Identifying proteomic profiles as indicators of disease severity in arrhythmogenic cardiomyopathy

Introduction

Arrhythmogenic cardiomyopathy (ACM) is an inherited heart muscle disease characterized by progressive fibrofatty replacement of the myocardium and ventricular arrhythmias. Biventricular (BiV) involvement may lead to heart failure. This study aimed to investigate characteristic proteomic patterns in plasma of ACM patients, and correlated them with clinical outcome as well as physical exercise, to assess if key soluble molecules may serve as specific biomarkers for ACM, and whether mechanical stress induced by physical exercise may alter proteomic patterns in ACM patients.

Methods

In 38 ACM patients clinical parameters and major adverse cardiovascular events (MACE defined as presence of sustained ventricular tachycardia, ventricular fibrillation, appropriate therapy from implantable cardioverter defibrillator, sudden cardiac death, death related to end-stage heart failure or cardiac transplant) were obtained prospectively during a mean follow-up period of 36 months. All patients received genetic testing using next generation DNA sequencing. Plasma protein expression was analysed using the Proximity Extension Assay (PEA) technology, where a pair of oligonucleotide-labelled antibody probe binds to each targeted protein. In a subgroup of 11 patients blood was drawn immediately before and 3 hours after standardised bicycle exercise testing, and plasma protein expression was compared.

Results

12 patients had ACM with BiV involvement, and 26 patients had isolated right ventricular (RV) involvement. During the follow-up period, 34 patients had a MACE (30% with RV and 14% with BiV). Over 360 proteins were assessed in all ACM patients and compared to 24 healthy controls. The proteomic signature of ACM patients differed significantly compared to controls, and 32 proteins were upregulated in ACM (Figure 1). The proteomic profiles of patients with RV involvement also differed from those with BiV involvement. Most importantly, after exercise, over 40 proteins were upregulated specifically in ACM patients compared to controls, including key pro-inflammatory, adipogenic molecules and also markers of cardiac fibrosis.

Conclusion

Our study shows that ACM patients with RV and BiV involvement have different plasma proteomic profiles compared to healthy controls. Furthermore we were able to demonstrate that, specifically in ACM patients, several pro-inflammatory pathways are upregulated after exercise compared to healthy controls, further elucidating the molecular pathways associated with arrhythmogenicity and disease progression and highlighting the key role of physical stress. Our results may enable the identification of potential future biomarkers for diagnosis and risk stratification and may pave the way for personalized patient specific treatments.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Baugarten Foundation ZurichSwiss National Foundation

A novel diagnostic score to differentiate between athlete"s heart and ARVC

Funding Acknowledgements

Type of funding sources: None.

Background

The 2010 Task Force Criteria (TFC), although representing the current gold standard to diagnose arrhythmogenic right ventricular cardiomyopathy (ARVC), have not been tested to differentiate ARVC from the athlete’s heart. Furthermore, not all 6 diagnostic categories are easy to obtain.

Purpose

We hypothesized that atrial dimensions are useful to differentiate between both entities. Therefore, we developed a new diagnostic score based upon readily available clinical parameters including atrial dimensions on TTE to help distinguishing the athlete’s heart from ARVC in daily clinical practice.

Methods

In this observational study, 37 patients with definite ARVC (from the Zurich ARVC Program) were compared to 68 athletes. Base on ROC analysis, the following echocardiographic, laboratory and electrocardiographic parameters were included in the final score: indexed right/left atrial volumes (RAVI/LAVI ratio), NT-proBNP, RVOT measurements (PLAX and PSAX adjusted for BSA) on TTE, tricuspid annular motion velocity (TAM) on TTE, precordial electrocardiographic T-wave inversions and depolarization abnormalities according to the TFC.

Results

ARVC patients had a higher RAVI/LAVI ratio (1.78 ± 1.6vs0.95 ± 0.3,p < 0.001), lower right-ventricular function (fac:28 ± 9.7vs42.1 ± 4.8%,p < 0.001; TAM:17.9 ± 5.6vs23.3 ± 3.7mm,p < 0.001) and higher serum NT-proBNP levels (491 ± 771vs44.8 ± 50.6ng/l,p < 0.001). Our novel score outperformed the performance of the 2010 TFC using those parameters, which are available in routine clinical practice (AUC95%,p < 0.001(95%CI.91-.99)vs.AUC90%,p < 0.001(95%CI.84-.97). A score value of 7/12 points yielded a specificity of 98% and a sensitivity of 61% for a diagnosis of ARVC.

Conclusions

ARVC patients present with significantly larger RA as compared to athletes, resulting in a greater RAVI/LAVI ratio. Our novel diagnostic score includes readily available clinical parameters and has a high diagnostic accuracy to differentiate between ARVC and the athlete´s heart. Abstract Figure. Novel clinical score

Impact of genetic reclassification on ARVC diagnosis based on the 2010 task force criteria

Introduction

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is an inherited condition, which is associated with potentially life-threatening ventricular arrhythmias in the young. Approximately 60% of patients carry a possibly disease-causing genetic variant.

