Decoding the Risk: Heart Rate Variability as a Powerful Predictor of Sudden Cardiac Death in Chronic Hemodialysis Patients—A 36-Month Prospective Study

Introduction: This study aimed to estimate the impact of the C-reactive protein (CRP), serum albumin, lipids, and heart rate variability (HRV) on sudden cardiac death (SCD) in chronic hemodialysis patients (CHPs) to derive the strongest predictor for SCD. Methods: In this prospective study, 90 CHPs, average age 59.2 ± 11.4 years, were observed over a three-year follow-up period to detect SCD. HRV, with a focus on standard deviation of normal-to-normal intervals (SDNN), was measured using a 12- channel ECG. Peripheral blood samples were obtained from all participants, followed by routine blood tests: urea, creatinine, lipid status, hemoglobin, hs-CRP, albumin, and calcium - phosphorus product. Key Findings: The mean SDNN was 107.97 ± 24.51 ms. Among CHPs, SDNN was significantly lower in deceased patients (79.20 ± 14.84 ms) compared to survivors (106.91 ± 23.09 ms, P = 0.0097). The mean survival time for SCD was 34.8 ± 5.3 months. Cox regression coefficients b (-0.1146, 0.1224, 0.0781, and 0.0934), hazard ratio (HR) (0.8917, 1.1303, 1.0812, and 1.0979), and p-value (0.042, 0.203, 0.680 and 0.378) for SDNN, hs-CRP, albumin and hemodialysis (HD) duration, respectively, showed strongest predictive impact for SCD of HRV (SDNN) covariate, with hazard rate rising by 1.12145 (12.45%) for every single unit decrease of SDNN. Receiver operating characteristics (ROC) analyses for SDNN were as follows: area under the curve (AUC) = 0.835 (P < 0.001), with a cut-off value of ≤84 ms (sensitivity 80.0%, specificity = 83.53%). AUC results for covariate albumin (AUC = 0.542, P = 0.766), CRP (AUC = 682, P = 0.204), and HD duration (AUC = 0.558, P = 0.717) did not reach significance in predicting the risk for SCD. Conclusion: HRV proved to be a robust and independent predictor of sudden SCD in CHPs, with HR increasing by 11.48% for each unit decrease in SDNN (ms). In contrast, hs-CRP, serum albumin, lipids, and HD did not demonstrate a statistically significant effect on SCD risk prediction in CHPs.