Too Little Salt May Have an Adverse Impact on People Living With HFpEF

The prognosis of patients living with heart failure with preserved ejection fraction (HFpEF) was shown to be worse in a new study from investigators at the Department of Cardiology Sun Yat-sen University First Affiliated Hospital, in China, if their doctor prescribed a very strict cooking salt regimen.

This study was published online today in Heart, and it is a subanalysis of the multicenter, international Aldosterone Antagonist Therapy for Adults With Heart Failure and Preserved Systolic Function (TOPCAT) trial. The primary end point was a composite of cardiovascular (CV) death, HF hospitalization, and aborted cardiac arrest; the secondary end points were CV death, all-cause death, and HF hospitalization. Study participants were divided into 2 cohorts: cooking salt score of 0 (n = 816) and cooking salt score greater than 0 (n = 897). Median (IQR) ages were equivalent in the groups, at 72 (63-79) and 73 (64-79) years. Most participants in both groups were White (80.8% and 76.9%), had a previous HF hospitalization (62.6% and 55.1%), had hypertension (90.0% and 90.2%), and were taking diuretics (92.2% and 86.8%). All cooking salt scores were self-reported.

“There is a lack of high-quality evidence to support salt intake restriction in patients with HF,” the authors wrote. “As salt intake could significantly affect volume status and neurohormonal status, which might play a role in the response to treatment in HFpEF, we aimed to explore the effect of cooking salt restriction in patients with HFpEF with data from the TOPCAT trial.”

Overall, those in the group with a cooking salt score greater than 0 had a 24% reduced risk of CV death, HF hospitalization, and aborted cardiac arrest (HR, 0.76; 95% CI, 0.638-0.906; P = .002), as well as a 26% reduced risk of HF hospitalization specifically (HR, 0.737; 95% CI, 0.603-0.900; P = .003). The changes seen in all-cause and CV death were determined not to be statistically significant, at reductions of 16% (HR, 0.838; 95% CI, 0.684-1.027; P = .088) and 22% (HR, 0.782; 95% CI, 0.598-1.020; P = .071), respectively.

Participants in the group with a cooking salt score above 0 were heavier (97.34 [25.81] vs 91.08 [23.76] kg) and had lower diastolic blood pressure (BP) (70.20 [11.28] vs 72.35 [11.61] mm Hg). Additional investigation via Spearman correlation analyses produced significant positive correlations between systolic and diastolic BPs, serum sodium, and chloronium levels, “suggesting that cooking salt score could at least partially reflect salt intake of these patients.”

The medium follow-up for the study was 2.93 years.

Additional cubic spline analyses showed that a cooking salt score above 6 correlated with a plateauing of the risk of the primary end point and all-cause death, that risk of CV death trended upward, and that risk of HF hospitalization still decreased. Further, younger patients were shown to derive a greater benefit from cooking salt compared with older patients (70 years or younger vs 70 years and older), as were patients of a non-White race—both regarding the primary study end point.

A principal complication among patients with HF that arises from overly strict salt-intake guidelines is volume contraction, which can lead to HF compensation, the authors highlighted. In addition, previous studies show that excessively low salt intake can aggravate HF, lower cardiac output, and increase peripheral resistance. An additional potential adverse effect is renal damage, which the authors say is a known predictor of worse HF prognosis.

“Overstrict dietary salt intake restriction could harm patients with HFpEF and is associated with worse prognosis,” the study investigators concluded. “Physicians should reconsider giving this advice to patients with HFpEF.”

They also suggest high-quality trials to determine the optimal salt intake range for patients with HFpEF.

Reference

Li J, Zhen Z, Huang P, Dong YG, Lie C, Liang W. Salt restrictions and risk of adverse outcomes in heart failure with preserved ejection fraction. Heart. Published online July 18, 2022. doi:10.1136/heartjnl-2022-321167