No CV benefits with cooler dialysate

The use of a cooler dialysate during maintenance haemodialysis does not offer cardiovascular (CV) benefits to patients in the MyTEMP trial.

There was no difference in the primary composite outcome of CV death or hospital admission between the cooler and standard dialysate temperature groups, reported study investigator Dr Amit Garg from the Victoria Hospital in London, Ontario, Canada at Kidney Week 2022.

“For nephrologists who currently use cooler dialysate for individualized patient care, the MyTEMP results provide an opportunity to reflect on practice,” he said.

Trial misses primary endpoint

A total of 15,413 patients were included in MyTEMP, representing roughly 4.3 million haemodialysis treatments. Before starting dialysis, the dialysate temperature was set 0.5–0.9°C lower than the patients’ body temperature to as low as 35.5°C in the cooler dialysate group and 36.5°C in the standard dialysate group.

The primary outcome of CV death or hospital admission for myocardial infarction (MI), ischaemic stroke, or congestive heart failure (CHF) occurred in 1,711 patients (21.4 percent of 8,000) in the cooler dialysate group vs 1,658 patients (22.4 percent of 7,413) in the standard dialysate group (adjusted hazard ratio [adjHR], 1.00; p=0.93).

There were no differences in the individual components of the primary composite outcome during the 4-year trial. The cooler dialysate had also no effect on  the key secondary endpoint of systolic blood pressure (BP). Average drop in intradialytic systolic BP was 26.6 mm Hg with cooler dialysate vs 27.1 mm Hg with the standard  dialysate (mean difference, -0.5 mm Hg; p=0.14).

Moreover, there was no difference in the risk of intradialytic hypotension (IDH) between groups. A quarter of patients in the cooler dialysate group described the experience as “the worst possible feeling.”

Garg said the lack of CV benefit, plus the likelihood of patient discomfort, provides no justification for the use of cooler dialysate as a centre-wide policy.

The end of a cool idea?

In an accompanying commentary, Drs Nicholas Selby and Maarten Taal from the University of Nottingham in Nottingham, UK cautioned against tossing out the practice of using cooler dialysate this early. [Lancet 2022;doi:10.1016/S0140-6736(22)01988-2]

“While the MyTEMP findings were impressive, these should not be interpreted as definitive evidence that cooling the dialysate is ineffective for individual patients.”

They cited a meta-analysis of 26 trials showing a 70-percent reduction in IDH rate and a 12-mm Hg increase in intradialytic mean arterial pressure with the use of cooler dialysate in patients receiving chronic haemodialysis. [Clin J Am Soc Nephrol 2016;11:442-57]

IDH is a well-recognized problem among patients on haemodialysis and is associated with significant vascular and cardiac adverse outcomes. Cool dialysate may be an effective approach to reducing IDH by promoting peripheral vasoconstriction. [Ther Apher Dial 2019;23:145-152]