Cocoa flavanol supplementation may reduce incident atrial fibrillation over time
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Key takeaways:
- Participants who took cocoa extract supplements had a significant reduction in incident AF after 5.5 years.
- The properties of cocoa flavanols may lead to atrial remodeling, which protects against incident AF.
Cocoa flavanols may reduce the risk for incident atrial fibrillation over time, perhaps as a result of atrial remodeling, according to a secondary analysis of a completed study published in European Journal of Preventative Cardiology.
Although several large-scale, long-term cohort studies have analyzed the relationship between cocoa flavanols and cardiovascular health, information is lacking concerning the association between AF and cocoa flavanols, according to researchers.
This motivated Melissa E. Middeldorp, PhD, MPH, postdoctoral researcher in the department of cardiology at University Medical Centre Groningen, the Netherlands, and colleagues to conduct a secondary analysis of the COSMOS study to specifically look at AF as an outcome.
The original COSMOS trial involved 21,422 U.S. adults to determine whether taking 500 mg of flavanol supplements or a multivitamin can help to prevent cardiovascular disease and cancer. As Healio previously reported, results showed participants who were randomly assigned to receive the cocoa flavanol supplement had a 27% lower risk for CV death than those assigned placebo.
Of the total COSMO participants, 18,188 individuals who did not have a history of irregular heart rhythm at baseline and who completed a semi-annual questionnaire about new physician diagnoses of AF were included in the secondary analysis.
Middeldorp and colleagues found that over a median follow-up of 5.5 years, 1,029 participants (5.7%) reported being diagnosed with incident AF. Of these cases, 694 occurred during a median of 3.5 years of randomized treatment — including 333 in the cocoa extract group and 361 in the placebo group —and 335 occurred during the median 2 years of after intervention follow-up, including 144 in the extract group and 191 in the placebo group.
Using Cox proportional hazards models, results showed that although incident AF did not significantly differ between the cocoa extract and placebo groups during the intervention phase (HR = 0.92; 95% CI, 0.79-1.06; P = .24), there was a significant reduction after 5.5 years of cumulative follow-up (HR = 0.85; 95% CI, 0.75-0.96; P = .01).
Further, the researchers found that participants who were taking the cocoa extract supplement had a significant reduction in incident AF compared to placebo in the phase following the intervention (HR = 0.75; 95% CI, 0.6-0.93).
Limitations included that AF was not a predefined endpoint of the COSMOS trial and that incident AF events were self-reported and may have potentially biased results toward the null, the researchers wrote.
Middeldorp and colleagues theorized that the vasodilatory, anti-inflammatory, antioxidant, antiplatelet and angiotensin-converting enzyme properties of cocoa flavanols may result in “electrical and structural atrial remodeling, which are potentially protective against AF development.” This would also explain why the reduction of incident AF events only became apparent after the extended follow-up of 5.5 years, by which point atrial remodeling may have occurred.
“Based upon these promising trial results, the hypothesis that cocoa flavanols may reduce the risk of incident AF warrants further study in future randomized trials,” Middeldorp and colleague wrote.
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