“Concealed cardiomyopathy” is an important cause of autopsy-inconclusive sudden cardiac death and diagnosis impacts care of surviving relatives

Background

Genetic testing following sudden cardiac death (SCD) is currently guided by autopsy findings, despite the inherent challenges of autopsy examination and mounting evidence that malignant arrhythmia may occur prior to structural changes in inherited cardiomyopathy, so-called “concealed cardiomyopathy” (CCM).

Purpose

To identify the spectrum of genes implicated in autopsy-inconclusive SCD and describe the importance of identifying CCM for the ongoing care of SCD families.

Methods

Using a standardised framework for adjudication, autopsy-inconclusive SCD cases were identified as having a structurally normal heart or sub-diagnostic findings of uncertain significance on autopsy. Genetic variants were classified for pathogenicity using the American College of Medical Genetics and Genomics guidelines. Family follow-up was performed where possible.

Results

Twenty disease-causing variants were identified among 91 autopsy-inconclusive SCD cases (mean age 25.4±10.7 years) with a similar rate regardless of the presence or absence of sub-diagnostic findings (25.5% vs 18.2%, p=0.40). Cardiomyopathy-associated genes harboured 70% of clinically-actionable variants and were overrepresented in cases with sub-diagnostic structural changes at autopsy, accounting for 11 out of 12 disease-causing variants in this group (79% vs 21%, p=0.038, Figure 1, panel A). Variants in arrhythmogenic cardiomyopathy genes were the most common cause of CCM (9/14 CCM cases, Figure 1, panel B). Nearly two-thirds of genotype-positive relatives had an observable phenotype either on initial assessment or during subsequent follow-up. Twenty-seven genotype-negative first-degree relatives were released from ongoing screening.

Conclusion

The current paradigm of phenotype-directed genetic testing following SCD risks under recognition of CCM. Comprehensive evaluation of the decedent should include assessment of genes implicated in both cardiomyopathy and primary arrhythmias to improve diagnosis of CCM and optimise care for families.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Heart Foundation of Australia and National Health and Medical Research CouncilNew South Wales Health

Using co-design to develop an online intervention for families after a sudden cardiac death in the young

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): National Heart Foundation of Australia / NHMRC Co-funded Post Graduate Scholarship

Introduction

Sudden cardiac death (SCD) is a devastating complication of many genetic heart diseases. The psychological impact on surviving family members is significant and lifelong. Previous needs analysis found medical and psychological needs are of high importance but remain unmet in some cases. Co-design is an increasingly popular research method for the development of interventions and services that include users as contributing members of the research team. Previous research has shown co-design leads to innovative ideas that better address user needs.

Purpose

To use co-design to develop an online support intervention for families after SCD.

Methods

Semi-structured moderated online focus groups were held with key stakeholders, including family members who had experienced young SCD, healthcare professionals and researchers. Guided discussions were used to co-design an online support intervention. Thematic analysis of discussions and iterative feedback on draft materials guided content development.

Results

Four focus groups were held (average 11 participants per group). Stakeholder involvement facilitated development of high-level ideas and priority issues. Key benefits included creative content and materials developed based on user preference for stories, narratives and information reflecting everyday experience of families navigating the legal and medical processes surrounding SCD, normalising and supporting grief responses in the context of family relationships, and fostering hope.

Conclusion

Co-design supported creative presentation, tailoring of information and development of psychosocial interventions to meet the needs of SCD families. Further work is needed to pilot and trial the intervention, prior to it becoming a key resource in the care of these families.

A prospective longitudinal study of health-related quality of life and psychological wellbeing after an implantable cardioverter defibrillator in patients with genetic heart diseases

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): NHMRC Project Grant National Heart Foundation Future Leader Fellowship

OnBehalf

Cardio Genomics Program

Introduction

Genetic heart diseases, often affecting young people, can be clinically heterogeneous and pose an increased risk of sudden cardiac death (SCD). The implantable cardioverter defibrillator (ICD) is a lifesaving therapy. Impact on prospective and long-term psychological and health-related quality of life (HR-QoL) after ICD implant in patients with genetic heart diseases is unknown.

Purpose

We aimed to investigate the psychological functioning and HR-QoL over time in patients with genetic heart diseases who receive an ICD and to identify risk factors for poor psychological functioning and HR-QoL.

Methods

A prospective longitudinal design was used. Patients diagnosed with a genetic heart disease for which they received an ICD, were eligible. Anxiety, depression, health-related quality of life and device acceptance were measured using validated questionnaires. Baseline surveys were completed prior to ICD implantation with five-year follow-up after ICD implant.

Results

Forty patients with an inherited cardiomyopathy or arrhythmia syndrome (mean age 46.3 ± 14.2 years; 65.0% males) were included. Mean psychological and HR-QoL measures were within normative ranges during follow-up. We observed significant overall improvements from baseline to first follow-up with variability increasing after 36 months. The presence of comorbidities predicted worse physical HR-QoL (p = 0.014). Other predictors were not statistically significant, although lower education and female gender seemed to be an interesting predictor for higher anxiety and less mental HR-QoL, and the presence of comorbidities for less physical HR-QoL.

