Peri-Diagnostic Heart Rate Variability, Systemic Inflammation, and Survival in Adults with Brain Tumors: An Exploratory Retrospective Cohort Study

Heart rate variability (HRV) has been proposed as an autonomic marker of cancer prognosis, but its independent prognostic value in brain tumors and relationship with systemic inflammation remain uncertain. We retrospectively analyzed 242 adults with histopathologically graded brain tumors. Standard deviation of normal-to-normal intervals (SDNN), root mean square of successive normal-to-normal differences (RMSSD), and relative RR-HRV (rrHRV) were derived from routine 10 s 12-lead electrocardiograms (ECGs) obtained within ±14 days of diagnosis, and C-reactive protein (CRP) within ±28 days. During follow-up, 192 patients (79.3%) died, and median overall survival was 20.5 months. In univariate Cox models, a doubling of rrHRV was nominally associated with lower mortality hazard (HR = 0.886, 95% confidence interval (CI) 0.788–0.996, p = 0.043), whereas SDNN and RMSSD were not. After adjustment for age, sex, World Health Organization (WHO) grade, log2(CRP + 1), and metabolic/systemic comorbidity, no HRV measure was independently associated with mortality (all p ≥ 0.850), and HRV did not improve model fit. Small inverse HRV–CRP associations (Spearman ρ = −0.180 to −0.217) survived false-discovery-rate correction. In this cohort, we found no evidence that routine 10 s ECG-derived HRV was independently associated with mortality or improved the fit of the specified clinical models; prospective studies with standardized pre-treatment recordings are warranted.