Heart Rate Variability and Baroreflex Sensitivity as Predictors of Mortality in Patients with Aneurysmal Subanachroid Haemorrhage

The relationship between baroreceptors sensitivity(BRS), heart rate variability (HRV) and the mortality in patients after aneurysmal subarachnoid hemorrhage (aSAH) is poorly understood. The aim of this study was to investigate whether HRV and BRS monitoring could predict mortality. Data from 58 aSAH patients admitted to the University Hospital in Wroclaw was analyzed. BRS was calculated using a sequential cross-correlation method. HRV was described in time domain with a standard derivation of the difference between sequential beats (SDNN) and in the frequency domain with a spectral power of RR time series in the low frequency range (HRV_LF: 0.04–0.15 Hz). Differences between parameters in survivors vs. non-survivors were tested with the U Mann-Whitney statistic. Threshold values were determined with ROC curves. Threshold value of BRS was 3.20 ms/mmHg (AUC 0.76; Z=2.96, p=0.003) and patients with low BRS were more likely to die (FCox = 9.84, p=0.00004). The thresholds of HRV_LF and SDNN were as follows: 202.0 ms² (AUC 0.69; Z=2.07, p=0.039) and 15.09 ms (AUC 0.75; Z=3.06, p=0.002), respectively. Below these thresholds the mortality was significantly higher (FCox = 5.86, p=0.004 and FCox = 5.25, p=0.001, respectively). BRS, HRV_LF and SDNN were reduced in non-survivors (14 patients) when compared to survivors (44): p=0.004, p=0.037 and p=0.005, respectively. BRS and HRV parameters are important predictors of mortality in aSAH. These findings indicate that parameters, identified during long-term clinical monitoring, could provide useful information for treatment of neurological patients. This study was funded by the National Science Centre (Poland) under Grant No. 2013/09/B/NZ4/01343.