Randomized Controlled Trial of Individualized Dialysate Cooling for Cardiac Protection in Hemodialysis Patients

Background and objectives Cardiovascular disease is the most common cause of death in patients on hemodialysis (HD). HD-associated cardiomyopathy is appreciated to be driven by exposure to recurrent and cumulative ischemic insults resulting from hemodynamic instability of conventionally performed intermittent HD treatment itself. Cooled dialysate reduces HD-induced recurrent ischemic injury, but whether this confers long-term protection of the heart in terms of cardiac structure and function is not known.Design, setting, participants, & measurements Between September 2009 and January 2013, 73 incident HD patients were randomly assigned to a dialysate temperature of 37°C (control) or individualized cooling at 0.5°C below body temperature (intervention) for 12 months. Cardiac structure, function, and aortic distensibility were assessed by cardiac magnetic resonance imaging. Mean between-group difference in delivered dialysate temperature was 1.2°C±0.3°C. Treatment effects were determined by the interaction of treatment group with time in linear mixed models.Results There was no between-group difference in the primary outcome of left ventricular ejection fraction (1.5%; 95% confidence interval, –4.3% to 7.3%). However, left ventricular function assessed by peak systolic strain was preserved by the intervention (–3.3%; 95% confidence interval, –6.5% to –0.2%) as was diastolic function (measured as peak diastolic strain rate, 0.18 s−1; 95% confidence interval, 0.02 to 0.34 s−1). Reduction of left ventricular dilation was demonstrated by significant reduction in left ventricular end-diastolic volume (–23.8 ml; 95% confidence interval, –44.7 to –2.9 ml). The intervention was associated with reduced left ventricular mass (–15.6 g; 95% confidence interval, –29.4 to –1.9 g). Aortic distensibility was preserved in the intervention group (1.8 mmHg−1×10−3; 95% confidence interval, 0.1 to 3.6 mmHg−1×10−3). There were no intervention-related withdrawals or adverse events.Conclusions In patients new to HD, individualized cooled dialysate did not alter the primary outcome but was well tolerated and slowed the progression of HD-associated cardiomyopathy. Because cooler dialysate is universally applicable at no cost, the intervention warrants wider adoption or confirmation of these findings in a larger trial.