A systematic review on adherence to continuous positive airway pressure (CPAP) treatment for obstructive sleep apnoea (OSA) in individuals with mild cognitive impairment and Alzheimer's disease dementia

Obstructive sleep apnoea (OSA) is highly prevalent in mild cognitive impairment (MCI) and Alzheimer's disease (AD). The gold standard treatment for OSA is continuous positive airway pressure (CPAP). Long-term, well-powered efficacy trials are required to understand whether CPAP could slow cognitive decline in individuals with MCI/AD, but its tolerability in this group remains uncertain. The present review investigates CPAP adherence among individuals with OSA and MCI/AD. Electronic searches were performed on 8 databases. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Six independent studies and four secondary analyses included 278 unique participants (mean age = 72.1 years). In five of the retained studies, around half of participants (45% N = 85 MCI, 56% N = 22 AD) were adherent to CPAP, where ≥4 h use per night was considered adherent. Three of the retained studies also reported average CPAP use to range between 3.2 and 6.3 h/night. CPAP adherence in individuals with MCI and AD is low, albeit similar to the general elderly population. Reporting adherence in future studies as both average duration as well as using a binary cut-off would improve our understanding of the optimum CPAP use in dementia clinical trials and care.

Sex disaggregated analysis of risk factors for adverse outcomes in hypertrophic cardiomyopathy

Background

Patient sex has been associated with differences in disease penetrance and clinical expression in HCM. We sought to investigate sex-disaggregated differences in risk factors for adverse outcomes in a large international HCM registry.

Methods

This is a retrospective study of HCM patients from the Sarcomeric Human Cardiomyopathy Registry. Cox proportional hazards models were fit with a sex interaction term to determine significant differences between sexes.

Results

6647 (38% women) probands with HCM were included. After a mean follow-up of 6.4 years from first encounter, women had a higher risk of heart failure (HF) composite (HR 1.77; 95% CI 1.56–1.99, p<0.0001), and death (1.22; 1.03–1.45, p=0.02) compared to men. No sex difference existed for ventricular arrhythmia composite (p=0.2) or atrial fibrillation (p=0.6). Sarcomere positive status (Sarc+) and causative variants in MYBPC3 reduced the risk of the HF composite for women, while for men there was no change in risk (P-heterogeneity=0.016 and <0.0001, respectively). Baseline LVEF <35% and larger LA size increased the risk of the HF composite for both sexes but to a greater magnitude in men (P-heterogeneity=0.0003 and 0.04 respectively) (Figure 1). Sarc+ increased the risk of death in men but not women (P-heterogeneity=0.041). Having the HF composite increased the risk of death by 45% in and 240% in men (P-heterogeneity=0.003) (Figure 2).

Conclusion

There are important sex differences in the risk of heart failure and death in those with HCM, with significant heterogeneity of outcomes based on subgroups defined by genetic and imaging factors.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): The Sarcomeric Human Cardiomyopathy Registry (SHaRe) is supported by an unrestricted research grant from Bristol Myer Squibb, including funds to individual sites for database support.

“Concealed cardiomyopathy” as a cause of previously unexplained sudden cardiac arrest

Background

Current genetic testing guidelines recommend against broad, multi-phenotype genetic testing in survivors of sudden cardiac arrest (SCA) where no cause is identified on clinical screening. Recent reports describe malignant arrhythmic events preceding detectable structural changes in patients with pathogenic variants in cardiomyopathy genes, who go on to demonstrate structural changes in follow up.

Purpose

We sought to investigate the utility of a broad genetic testing approach, sequencing genes implicated in both arrhythmia syndromes and cardiomyopathy, in SCA survivors where no cause was identified after thorough clinical evaluation.

Methods

We retrospectively reviewed the clinical and genetic profiles of SCA survivors referred to a specialised genetic heart disease multidisciplinary team in Australia. Multi-phenotype genetic testing included analysis of 174 cardiac genes associated with arrhythmia or cardiomyopathy.

Results

The cohort was comprised of 86 SCA survivors. A clinical diagnosis was made in 46 (53%) patients while 40 (47%) cases were considered idiopathic, with no cause of arrest identified despite thorough clinical investigation. Thirty-two survivors of idiopathic SCA (80%) underwent broad, multi-phenotype genetic testing through genome (n=1), exome (n=26) or extended panel (n=5) analysis. The majority of the cohort were male (62.5%, n=25) and ≤35 years of age at time of arrest (60%, n=24). Events in this group most commonly occurred at rest or sleep (65.8%, n=25) and 5 patients had a family history of sudden death (12.5%).

Seven disease causing variants were identified with a testing yield of 21.9%. There was no difference in demographic or clinical factors between those with and without a disease-causing variant.

Six (85.7%) of these clinically actionable variants were identified in genes associated with cardiomyopathy (PKP2, MYBPC3, DES, DSP and ACTN2) that would not have been analysed on a standard commercial cardiac arrhythmia panel. Cardiac magnetic resonance (CMR) imaging was performed prior to genetic testing in 4 of the 6 cases found to have disease-causing variants in cardiomyopathy genes (2 patients did not have CMR performed due to the presence of cardiac devices), with 2 (50%) showing sub-diagnostic changes while 2 (50%) revealed a structurally normal heart.

Conclusion

A broad approach to genetic testing in idiopathic SCA can improve care for patients and their families by identifying clinically actionable variants that would be missed by phenotype specific gene panels and thus significantly increase the rate of diagnosis. “Concealed cardiomyopathy” represents a clinical challenge in how to manage patients and their relatives who carry a pathogenic cardiomyopathy variant, have no overt signs of structural disease, yet have an important risk of sudden cardiac arrest.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Cardiac Society of Australia and New Zealand; National Health and Medical Research Council (Australia)