Intradialytic exercise preconditioning: an exploratory study on the effect on myocardial stunning

Background Exercise preconditioning provides immediate protection against cardiac ischemia in clinical/preclinical studies in subjects without chronic kidney disease. In individuals requiring renal replacement therapy, hemodialysis (HD) results in significant circulatory stress, causing acute ischemia with resultant recurrent and cumulative cardiac injury (myocardial stunning). Intradialytic exercise (IDE) has been utilized to improve functional status in individuals receiving HD. The objective of this study was to explore the role of IDE as a preconditioning intervention and assess its effect on HD-induced myocardial stunning. Methods We performed a single-center cross-sectional exploratory study in adults on chronic HD participating in a clinical IDE program. HD-induced cardiac stunning was evaluated over two HD sessions within the same week: a control visit (no exercise) and an exposure visit (usual intradialytic cycling). Echocardiography was performed at the same three time points for each visit. Longitudinal strain values for 12 left ventricular segments were generated using speckle-tracking software to assess the presence of HD-induced regional wall motion abnormalities (RWMAs), defined as a >= 20% reduction in strain; two or more RWMAs represent myocardial stunning. Results A total of 19 patients were analyzed (mean age 57.2 +/- 11.8 years, median dialysis vintage 3.8 years). The mean number of RWMAs during the control visit was 4.5 +/- 2.6, falling to 3.6 +/- 2.7 when incorporating IDE (a reduction of -0.95 +/- 2.9; P=0.17). At peak HD stress, the mean number of RWMAs was 5.8 +/- 2.7 in the control visit versus 4.0 +/- 1.8 during the exposure visit (a reduction of -1.8 +/- 2.8; P=0.01). Conclusion We demonstrated for the first time that IDE is associated with a significant reduction in HD-induced acute cardiac injury.