Restricting salt in patients with high intake could be effective for AF prevention
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Key takeaways:
- Salt restriction in patients at high atrial fibrillation risk with high sodium intake may lower risk for incident AF.
- Lowest AF risk was observed at 6 g of sodium per day, but the threshold may be even lower.
Salt reduction in patients who have high daily sodium intake and are at high risk for atrial fibrillation may lower risk for incident AF, according to a study published in JAMA Network Open.
“In patients with established AF, systolic BP is associated with stroke risk. As clinical trials have shown that reducing sodium intake can reduce BP, sodium intake is a logical target to prevent AF, stroke, and cardiac mortality,” Linda S. Johnson, MD, PhD, an associate professor in the department of clinical sciences at Lund University in Sweden, and colleagues wrote. “The association between sodium intake and AF has not been extensively studied. We aimed to study the association between estimated sodium intake (from a fasting morning urine sample) and incident AF in a high-risk population without previous AF.”
To this end, Johnson and colleagues evaluated participant data from the ONTARGET and TRANSCEND trials.
ONTARGET included 25,620 participants and compared the effect of ramipril 10 mg daily compared with telmisartan 80 mg daily or their combination. TRANSCEND included 5,926 participants with ACE inhibitor intolerance and compared telmisartan 80 mg daily with placebo.
Both trials included participants at high risk for CV events, defined as age 55 years or older and either prior CVD, stroke/transient ischemic attack or high-risk diabetes with end-organ damage.
The present analysis included 27,391 participants from both trials (mean age, 66 years; 71% men).
The average sodium intake of the overall cohort was estimated to be 4.8 g per day using the Kawasaki formula.
During an average follow-up of 4.6 years, 5.7% of participants experienced incident AF.
After multivariable adjustment, the researchers observed a J-shaped association between sodium intake and risk for AF.
They reported that a sodium intake of at least 8 g per day was associated with an approximately 32% greater risk for incident AF compared with a daily intake of 4 g to 5.99 g (HR = 1.32; 95% CI, 1.01-1.74).
Among participants with sodium intake of more than 6 g per day — 19% of the cohort — every additional 1 g per day increase was associated with a 10% greater risk for incident AF, but no lower risk was observed at levels below 6 g per day.
These data suggested that reducing daily sodium intake to 6 g per day in patients at high risk for AF may lower risk for incident AF, the researchers wrote.
“Our study found no evidence to support low sodium intakes (< 3 g per day) compared with moderate levels (ie, at the population mean of 3-5 g per day), and there may be a higher risk of AF with low compared with moderate sodium intakes,” the researchers wrote. “Our findings suggest a need for trials testing effects of both high and low vs. moderate sodium intakes with the use of intermediate biomarkers of AF risk and ideally long-term trials of new AF in patients at high risk.”
The researchers noted that a limitation of this study was the likelihood of the Kawasaki formula to overestimate sodium intake from fasting morning urine compared with 24-hour urine collection. Therefore, the threshold of 6 g of sodium per day for increased AF risk may actually be lower.
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