Purpose

The aim of this study was to investigate the impact of the 2015 American College of Medical Genetics (ACMG) Criteria on ARVC diagnosis based on the 2010 Modified Task Force Criteria (TFC).

Methods

The study included 79 patients from the Swiss ARVC Registry who harbored a genetic variant deemed to be associated with the disease at initial screening, and classified them as definite, borderline or possible ARVC. Every variant found was re-classified on Varsome Genetics, based on the 2015 ACMG Criteria. Clinical information was then assessed at last available follow-up of every patient and ARVC diagnosis was reclassified based on the newest genetic evidence available.

Results

In 42 out of 79 patients (53.2%), genetic variants were reclassified. Out of these, 33 variants (41.8%) were downgraded from pathogenic (P) / likely pathogenic (LP) to either variants of unknown significance (VUS) or benign (B) / likely benign (LB). Three patients (3.8%) were upgraded from VUS / LP to P. Out of the 12 variants initially classified as VUS, 9 (75%) were reclassified as B or LB. Overall, 13 patients (16.5%) were downgraded from their initial diagnosis (11 from definite to borderline and 2 from borderline to possible).

Conclusion

A significant proportion of patients with ARVC diagnosed based on the 2010 TFC were reclassified when the 2015 ACMG Criteria were taken into consideration. These findings may have clinical consequences, particularly for genetic cascade screening of family members of ARVC patients and necessitate reassessment of genetic variants of index patients who were previously diagnosed with ARVC.

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): University Hospital Zurich

Novel plasma biomarkers in arrhythmogenic cardiomyopathy: the role of ST2 and GDF-15 in predicting biventricular involvement

Background

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart muscle disease characterized by fibrofatty replacement of the myocardium and ventricular arrhythmias. Biventricular (BiV) involvement in ARVC may lead to heart failure.

Purpose

This study aimed to investigate the role of novel plasma biomarkers soluble (s)ST2, Galectin-3 (Gal-3) and GDF-15 in predicting BiV involvement and adverse outcomes in ARVC patients.

Methods

ARVC patients from two independent cohorts were studied. 108 patients were included from the discovery cohort and 47 patients were included from a second validation cohort. All patients had a definite ARVC diagnosis at time of blood withdrawal. sST2, Gal-3 and GDF-15 were independently correlated with NT-proBNP, left ventricular (LV) ejection fraction, late gadolinium enhancement by cardiac magnetic resonance (CMR) imaging and clinical outcome.

Results

ARVC patients with LV involvement had higher levels of sST2 and GDF-15 as compared to controls and patients with isolated right ventricular involvement. sST2 and GDF-15 significantly correlated to late gadolinium enhancement on CMR and also correlated to adverse heart failure outcomes. Gal-3 was elevated in ARVC patients with and without LV involvement as compared to controls. The combined use of the three biomarkers (NT-proBNP, sST2 and GDF-15) showed the best performance in predicting LV involvement in both the discovery and the validation cohort. Plasma drawn from coronary arteries and coronary sinus showed a transmyocardial elevation of sST2.

Conclusion

Our study shows that sST2 and GDF-15 may predict BiV involvement and the combined use of NT-proBNP, sST2 and GDF-15 shows the best prediction of LV involvement in ARVC. Transmyocardial elevation of sST2 suggests that this biomarker is produced by myocardial tissue in ARVC.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Fuwai ARVC Program was supported by CAMS Innovation Fund for Medical Sciences and the National Natural Science Foundation of China, Zurich ARVC Program was supported by grants from the Schwyzer Foundation and Baugarten Foundation

Multiple clinical profiles of families with the short QT syndrome

Aims

Short QT syndrome (SQTS) is a rare cardiac channelopathy characterized by a shortened corrected QT (QTc)-interval that can lead to ventricular arrhythmias and sudden cardiac death. The aim of this study was to investigate the clinical phenotypes and long-term outcomes of three families harbouring genetic mutations associated with the SQTS.

Methods and results

Clinical data included medical history, physical examination, 12-lead ECG, 24-h Holter-ECG, and transthoracic echocardiography from three index patients and their first-degree relatives. Next generation clinical exome sequencing and genetic cascade screening were performed in index patients and their relatives, respectively. Two index patients experienced malignant ventricular arrhythmias and one patient suffered from arrhythmogenic syncope during a median follow-up period of 8 years. They all had genetic mutations associated with the SQTS. Two mutations were found in the KCNH2 gene, and one in the CACNA2D gene. One patient had an additional SCN10A variant. Alive and mutation-positive family members had short QTc-intervals, but no further phenotypic manifestations. None of the mutation-negative family members had an abnormal ECG or any symptoms. In all patients with shortened QTc-intervals, the QTc-interval had a low long-term variability and QTc shortening always remained detectable by 12-lead ECG.

Conclusion

This study shows the variety of phenotypic manifestations in different families with SQTS. It further emphasizes the importance of a 12-lead ECG for early diagnosis, and the utility of next generation sequencing for the identification of mutations associated with the SQTS.