Conclusion

While the majority of patients with a genetic heart disease adjust well to their ICD implant, a subset of patients experiences poor psychological and HR-QoL outcomes.

Initiation of heterotopic osteogenesis in primates after chromatographic adsorption of osteogenin, a bone morphogenetic protein, onto porous hydroxyapatite

The chromatographic adsorption of partially purified osteogenin, a bone morphogenetic protein (BMP), onto porous hydroxyapatites for the construction of an osteogenic delivery system was investigated. Osteogenin fractions, with osteogenic activity in rats, were chromatographically adsorbed onto porous hydroxyapatites and implanted intramuscularly in baboons (Papio ursinus). Histology showed extensive bone differentiation within the porous spaces as early as 30 days after implantation in baboons. The unbound eluate from the porous hydroxyapatites showed lack of osteogenic activity when bioassayed in rats. These findings in primates may help to construct custom made porous ceramic as carriers for BMPs resulting in predictable bone formation for treatment of human bone defects.

Reconstruction of the bone--bone marrow organ by osteogenin, a bone morphogenetic protein, and demineralized bone matrix in calvarial defects of adult primates

Information concerning the efficacy of osteogenin, a bone morphogenetic protein, and demineralized bone matrix in orthotopic sites in nonhuman primates is a prerequisite for potential clinical application in humans. After exposure of the calvaria, 84 cranial defects, 25 mm in diameter, were prepared in 26 adult male baboons (Papio ursinus). Defects were implanted with insoluble collagenous bone matrix (ICBM, the inactive collagenous residue after dissociative extraction of bone matrix with 4 M guanidine hydrochloride) reconstituted with osteogenin fractions isolated from baboon bone matrix by chromatography on heparin-Sepharose and hydroxyapatite-Ultrogel (Og Hep-HA) or osteogenin further purified using Sephacryl S-200 gel filtration chromatography (Og S-200). Baboon osteogenin with the highest biologic activity in a rodent bioassay, as determined by alkaline phosphatase activity, calcium content, and histologic analysis, was used for orthotopic implantation in baboons. Additional defects were implanted with baboon demineralized bone matrix (DBM) or ICBM without osteogenin as control. Defects also were grafted with corticocancellous bone harvested from the iliac crest or left ungrafted to monitor the spontaneous regeneration potential of the adult baboon calvaria. Undecalcified bone sections at 7 microns were prepared from the harvested specimens 30 and 90 days after surgery. Histomorphometry demonstrated that Og S-200 induced copious amounts of bone and osteoid as early as day 30 (P < 0.01 versus ICBM, autogenous grafts and untreated defects). At day 90, in implants of Og S-200, Og Hep-HA, and DBM, bone and marrow formation was extensive, culminating in complete regeneration of the craniotomies. In implants of DBM, bone formed with an intervening phase of cartilage development. This provides the phenotypic evidence of endochondral bone differentiation by induction in defects of membranous calvarial bone in adult primates. These results establish the potential therapeutic application of osteogenin and demineralized bone matrix for the architectural reconstruction of the bone-bone marrow organ in humans.

Initiation of bone regeneration in adult baboons by osteogenin, a bone morphogenetic protein

Osteogenin, and related bone morphogenetic proteins, induce endochondral bone differentiation through a cascade of events which include formation of cartilage, hypertrophy and calcification of the cartilage, vascular invasion, differentiation of osteoblasts, and formation of bone. These events have been studied in a postnatal model of bone development in rodents. Information concerning the morphogenetic potential of osteogenin in primates is a prerequisite for potential clinical application in man. The efficacy of allogeneic osteogenin in primates was investigated in both extraskeletal and skeletal sites in 19-Chacma baboons (Papio ursinus). Osteogenin was isolated from demineralized baboon bone matrix and purified by chromatography on heparin-Sepharose, hydroxyapatite, and Sephacryl S-200. Protein fractions with a molecular mass range of 26-42 kDa induced cartilage and bone differentiation in the subcutaneous space of rats. Final purification to homogeneity was obtained by electroendosmotic elution from a preparative sodium dodecyl sulphate (SDS) polyacrylamide gel, resulting in a single band on a SDS-polyacrylamide gel with an apparent molecular mass of 30-34 kDa, with biological activity in rats. The osteoinductive potential of osteogenin in primates was tested first in intramuscular sites in baboons and found to be active. The bone regeneration potential was investigated in nonhealing calvarial defects surgically prepared in adult male baboons. Baboon osteogenin induced complete regeneration of the cranial wound. These findings in adult primates establish a primary role for osteogenin in initiation and promotion of osteogenesis, and imply a potential therapeutic application based on cell biology of extracellular matrix-cell interactions.