heart failure: aggressive sodium restricton not help

 An international trial found that attempts to reduce dietary sodium to <1500 mg/d in ambulatory heart failure patients did not reduce clinical events, in the Sodium-HF trial (see chf sodium restriction not help Lancet2022 in dropbox or doi.org/10.1016/ S0140-6736(22)00369-5) 

 

 

Details: 

-- 806 patients from 26 sites in six countries who had chronic pretty severe heart failure (NYHA functional class 2-3) and on optimally tolerated guideline-directed medical treatment were randomized in an open-label trial to a low-sodium diet (<100mmol, which is equivalent to 1500mg/d), versus usual care, from 2014-2020 

-- median age 67, 33% women, 58% from Canada/20% Australia and New Zealand/22% from Mexico Chile and Colombia, 50% ever smokers/50% never smokers, BMI 30, heart rate 69, blood pressure 118/70 

-- 68% diagnosed with heart failure for >1 year, 33% hospitalized for heart failure in the past 12 months, ejection fraction 36% (range 28% to 48%), NYHA functional class 2 in 72%/3 in 27% 

-- medications: beta blocker 86%/ACE or ARB 66%/sacubitril-valsartan 15%/mineralocorticoid antagonist 58%, implantable cardioverter-defibrillator 24%, pacemaker 8%, cardiac resynchronization therapy 9% 

-- median B-type natriuretic peptide (BNP) 197 pg/ml (IQR 83-492) and median N-terminal pro-BNP 801 pg/ml (IQR 335-1552) 

-- major comorbidities: hypertension 22%/CAD 46%/atrial fibrillation 40%/diabetes 36% 

-- exclusion criteria: already being on low-sodium 1500mg diet, serum sodium of <130 mmol/L, eGFR <20 

-- dietary materials were developed (meal plans and menus) and tested in a pilot study, then locally adapted to reflect the regional nature of diets 

    -- patients in the low-sodium group were provided a set of six daily sample menus according to their energy requirements, energy distribution, and extent of sodium restriction, versus their normal diet; the diets were normocaloric (ie not for weight loss) with 15-20% protein/50-55% carbohydrates/25-30% fat/7% saturated fat 

    -- usual care group was given general advice to restrict dietary sodium 

-- intervention was for 12 months, with follow-up for an additional 12 months. clinic visits at baseline, at six months, and at 12 months (though there were two extra visits at three months and nine months in the intervention group to support dietary adherence) 

-- dietary sodium intake was assessed using a 3-day food record at baseline, six months and at 12 months in both groups 

-- primary outcome: composite of cardiovascular-related hospital admissions, cardiovascular-related emergency department visits, or all-cause death within 12 months 

-- safety data was also collected 

-- secondary endpoints: time to the first event within the event type; quality of life via the Kansas City Cardiomyopathy Questionnaire (KCCQ) overall summary score, clinical summary score, and physical limitations score; change in the 6-minute walk distance; and change in NYHA functional class from baseline to 12 months 

-- prespecified subgroup analyses were for those >65yo vs <65yo, eGFR <60 vs >60, diabetes, hypertension, left ventricular ejection fraction <40% vs >40% 

 

Results: 

-- no significant difference in the groups at 12 months in terms of body weight, systolic blood pressure, calorie intake, fluid intake, or potassium intake 

-- median sodium intake decreased from 2286 mg/d (IQR 1653-3005) to 1658 mg/d (IQR 1301-2189) in the low-sodium group, versus from 2119 mg/d (IQR 1673-2804) to 2073 mg/d (IQR 1541-2900) in the usual care group 

 

-- primary outcome at 12 months: 

    -- low-sodium group: 60 events (15%) of 397 patients 

    -- usual care group: 70 events (17%) of 409 patients 

        -- HR 0.89 (0.63-1.26), p=0.53, not statistically significant 

-- all-cause death: 

    -- low-sodium group: 22 (6%) of patients 

    -- usual care: 17 (4%) of patients 

        -- HR 1.38 (0.73-2.60), p=0.32, not statistically significant 

-- cardiovascular-related hospitalizations: 

    -- low-sodium group: 40 (10%) of patients 

    -- usual care: 51 (12%) of patients 

        -- HR 0.82 (0.54-1.24), p=0.36, not statistically significant 

-- cardiovascular-related ED visits: 

    -- low-sodium group: 17 (4%) of patients 

    -- usual care: 15 (4%) of patients 

        -- HR 1.21 (0.60-2.41), p=0.60, not statistically significant 

-- no significant difference in the above outcomes when adjusting for age, sex, NYHA functional class, baseline calorie intake, baseline sodium intake, ejection fraction, BMI, eGFR, and presence of implantable cardioverter-defibrillator 

 

-- No safety events reported 

 

-- quality-of-life changes: 

    -- KCCQ physical limitation scores: the mean change from baseline, after adjusting for the baseline score: 

        -- overall summary score: 3.38 points (0.79-5.96) difference, with p=0.011 

        -- clinical summary score was 3.29 points (0.74-5.83) difference, with p=0.017 

            -- though it appears that the minimally clinically important difference in quality of life scores seems to be a threshold of 5 points 

