High Ultrafiltration Rates Increase Troponin Levels in Stable Hemodialysis Patients

Abstract

Background: An elevated troponin level is commonly found in asymptomatic patients on hemodialysis (HD) and is associated with higher risk of mortality and major adverse cardiovascular events. The underlying mechanism for the association between adverse outcomes and elevated troponin levels has not been elucidated. Methods: Two hundred thirty-six stable chronic HD patients from 2 tertiary care centers were enrolled in this study. We measured pre-dialysis troponin I levels with routine monthly bloods for 3 consecutive months. Troponin I was considered to be elevated if it exceeded the laboratory reference range of 0.06 μg/l. Results: The study population had a mean age of 67.5, 56% were male, 47% had diabetes and 28% had pre-existing coronary artery disease. Eighty-eight positive troponin values were recorded (13% of the available values) in 52 patients. In a repeated measures linear random effects model (univariate analysis), high ultrafiltration (UF), high inter-dialytic weight gain, and duration of the dialysis session, but not intra-dialytic hypotension, were associated with troponin I elevation. In the multivariate model, only high UF explained troponin I elevation (p = 0.04). The intraclass correlation coefficient was found to be 5.8%, suggesting that observed variability is within and not between subjects, with session-related parameters being more important than inter-individual differences. Conclusions: A high UF rate during HD is associated with a biochemical evidence of myocardial injury. If confirmed, efforts to avoid rapid UF, protect residual kidney function or minimize weight gain between sessions may impact cardiovascular outcomes in this high-risk population.