Study on the relationship of National Institutes of Health Stroke Scale score with heart rate variability and cardiac complication in elderly patients with acute cerebral infarction

Objective To investigate the relationship of National Institute of Health Stroke Scale(NIHSS)with heart rate variability(HRV)and cardiac complication in elderly patients with acute cerebral infarction, and to clarify the effect of early drug intervention on the regulation of autonomic nerve function in patients with high NIHSS score. Methods One hundred twenty-six inpatients with first-onset acute cerebral infarction(ACI)(the cerebral infarction group)and 40 healthy subjects with no history of stroke(the control group)were retrospectively enrolled.All subjects underwent examinations of NIHSS and 24 h dynamic electrocardiogram.According to NIHSS score, patients in the cerebral infarction group were divided into 3 subgroups: NIHSS score 0-4 group(n=32), NIHSS score 5-15 group(n=66)and NIHSS score ≥ 15 group(n=28). The difference in HRV parameters were compared between ACI patients and the controls.Ninety-four ACI patients with NIHSS score ≥5 were randomly divided into 2 groups: (1)the traditional treatment group(n=44), taking routine drugs for cerebral infarction; (2)the special treatment group(n=42), taking metoprolol sustained release tablet and Shensonyangxin capsule as add-on to the routine drugs for cerebral infarction.The 24 h dynamic electrocardiogram examination were conducted 30 days after treatment.The differences in HRV parameters and cardiac complications were compared between the two treatment groups. Results In patients with acute cerebral infarction, the time-domain parameters of normal-to-normal intervals(NNI), standard deviation of normal-to-normal intervals(SDNN), square root of the mean squared successive differences between normal-to-normaI RR intervals(RMSSD), percentage of adjacent normal-to-normal intervals that differed more than 50 ms(PNN50), frequency domain parameters low-frequency(LF)power and high-frequency(HF)power were significantly reduced as compared with those in the control group(P<0.05). While, pulse rate and frequency domain parameters of sympathetic vagus balance index(LF/HF)were significantly increased(P<0.05). The time-domain parameters(NNI, SDNN, RMSSD and PNN50)and frequency domain parameters(LF, HF)were significantly reduced in the NIHSS score 5-15 group and NIHSS score ≥15 group as compared with the control group and the NIHSS score 0-4 group(P<0.05). The time-domain parameters(RMSSD and PNN50)and frequency domain parameters(LF and HF)were reduced(P<0.05), and the frequency domain parameters(LF/HF)were increased(P<0.05)in NIHSS score ≥15 group compared with in NIHSS score 5-15 group(P<0.05). Compared with pre-treatment, the special treatment group after treatment showed that the time domain parameters(NNI, SDNN, RMSSD and PNN50)and frequency domain parameters(LF and HF)were significantly increased(P<0.05), the frequency domain parameters(LF/HF)were significantly reduced(P<0.05)and the incidence of cardiac complication(total incidence of atrial arrhythmias and ventricular arrhythmias and cardiac complication)were significantly reduced(P<0.05). As compared with the traditional treatment group after treatment, the special treatment group after treatment showed that the time domain parameters(NNI, SDNN, RMSSD and PNN50)and frequency domain parameters(LF and HF)were significantly increased(P<0.05), frequency domain parameters(LF/HF)were significantly reduced(P<0.05)and the total incidence of cardiac complication were significantly reduced(18.4% or 7 cases vs.40.0% or 16 cases, P<0.05). Conclusions The HRV is decreased in patients with acute cerebral infarction.The reduction degree of HRV is more significant along with the higher NIHSS scores, which suggests that patients with high NIHSS scores are prone to an impairment of autonomic nerve function.For patients with high NIHSS scores after stroke, early drug intervention for regulating autonomic nerve function can effectively prevent the occurrence of cardiac emergencies and improve the prognosis of stroke. Key words: Cerebral infarction; Heart rate; Autonomic agents