Restricting salt intake is considered a key component of heart failure treatment, but restricting it too much may actually worsen the outcomes for people with a common form of the condition, suggests research published online in the journal Heart.
Younger people and those of black and other ethnicities seem to be most at risk, the findings indicate.
Salt restriction is frequently recommended in heart failure guidelines, but the optimal restriction range (from less than 1.5 g to less than 3 g daily) and its effect on patients with heart failure with preserved ejection fraction isn’t clear as they have often been excluded from relevant studies.
Heart failure with preserved ejection fraction, which accounts for half of all heart failure cases, occurs when the lower left chamber of the heart (left ventricle) isn’t able to fill properly with blood (diastolic phase), so reducing the amount of blood pumped out into the body. In a bid to explore the association with salt intake further, the researchers drew on secondary analysis of data from 1713 people aged 50 and above with heart failure with preserved ejection fraction who were part of the TOPCAT trial. A phase III, randomised, double-blind, placebo-controlled study, this trial was designed to find out if the drug spironolactone could effectively treat symptomatic heart failure with preserved ejection fraction.
Participants were asked how much salt they routinely added to the cooking of staples, such as rice, pasta, and potatoes; soup; meat; and vegetables, and this was scored as: 0 points (none); 1 (⅛ tsp); 2 (¼ tsp); and 3 (½+tsp).
Their health was then monitored for an average of 3 years for the primary endpoint, a composite of death from cardiovascular disease or admission to hospital for heart failure plus aborted cardiac arrest. Secondary outcomes of interest were death from any cause and death from cardiovascular disease plus hospital admission for heart failure. Around half the participants (816) had a cooking salt score of zero: more than half of them were men (56%) and most were of white ethnicity (81%). They weighed significantly more and had a lower diastolic blood pressure (70 mm Hg) than those with a cooking salt score above zero (897).
