Ultrashort Heart Rate Variability for Early Risk Stratification in Pneumonia Patients: Preliminary Analysis.

BACKGROUND:Pneumonia patients are susceptible to autonomic nervous system changes. Ultrashort HRV (usHRV) is the measurement of cyclic changes in heart rate over a period < 5 minutes. OBJECTIVES:To describe usHRV in patients with pneumonia and assess the correlation with mortality. METHODS:We conducted a retrospective analysis, which included patients diagnosed with pneumonia in the emergency department (ED). UsHRV indices were calculated from a 10-second ED electrocardiogram and correlated with mortality utilizing logistic and Cox regressions. RESULTS:The study comprised 240 patients. Mortality rates over 30, 90, and 365 days were 13%, 18%, and 30%, respectively. usHRV frequency-domain parameters had significant univariate correlations with mortality. Normalized low frequency (LF) and high frequency (HF) were correlated with 30-, 90-, and 365-day mortality in an opposite direction (odds ratio [OR] 0.094, P = 0.028 vs. OR 4.589, P =0.064; OR 0.052, P = 0.002 vs. OR 6.975, P =0.008; OR 0.055, P < 0.001 vs. OR 7.931, P < 0.001; respectively). Survival analysis was conducted for a follow-up median period of 5.86 years (interquartile range 0.65-9.77 years). Univariate Cox proportional hazard regression revealed time-domain indices with significant correlation with survival (SDNN and RMSSD; hazard ratio [HR] 1.005, 1.005; P = 0.032, P = 0.005; respectively) as well as frequency-domain parameters (normalized LF, HF, LF/HF ratio, and total power; HR 0.102, 5.002, 0.683, 0.997, respectively; P < 0.001). CONCLUSIONS:usHRV may predict mortality in pneumonia patients and serve as a novel risk stratification tool.