    -- six-minute walk test: no difference 

    -- NYHA functional class at 12 months: low-sodium group had greater likelihood of improving by one NYHA class than the usual care group, OR 0.59 (0.40-0.86), p=0.0061 

 

Commentary: 

-- prior studies on salt restriction in patients with heart failure have had mixed results, perhaps related to the study design, levels of sodium restriction achieved, study duration and demographics of the patients. The above study was designed to use regularly consumed foods and not specially prepared diets (hence, being referred to as a pragmatic trial), in order to make the results generalizable 

 

-- the general conclusion what there was that there was no evident clinical benefit from 12 months of a low-sodium diet, which did achieve significantly less sodium consumption (though not quite reaching the goal of <1500 m/d), as evidenced particularly by the lack of decrease in ED visits and hospitalizations (and we might expect these outcomes would happen even in the relatively short 12-month time period of the study, especially so in patients with pretty severe heart failure as in this study with NYHA functional class 2-3)

 

-- a 2013 report from the Institute of Medicine highlighted the lack of good quality studies on salt and heart failure, but strongly questioned the utility of lowering sodium intake below 2300 mg/d (see http://gmodestmedblogs.blogspot.com/2013/11/dietary-sodium-and-disease.html ). This IOM report comments on a prior CDC report finding that there was essentially no difference in sodium intake in those who were supposed to adhere to a 1500 mg/d vs 2300 mg/d intake. also see another CDC report finding more than three out of four people at high risk for heart disease and stroke consume more than 2300 mg of sodium a https://www.cdc.gov/media/releases/2016/p0106-sodium-intake.html

-- the relationship between salt intake and hypertension is complex, with some patients being more salt sensitive than others. However, there seems to be a general relationship as well as consistent impressive data suggesting that lowering sodium and increasing potassium is helpful (see http://gmodestmedblogs.blogspot.com/2021/09/hypertension-salt-substitute-dec-risk.html ) 

 

Limitations: 

-- this was still only a 12-month study, and though several of the clinical outcomes should have been apparent in that time period, longer follow-up would have been useful to assess its validity with longer-term results 

-- and there was a small sample size (400 in each group), which also limits the assessment of general clinical impact 

-- though KCCQ assessments favored the low-salt group, these results were of unclear clinical significance, and, if any, were only minimal (given that a 5-point difference is considered clinically meaningful, and the differences found were around 3 points) 

-- though these results were from six countries with varied diets, it may be hard to generalize them to other countries with other dietary patterns. For example, the vast majority of the US population has a median sodium intake well above the baseline (3,400 mg/d as of 2/25/2022: , vs the 2200 mg/d in the above study!!! ). see https://www.fda.gov/food/nutrition-education-resources-materials/sodium-your-diet#:~:text=Americans%20eat%20on%20average%20about,recommended%20limits%20are%20even%20lower  

-- the study involved assessment of sodium intake was by food records, which are less accurate than performing several 24-hour urinary sodium excretion assessments. And this is a potential concern given the pretty dramatic change in the 1500 mg/d group, which is typically pretty difficult to achieve in a large groups of people

-- as an open label study, patients were not masked to study group assignment, which could bias their results. 

-- this study was limited to a specific goal: lowering consumed sodium. The reality of clinical care is that diet might serve several goals, including weight loss. would the same results apply to a more patient-centered and holistic diet?

 

So, this study did find that people were able to decrease their sodium intake significantly and maintain that for the 12-month study. But a few issues: 

-- they achieved the 12-month lowered sodium intake by patient interactions every 3 months; i think this is an important point: lifestyle changes are very hard to do in our society (too much reinforcement for high sodium as well as calorie-dense diets, for example, through advertising or placing high salt/junk foods in appealing places in the grocery stores, or signature group events (football games....)

    -- though it is very difficult to change dietary habits, the US does have very high salt intake, largely from processed foods, snacks, and fast foods. It is notable that when people eat lower salt foods regularly, their taste for salt is enhanced 

-- lowering sodium intake from 2300 to 1700 mg/d as in this study did not have evident clinical benefit in patients with pretty severe heart failure, suggesting strongly that the highly restricted 1500mg/d sodium intake should not be a target of care

    -- several studies have found that lowering sodium to 2300 mg/d may still be clinically useful (see the IOM report above, though several of these studies are not of great quality), but little information about a lower sodium intake target and some suggestion that that is harmful 

-- the US sodium consumption is very, very high, and is clearly related to hypertension, a key factor in the development of heart failure, and an important target of care

-- so, this all points to moderation in our clinical recommendations: decreasing high salt foods seems appropriate (and, I suspect many of us have in fact found that patients with moderate-to-severe heart failure do have clinical deterioration with high salt meals), but recommending a more severe salt restriction may be onerous (and also does not seem to work very often), and may be counterproductive (many people may not pay attention to pretty draconian dietary changes, since they seem unattainable). My sense is that engaging the patient around their diets, their likes/dislikes, and then focusing on some specific food types consumed, that the patient may be able to decrease sodium consumption (via motivational interviewing). close followup (perhaps through nutritionists/nurses/etc) may be an important part of heart failure care, and potentially lead to a decrease in meds (esp diuretics) in heart failure management and improved clinical outcomes.

geoff

 

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