The correlation between frailty and cardiac autonomic nervous function in elderly patients / 中华老年医学杂志

ABSTRACT

Objective:To assess the correlation between frailty and cardiac autonomic nervous system function in elderly patients.Methods:Elderly hospitalized patients aged 65 years and over were enrolled and assessed for frailty by using the clinical frailty scale.Cardiac autonomic modulation was evaluated by heart rate variability analysis through 24 h electrocardiogram recording.Results:A total of 180 elderly patients were enrolled in this study, including 66 patients with frailty and 114 patients without frailty.The mean age of the frailty group was higher than that of the non-frailty group(79.8±6.0 vs.75.0±6.3, t=5.030, P<0.001). The proportions of patients with hypertension, stroke/transient cerebral ischemia attack(TIA), heart failure and osteoarthritis were higher in the frailty group than in the non-frailty group(all P<0.05). Compared with the non-frailty group, the standard deviation of normal-to-normal intervals(SDNN)[103.0(76.0, 121.2) vs.107.5(92.0, 136.0), Z=-2.108, P=0.035], the standard deviation of the averages of NN intervals in all 5-min segments(SDANN)[86.0(67.7, 106.5) vs.97.5(78.0, 126.0), Z=-2.694, P=0.007], normalized low frequency(LFnorm)(53.1±13.0 vs.59.3±13.9, t=-3.024, P=0.003)and low frequency/high frequency(LF/HF)ratio[1.2(1.0, 1.4) vs.1.4(1.1, 1.7), Z=-3.041, P=0.002]were decreased and normalized high frequency(HFnorm)(36.8±9.2 vs.32.2±10.7, t=3.033, P=0.003)was increased in the frailty group.HFnorm in the frailty group was significantly higher than that in the non-frailty group.The incidents of SDANN<92 ms, LFnorm<50 nU, HFnorm>32 nU and LF/HF ratio<1.5 were higher in the frailty group than in the non-frailty group(59.1% or 39/66 vs.41.2% or 47/114, 42.4% or 28/66 vs.22.8% or 26/114, 72.7% or 48/66 vs.49.1% or 56/114, 84.8% or 56/66 vs.65.8% or 75/114, χ2=5.346, 7.660, 9.547, 7.664, P=0.021, 0.006, 0.002, 0.006). Logistic multivariate regression analysis showed that LFnorm, HFnorm and LF/HF ratio were correlated with frailty( OR=0.971, 1.039 and 0.333, all P<0.05), and HFnorm>32 nU and LF/HF ratio<1.5 were risk factors for frailty( OR=2.401 and 2.773, both P<0.05). Conclusions:Cardiac autonomic nerve system function is impaired in elderly frail patients, with the imbalance between the sympathetic and vagus nerves.Therefore particular attention should be paid to heart rate variability in elderly patients with frailty.