The benefit of ablation seen in minorities - but not in nonminorities - seems to be due to worse outcomes with drug therapy, and there are multiple reasons for that, Dr. Kevin Thomas of Duke University Research Center in Durham, North Carolina told Reuters Health by email. One reason, he said, is "non-concordant guideline use of anti-arrhythmic drugs (AADs), (which) may cause adverse outcomes."
In a study released online in January, he noted, a multivariate model showed that "Black race and Hispanic ethnicity were not associated with guideline-concordant AAD use and Asian race was." (https://bit.ly/3jOWKrP)
Further, he noted, "Black individuals have a higher prevalence of left ventricular hypertrophy, heart failure and renal insufficiency - known characteristics that influence the selection of AADs and increase the risk of drug toxicity and proarrhythmia."
"Another hypothesis," he added, "is that persistence/adherence to AAD therapy may be difficult due to social determinants of health, including costs associated with drugs; difficulty complying with twice-daily schedules due to work or other environmental conditions; and the inability to access long-term follow up with clinicians who are comfortable prescribing these drugs and attaining the necessary laboratory and EKG testing to ensure safe continuation."
For the secondary analysis of the CABANA trial, reported this week in the Journal of the American College of Cardiology, Dr. Thomas and colleagues analyzed data on 1,280 participants with AF randomized to receive ablation or drug therapy.
Only participants in North America were included, and they were subgrouped as racial/ethnic minority or nonminority using U.S. National Institutes of Health definitions. The primary endpoint was a composite of death, disabling stroke, serious bleeding, or cardiac arrest.
One hundred and twenty-seven participants (9.9%) were racial and ethnic minorities. They were younger than nonminorities (median age, 65.6 vs. 68.5) and had more symptomatic heart failure (37% vs. 22%), hypertension (92.1% vs. 76.8%), and ejection fraction <40% (20.8% vs. 7.1%).
Racial/ethnic minorities treated with ablation had a 68% relative reduction in the primary endpoint (adjusted hazard ratio, 0.32) and a 72% relative reduction in all-cause mortality (aHR, 0.28).
Primary event rates for both groups were similar for ablation (4-year Kaplan-Meier event rates 12.3% vs. 9.9%) but not for drug therapy: racial and ethnic minorities on drug therapy had a much higher event rate than nonminority participants (27.4% vs. 9.4%).
Dr. Thomas said, "Prior studies have suggested that Black and Hispanic individuals are less likely to be referred or have access to cardiologists and cardiac electrophysiologists. Improving access/referral to proceduralists who perform catheter ablation and educating patients and clinicians about the potential benefits of catheter ablation for AF in racial and ethnic minorities are feasible and paramount."
Dr. Andrea Russo of the Cooper Medical School of Rowan University in Camden, New Jersey, author of a related editorial, commented in an email to Reuters Health, "These findings highlight the importance of enrolling a racially and ethnically diverse group of subjects in clinical trials, because outcomes may not necessarily be generalizable to all subgroups."
"We also need to do better with assuring that we offer all patients, regardless of race, ethnicity or sex, comprehensive options for the treatment of AF," she said. "Gaining a better understanding of racial differences in treatment of AF and their relationship to outcomes is essential for developing comprehensive practice guidelines that everyone can follow and for eliminating racial disparities in the treatment of underrepresented populations."
"This paper should be a 'call to action' to ensure that all treatment options, including catheter ablation, are widely accessible to provide the highest quality of care for all patients with AF," she concluded.
Dr. Muhammad Afzal, an electrophysiologist at The Ohio State University Wexner Medical Center in Columbus, also commented by email. "The current study suggests a lower enrollment of patients from ethnic minorities in CABANA," he said. "Although ethnic minorities make over 30% of the U.S. population, only 10% of these patients participated in this landmark trial."
"System-wide approaches to promote education regarding the differences in enrollment, outcomes and access to advanced healthcare for minority patients would minimize this discrepancy over time," Dr. Afzal said.
SOURCE: https://bit.ly/2TBpRV0 Journal of the American College of Cardiology, online July 5, 2021.
By Marilynn Larkin
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