E-Mail karger@karger.com Original Paper Nephron Clin Pract DOI: 10.1159/000360542 Parathyroid Hormone and Heart Rate Variability in Haemodialysis Patients Dimitrios Poulikakos a, b Marek Malik c Debasish Banerjee a, b a Cardiovascular Sciences Research Centre, St. George’s University of London, b Renal and Transplantation Unit, St. George’s Hospital NHS Trust, and c Imperial College of Science Technology and Medicine, London, UK phate correlated negatively with LF F (r = –0.427, p = 0.003), HF F (r = –0.442, p = 0.002) and HF L (r = –0.307, p = 0.040). Conclusion: High PTH and phosphate are associated with depressed HRV in non-diabetic dialysis patients. Prospective studies are needed to evaluate the role of mineral abnor- malities in autonomic imbalance and arrhythmic risk in HD patients. © 2014 S. Karger AG, Basel Introduction Sudden cardiac death accounts for two thirds of total cardiovascular mortality in the haemodialysis (HD) pop- ulation [1]. Traditional cardiovascular risk factors are common in patients with end-stage renal disease [2] but disproportionally elevated arrhythmic risk has been at- tributed to additional risk factors related to complica- tions arising from the uraemic status [2]. Secondary hyperparathyroidism is a universal compli- cation in HD patients [3]. Elevated parathyroid hormone (PTH) levels have been associated with increased mortal- ity [4, 5] and especially sudden cardiac death [6] in these patients. High PTH has also been associated with sudden cardiac death in non-CKD patients with [7] and without [8] clinically evident cardiovascular disease. Key Words Heart rate variability · Haemodialysis · Parathyroid hormone Abstract Background: Depressed heart rate variability (HRV) reflects abnormal cardiac autonomic regulation and has been linked with increased cardiovascular risk and sudden cardiac death. High parathyroid hormone (PTH) levels have also been as- sociated with an increased risk of sudden cardiac death in haemodialysis (HD) patients. Our aim was to investigate the association between HRV indices and PTH in HD patients. Methods: Continuous intradialytic electrocardiograms were repeated in stable HD patients 5 times every 2 weeks. The absolute values of high-frequency (HF) and low-frequency (LF) HRV components were calculated every 5 min and aver- aged during the first and last hour of each recording (distin- guished by subscripts F and L, respectively). Pre-HD PTH, cor- rected calcium, and phosphate levels were measured before the first recording. Results: Data were analysed for 75 sub- jects aged 60 ± 15, 32% females, 37% diabetics. Baseline bio- chemical parameters were PTH 44 ± 32 pmol/l, calcium 2.3 ± 0.2 mmol/l, and phosphate 1.6 ± 0.4 mmol/l. All HRV indices showed intra-subject stability over the 5 recordings. Diabet- ics had lower LF L compared to non-diabetics (–5.5 ± 0.5 vs. –5.2 ± 0.5 after logarithmic transformation, p = 0.012). In non-diabetics, PTH correlated negatively with LF L and HF L (LF L r = –0.340, p = 0.020, HF L r = –0.325, p = 0.026) and phos- Received: October 16, 2013 Accepted: February 5, 2014 Published online: ■■■ Dimitrios Poulikakos Cardiovascular Sciences Research Centre St. George’s University of London, Medical School Cranmer Terrace, London SW17 0RE (UK) E-Mail dimitrios.poulikakos  @  stgeorges.nhs.uk © 2014 S. Karger AG, Basel 1660–2110/14/0000–0000$39.50/0 www.karger.com/nec M. Malik and D. Banerjee contributed equally to this work. NEC360542.indd 1 NEC360542.indd 1 24.03.2014 12:18:59 24.03.2014 12:18:59