A large cohort study found a J-shaped relationship between sodium intake and atrial fibrillation risk in patients with vascular disease or diabetes.
In the study, published in JAMA Network Open, investigators examined the association between estimated sodium consumption and atrial fibrillation (AF) incidence in 27,391 patients with a mean age of 66.3 years who participated in the ONTARGET and TRANSCEND trials; 70.5% of the patients involved in the study were male.
The investigators used the Kawasaki formula to estimate sodium intake from morning urine samples. Although they noted this method was a potential limitation compared with 24-hour urine collections, it has been validated in previous studies.
A high sodium intake (≥ 8 g/day) was associated with a 32% increased risk of AF compared with a moderate intake (4 to 5.99 g/day). Further, a threshold effect was observed—with sodium intake above 6 g/day linked to a 10% increased AF risk for each additional gram consumed. The investigators observed no evidence of reduced AF risk with sodium intake below 3 g/day compared with moderate intake levels. The association between sodium intake and AF risk was more pronounced among patients who had been diagnosed with hypertension.
Among additional findings were:
- The mean estimated sodium intake was 4.8 g/day overall, with 4.9 g/day for men and 4.4 g/day for women.
- During a mean follow-up of 4.6 years, 5.7% (n = 1,562) of the patients developed incident AF.
- Sodium intake was positively associated with systolic blood pressure, with an increase of 0.70 mmHg/g of sodium intake.
- Patients with an estimated sodium intake of 6 g/day or greater comprised 19.1% of the study population.
- The association between sodium intake and AF persisted after adjusting for factors such as age, sex, body mass index, physical activity, smoking status, education, and alcohol use.
The investigators examined potassium intake but found no statistically significant association with AF risk.
Sodium reduction efforts for AF prevention could focus on individuals consuming high-sodium diets (> 6 g/day); however, no benefit in reducing sodium intake below 3 g/day was found. This finding differs from current dietary guidelines recommending a very low sodium intake.
Randomized trials could help researchers better understand the effects of sodium reduction on AF risk, particularly in high-risk patient populations. Investigators suggested such studies may inform future guidelines.
Full disclosures of interest can be found in the original study.