More research on the reported interracial disparity among patients undergoing transcatheter aortic valve replacement (TAVR) could improve risk stratification and aid the development of novel TAVR approaches, an expert said.
“The TAVR field is expanding rapidly in the Asia-Pacific in tandem with rising life expectancy, but studies have identified interracial differences in the clinical, anatomic and procedural characteristics of TAVR patients,” Duk-Woo Park, MD, PhD (Asan Medical Center, Seoul, Korea (Republic of)) said at the 27th TCTAP 2022 on Apr 28.
“These studies observed differences in clinical outcomes arising from heterogeneous features, although findings reassuringly showed no significant differences in clinical outcomes,” Park said. “In Asia, specific population- and healthcare system-related TAVR challenges suggest future research on ethnic disparities may optimize TAVR outcomes.”
The number of TAVR procedures performed annually for AS patients have increased significantly worldwide after multiple studies proved the procedure to be a safe and effective alternative to surgical aortic valve replacement (SAVR).
Several US-based studies have since reported racial disparities associated with TAVR, including differences in rates of aortic valve replacement (AVR), procedural complications, and disease burden.
Although the studies found differences in baseline characteristics by Caucasian, African-American or Hispanic populations, adjusted outcomes at 30-days and 1-year were comparable between groups.
Findings also showed that underrepresented racial and ethnic groups (UREGs) relative to white patients were at higher risk for AS and AS factors but ironically had a lower disease burden in a phenomenon called the “AS paradox,” Park said.
The studies also found the AS paradox in black and other non-white patients with severe symptomatic AS that showed lower disease incidence and prevalence.
Results further reported that UREGs were less likely to receive either SAVR or TAVR compared to white patients and likely to have similar or worse short- and long-term outcomes.
Park noted that Asian patients were underrepresented in studies, accounting for less than 3 percent. Most TAVR trials were also conducted in the US and Europe, where regional and regulatory issues related to TAVR differ from Asian countries.
“TAVR adoption has lagged in Asian countries due to high device cost, limited health and reimbursement policies, lack of specific training programs, and specialized heart teams and infrastructure,” Park said. “Availability and price of TAVR devices also differ by country and serve as additional challenges.”
A series of Korean studies co-authored by Park and colleagues showed clinical, anatomical and procedural differences between Asian and non-Asian TAVR patients, although procedural complications and clinical outcomes remained similar.
Notably, the research team found that Asian patients had lower body mass index (BMI), smaller annulus area, smaller device size and more bicuspid aortic valves compared to non-Asian patients.
The multinational, multicenter, multiethnic TP-TAVR Registry study published in the BMJ Heart last February further revealed baseline differences between Asian and non-Asian TAVR patients (Asian: 581 vs. Non-Asian: 831) at three medical institutions worldwide.
Analysis of 1,412 patients enrolled at Asan Medical Center (Seoul, Korea (Republic of); n=536), Northwestern Memorial Hospital (Illinois, USA; n=398) and Stanford Health Care-Hospital (California, USA; n=478) showed Asian patients had significantly lower BMI (24 vs. 28.4, p<0.001) and STS scores (4.16 vs. 5.66, p<0.001) than non-Asian patients.
Asian patients also had lower rates of atrial fibrillation (12.4% vs. 39.8%, p<0.001) and peripheral vascular disease (3.8% vs. 24.7%, p<0.001). Echocardiography and CT findings showed Asian patients had smaller aortic valve areas (0.62 cm2 vs. 0.72 cm2, p<0.001) and more bicuspid aortic valves (10% vs. 3.9%, p<0.001).
For procedural characteristics, a bigger prosthesis size was less common in Asians (p=0.01) and Asian patients had higher rates of life-threatening or disabling bleeding complications (4.5% vs. 1.2%, p<0.001) and major vascular complications (4.1% vs. 1.7%, p=0.009).
For outcomes, the rate of 1-year primary composite outcome encompassing all-cause mortality, stroke, rehospitalization initially seemed lower in Asians (26% vs. 35%, HR 0.73, 95% CI 0.59-0.89, p=0.003), but multivariable adjustment showed no significant difference between the two groups (HR 0.79, 0.60-1.03, P=0.08).
“Adjustment for various clinical variables showed low rates of all-cause mortality and primary composite outcome in both Asian and non-Asian populations with no statistical difference,” Park said. “The findings held even with substantial differences in baseline demographic, clinical and anatomical characteristics.”
“These results indicate that the observed interracial differences in clinical outcomes are largely explained by baseline differences in clinical, anatomical and procedural factors,” Park said, noting that understanding differences could help minimize the risk of prosthesis-patient mismatch (PPM).
PPM may be particularly relevant for Asian populations that generally have unique anatomical features such as smaller annular dimension and valve implant size compared to Western populations, Park said.
A previous study showed PPM incidence was lower in Asian populations (7.1% vs. 24.7%), although it had no significant prognostic impact for 1-year composite outcomes of all-cause mortality, stroke or rehospitalization.
“Overall, there were substantial interracial differences in clinical, anatomic, and procedural characteristics in TAVR patients,” Park said. “Future research into racial disparities can help optimize TAVR procedures for countries in the Asia-Pacific region.”
Edited by
Sang-Cheol Cho , MD
Yeosu Jeil Hospital, Korea (Republic of)
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