrillator (ICD) shock, cardiac transplantation (HTx) and mortality from end-stage heart failure (ESHF).

Results

47 different pathogenic or likely-pathogenic FLNCtv were identified in 60 unrelated probands. In those with baseline and longitudinal data (160 patients; 57 probands), 114 (71.3%) patients exhibited evidence of cardiac disease at initial evaluation. Gene penetrance was 85% by the age of 40 years. During a median follow-up of 1.5 years (IQR 4.1), 24 individuals (15%) reached the primary endpoint – 16 arrhythmic (SCD/aborted SCD/ICD shock) and 8 heart failure (ESHF/HTx) related-events. Univariable predictors at baseline evaluation of the composite primary endpoint included proband status (HR 4.0, 95% CI: 1.5–10.9, p=0.01), symptoms of dyspnoea (HR 2.8, 95% CI: 1.2–6.4, p=0.02), LV systolic dysfunction (LVSD) (HR 12.4, 95% CI: 2.9–53.2, p=0.001), frequent ventricular ectopy (VE>500) on 24-hour Holter (HR 9.3, 95% CI: 1.2–74.7, p=0.04) and the presence of late gadolinium enhancement on CMR (HR 8.9, 95% CI: 1.2–68.5, p=0.04).

Multivariable analysis identified LVSD (LVEF <50%) at baseline as an independent predictor of the primary endpoint with a hazard ratio of 8.6 (95% CI: 1.8–41.5, p=0.007). ROC analysis using LV systolic dysfunction to predict the primary endpoint demonstrated an area under the curve of 0.84 (95% CI: 0.76–0.91, p<0.001) and identified an optimal LVEF “cut-off” of 47% for predicting adverse events with a Youden's index of 0.61 (sensitivity 0.91; specificity 0.70).

Kaplan-Meier plot to demonstrate freedom

Conclusions

LVSD is associated with an over 8-fold increase in the hazard of a primary endpoint event in FLNCtv gene carriers indicating that these patients should be considered for implantable cardioverter-defibrillator (ICD) implantation, optimal heart failure medical therapy and close clinical follow-up.

Acknowledgement/Funding

NIHR Biomedical Research Centre; Instituto de Salud Carlos III; DETECTIN-HF project; Wellcome Trust;CIBERCV; EU Regional Development Fund; FEDER.

Ambulatory blood pressure is associated with polymorphic variation in P2X receptor genes

The P2X receptor gene family encodes a series of proteins that function as ATP-gated nonselective ion channels. P2X receptor channels are involved in transducing aldosterone-mediated signaling in the distal renal tubule and are potential candidate genes for blood pressure regulation. We performed a family based quantitative genetic association study in 248 families ascertained through a proband with hypertension to investigate the relationship between common genetic variation in the P2X4, P2X6, and P2X7 genes and ambulatory blood pressure. We genotyped 28 single nucleotide polymorphisms, which together captured the common genetic variability in the 3 genes. We corrected our results for multiple comparisons specifying a false discovery rate of 5%. We found significant evidence of association between the single nucleotide polymorphism rs591874 in the first intron of the P2X7 gene and blood pressure. The strongest association was found for nighttime diastolic blood pressure (P=0.0032), although association was present for both systolic and diastolic blood pressures measured by an observer during the day and at night. Genotypes were associated with a 0.2 SD ( approximately 2.5 mm Hg) difference in night diastolic blood pressure per allele and accounted for approximately 1% of the total variability in this measurement. Other suggestive associations were found, but these were nonsignificant after correction for multiple testing. These genetic data suggest that drugs affecting P2X receptor signaling may have promise as clinical antihypertensive agents.