Beyond decongestion: sustained low-efficiency dialysis and frailty improvement in patients with advanced cardiorenal syndrome

Background

Patients with advanced cardiorenal syndrome who are not candidates for mechanical circulatory support or heart transplantation represent a high-risk, understudied population, and evidence supporting guideline-directed medical therapy in this setting is limited. Persistent congestion and volume overload are common and often refractory to diuretics. Sustained low-efficiency dialysis (SLED) may provide a haemodynamically tolerable strategy for gradual fluid removal in this context.

Purpose

To evaluate the effects of SLED as a potential alternative to purely palliative care in persistently congested patients with advanced heart failure and renal dysfunction who are unsuitable for advanced therapies, with a focus on frailty.

Methods

We conducted a single-centre, non-randomised retrospective cohort study including patients hospitalised with advanced heart failure, persistent congestion, and renal dysfunction between September 2002 and December 2024. The index date was defined as the date on which SLED was deemed clinically indicated. Patients who initiated SLED comprised the SLED group, while those who declined SLED and continued with standard medical therapy comprised the standard therapy group. Frailty was assessed using the Rockwood Clinical Frailty Scale at the index date and at last follow-up. Continuous variables were analysed with t-tests and categorical variables with chi-square tests.

Results

We analysed 139 patients (SLED, n=107; standard therapy, n=32). Groups were broadly comparable in age (75 vs 79 years, p=0.116), sex (men: 48% vs 34%, p=0.185), left ventricular ejection fraction (median 50% in both; HFpEF in 58% vs 53%, p=0.737), and heart failure aetiology (hypertensive heart disease: 47% vs 34%, p=0.055). NT-proBNP levels were markedly elevated in both groups (17,052 vs 18,670 pmol/L, p=0.514). Clinical signs of congestion were similar, although acute respiratory failure was more frequent in the SLED group.

Baseline frailty was higher in the standard therapy group and remained unchanged during follow-up (median Rockwood 7 at baseline and follow-up; median follow-up 3 months, IQR 1–7). In contrast, frailty improved in the SLED group, with median Rockwood scores decreasing from 6 at baseline to 5 at last follow-up after a median of 10 months (IQR 6–34; p<0.001).

Conclusions

In persistently congested patients with advanced heart failure and renal dysfunction who were not eligible for advanced therapies, SLED was associated with a clinically meaningful improvement in frailty over time, whereas frailty remained stable in those managed with standard therapy alone. These findings suggest that SLED may provide benefits beyond decongestion, potentially improving functional status in a population often limited to supportive care. Prospective studies are warranted to confirm these observations and to better define patient selection, timing, and outcomes.