Although salt restriction is seen as a crucial part of treating heart failure, research published online in the journal Heart reveals that excessive salt restriction may worsen the results for those who have a common form of the ailment.
The data suggest that those who are younger and of black or other ethnic backgrounds appear to be most at risk.
The ideal salt restriction range (from less than 1.5 g to less than 3 g daily) and its impact on patients with heart failure with preserved ejection fraction aren’t entirely clear because these patients are frequently left out of relevant studies. Salt restriction is frequently advised in heart failure guidelines.
Half of all cases of heart failure are classified as heart failure with preserved ejection fraction, which happens when the left ventricle, the heart’s lower left chamber, is unable to fill completely with blood during the diastolic phase.
Researchers used secondary analysis of data from 1713 individuals aged 50 and up who participated in the TOPCAT study and had heart failure with preserved ejection fraction to further investigate the association with salt intake.
This phase III trial examined the efficacy of spironolactone in the treatment of symptomatic heart failure with preserved ejection fraction. It was a randomized, double-blind, placebo-controlled study.
On a scale of 0 (none), 1 (1/8 tsp), 2 (1/4 tsp), and 3 (1+tsp), participants were asked how much salt they regularly added to cook rice, pasta, and potatoes; soup; meat; and vegetables.
The primary objective, a composite of death from cardiovascular disease or hospital admission for heart failure plus abortive cardiac arrest, was then examined for an average of 3 years to determine the participants’ overall health. Secondary outcomes of interest included hospital admission for heart failure along with death from any cause and death from cardiovascular disease.
Moreover, half of the participants (816) had a cooking salt score of zero; 56 percent of them were men, and the majority were white in ethnicity (81 percent). They weighed considerably more and had diastolic blood pressure that was significantly lower (70 mm Hg) than those who had a cooking salt score above zero (897).
Additionally, they had a lower left ventricular ejection fraction, were more likely to have type 2 diabetes, had worse kidney function, and had more frequent hospital admissions for heart failure (lower cardiac output).
Participants with a cooking salt score greater than zero had a considerably reduced risk of the primary endpoint than those with a cooking salt score of zero, mostly because they were less likely to be hospitalized for heart failure. But they weren’t any less likely to die from any cause or from heart disease than people whose cooking salt score was 0.
Regarding the primary outcome and admission to the hospital for heart failure, people under the age of 70 were considerably more likely to benefit from adding salt to their cooking than those over the age of 70.
Similar to this, while the numbers were small, people of black and other ethnicities appeared to benefit more from adding salt to their cuisine than people of white ethnicity.
Gender, prior heart failure hospitalization, and administration of heart failure drugs were not linked to increased risks of the assessed outcomes or cooking salt score.
Because this is an observational study, it cannot determine the cause. The researchers recognize that not all relevant information from the TOPCAT study was accessible and the cooking salt score was self-reported. And reverse causation can’t be ruled out, which means that people with worse health might have been told to cut back on salt even more.
In both the general population and people with high blood pressure, lower sodium consumption is typically linked to lower blood pressure and a decreased risk of cardiovascular disease. It is believed to reduce fluid retention and the activation of the hormones responsible for controlling blood pressure.
But researchers say that limiting salt intake to control heart failure is not as simple as it sounds. It might cause the intravascular volume to constrict, which would lessen congestion and the need for water pills to reduce fluid retention.
However, the researchers note that the results of their study indicate that the volume of plasma in the blood—a sign of congestion—was not significantly associated with cooking salt score, indicating that low sodium intake did not reduce fluid retention in people with heart failure who had preserved ejection fraction.
“Overstrict dietary salt intake restriction,” as concluded by the authors, “could harm patients with [heart failure with preserved ejection fraction] and is associated with worse prognosis. Physicians should reconsider giving this advice to patients.”
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