Regional differences in aortic valve replacements: Atlantic Canadian experience

Challenges in Promoting Health Equity and Reducing Disparities in Access Across New and Established Technologies

Medical innovations and novel technologies stand to improve the return on high levels of health spending in developed countries, particularly in cardiovascular care. However, cardiac innovations also disrupt the landscape of accessing care, potentially creating disparities in who has access to novel and extant technologies. These disparities might disproportionately harm vulnerable groups, including those whose nonmedical conditions-including social determinants of health-inhibit timely access to diagnoses, referrals, and interventions. We first document the barriers to access novel and existing technologies in isolation, then proceed to document their interaction. Novel cardiac technologies might affect existing available services, and change the landscape of care for vulnerable patient groups who seek access to cardiology services. There is a clear need to identify and heed lessons learned from the dissemination of past innovations in the development, funding, and dissemination of future medical technologies to promote equitable access to cardiovascular care. We conclude by highlighting and synthesizing several policy implications from recent literature.

Relationship of Neighbourhood Social Deprivation and Ethnicity on Access to Transcatheter and Surgical Aortic Valve Replacement: A Population-Level Study

BACKGROUND

Wide geographic variation in access to transcatheter (TAVR) and surgical (SAVR) aortic valve replacement exists, but the impact of socioethnic factors on the geographic variation of AS management in Ontario, Canada, is unknown.

METHODS

Neighbourhood rates of AS admissions, as a proxy for AS burden, and downstream TAVR and SAVR referrals and procedures were estimated for the 76 subregions in Ontario. To determine if the socioethnic geographic variations in referrals and procedures were concordant or discordant with AS burden, we calculated Pearson correlation coefficients to determine the relationship between AS burden and each of TAVR referrals, TAVR procedures, SAVR referrals, or SAVR procedures. We developed generalised linear models to determine the association between social deprivation indices captured in the Ontario Marginalization index and the rates of AS burden as well as TAVR/SAVR referral and procedures.

RESULTS

There was wide geographic variation that was concordant between AS burden and the referral and procedure rates for TAVR and SAVR (correlation coefficients 0.86-0.96). Increased dependency was associated with higher rates of both TAVR/SAVR referrals and procedures (rate ratios 1.63-2.22). Neighbourhoods with a higher concentration of ethnic minorities were associated with lower AS burden as well as lower rates of both SAVR and TAVR referrals and procedures (rate ratios 0.57-0.85).

CONCLUSIONS

An important ethnic gradient exists in AS burden and in both referral and completion of TAVR and SAVR in Ontario. Further research is necessary to understand if this gradient is appropriate or requires mitigation.

Drivers and outcomes of variation in surgical versus transcatheter aortic valve replacement in Ontario, Canada: a population-based study

Objectives

To understand the patient and hospital level drivers of the variation in surgical versus trascatheter aortic valve replacement (SAVR vs TAVR) for patients with aortic stenosis (AS) and to explore whether this variation translates into differences in clinical outcomes.

Background

Adoption of TAVR has grown exponentially worldwide. Notwithstanding, a wide variation in TAVR rates has been seen within and between countries and in some jurisdictions AS is still primarily being managed by SAVR.

Methods

We conducted a population-based retrospective cohort study in Ontario, Canada, including individuals who received TAVR or SAVR between 2016 and 2020. We developed iterative hierarchical logistic regression models for the likelihood of receiving TAVR instead of SAVR examining sequentially patient characteristics, hospital factors and year of procedure, calculating the median ORs and variance partition coefficients for each. Using Cox proportional hazards models, we examined the relationship between TAVR/SAVR ratio on all-cause mortality and readmissions.

Results

Annual procedures rates per million population increased from 171 to 201, mainly driven by the expansion of TAVR. TAVR/SAVR ratios differed substantially between hospitals, from 0.21 to 3.27. Neither patient nor hospital factors explained the between-hospital variation in AS treatment. The TAVR/SAVR ratio was significantly associated with clinical outcomes with high ratio hospitals having lower mortality and rehospitalisations.

Conclusions

Despite the expansion of TAVR, dramatic variation exists that is not explained by patient or hospital factors. This variation was associated with differences in clinical outcomes, suggesting that further work is needed in understanding and addressing inequity of access.

Calcific aortic valve disease: from molecular and cellular mechanisms to medical therapy

Calcific aortic valve disease (CAVD) is a highly prevalent condition that comprises a disease continuum, ranging from microscopic changes to profound fibro-calcific leaflet remodelling, culminating in aortic stenosis, heart failure, and ultimately premature death. Traditional risk factors, such as hypercholesterolaemia and (systolic) hypertension, are shared among atherosclerotic cardiovascular disease and CAVD, yet the molecular and cellular mechanisms differ markedly. Statin-induced low-density lipoprotein cholesterol lowering, a remedy highly effective for secondary prevention of atherosclerotic cardiovascular disease, consistently failed to impact CAVD progression or to improve patient outcomes. However, recently completed phase II trials provide hope that pharmaceutical tactics directed at other targets implicated in CAVD pathogenesis offer an avenue to alter the course of the disease non-invasively. Herein, we delineate key players of CAVD pathobiology, outline mechanisms that entail compromised endothelial barrier function, and promote lipid homing, immune-cell infiltration, and deranged phospho-calcium metabolism that collectively perpetuate a pro-inflammatory/pro-osteogenic milieu in which valvular interstitial cells increasingly adopt myofibro-/osteoblast-like properties, thereby fostering fibro-calcific leaflet remodelling and eventually resulting in left ventricular outflow obstruction. We provide a glimpse into the most promising targets on the horizon, including lipoprotein(a), mineral-binding matrix Gla protein, soluble guanylate cyclase, dipeptidyl peptidase-4 as well as candidates involved in regulating phospho-calcium metabolism and valvular angiotensin II synthesis and ultimately discuss their potential for a future therapy of this insidious disease.