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Atrial fibrillation more likely with low-carb diet
NEW ORLEANS — A diet low in carbohydrates may lead to a greater risk for atrial fibrillation, according to findings presented at the American College of Cardiology Scientific Session.
Xiaodong Zhuang, MD, PhD, a cardiologist at the First Affiliated Hospital of Sun Yat-Sen University in Guangzhou, China, and colleagues sought to identify the association between carbohydrate intake proportion and the risk for incident AF in the ARIC study.
“Our team has conducted long-term epidemiological, clinical and basic research on cardiovascular disease. The relationship between diet and cardiovascular disease is one of our research directions, which has important clinical guiding significance,” Zhuang told Cardiology Today.
The researchers confirmed AF from ECG, hospital discharge codes and death certificates.
Zhuang and colleagues analyzed 13,852 participants (mean age, 54 years; 45% men). Mean carbohydrate intake proportion was 48.8%.
During a median follow-up of 22 years, 1,892 cases of AF occurred, the researchers wrote.
Zhuang and colleagues found that compared with the lowest tertile of carbohydrate intake, the second tertile (HR = 0.82; 95 CI%, 0.73-0.93) and the third tertile (HR = 0.84; 95% CI, 0.71-0.99) had reduced risk for incident AF.
The researchers identified a U-shaped relationship between carbohydrate intake and risk for AF incidence (P < .005) in spline regression, with the lowest observed risk associated with carbohydrate intake proportion of 39% to 61%.
“Low-carbohydrate diets were associated with increased risk of AF, regardless of the replacement type of protein or fat,” Zhuang said in an interview. “Our findings suggested that this popular weight control method by restricting carbohydrate intake should be recommended cautiously.” – by Earl Holland Jr.
Reference:
Zhuang X, et al. Abstract 1123-310. Presented at: American College of Cardiology Scientific Session; March 16-18, 2019; New Orleans.
Disclosure: Zhuang reports no relevant financial disclosures.
Perspective
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The study is intriguing because we need to better identify potentially modifiable risk factors for AF.
There’s not enough strong evidence to inform us about how to prevent AF, and there’s not previously been a lot of research examining diet and AF.
I think, in some ways, it’s straightforward.
There are a few important limitations to bear in mind as we think about the implications of these results. For example, it doesn’t appear they adjusted for any other covariates. Specifically, there was no apparent multivariable adjustment for demographics, other medical conditions, or other behaviors of the research participants.
It remains possible that the dietary pattern that they identified as associated with AF does not actually have a causal relationship, but rather travels with some other characteristic or behavior that itself is responsible for the heightened AF risk.
In fact, that it is an observational study and not a randomized trial means the findings should be considered hypothesis-generating rather than something we can rely on for causal inference. We shouldn’t necessarily assume causality when we see this sort of association.
There’s a lot of interest in randomized trials of diet, which are difficult to conduct because it’s difficult to enforce an assigned diet given the broad accessibility of food options.
Our good fortune, especially in wealthy nations, is that most people have access to sufficient nutrition, and, in fact, a pretty broad choice of the things they eat.
But that leads to challenges in conducting that sort of research.
The ideal study would be a randomized trial. From an efficiency standpoint, it’s also possible that one could tack on such an analysis to the randomized trial of diet that was being pursued for other reasons.
The cohort used for this particular study, ARIC, has been one of the few cohorts that have been extremely valuable to provide this sort of research.
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