Can power spectral analysis of heart rate variability identify a high risk subgroup of congestive heart failure patients with excessive sympathetic activation? A pilot study before and after heart transplantation.

Abstract

Background and objectives-Autonomic dysfunction seems to be involved in the progression and prognosis of severe congestive heart failure. Parasympathetic activity can still be abnormal 4-8 weeks after haemodynamic improvement by heart transplantation. To identify patients in heart failure with a more pronounced neural derangement and to analyse the changes in sympathetic and parasympathetic activity soon after heart transplantation, spectral indices of heart rate variability were assessed in 30 patients in severe heart failure and in 13 patients after heart transplantation; a group of 15 age-matched subjects served as controls. Methods and results-Heart rate variability was assessed by standard electrocardiography (ECG) in patients in heart failure and by oesophageal ECG in patients after heart transplantation. Compared with controls, the mean RR interval and total power were reduced in heart failure. The 30 patients showed two different patterns of heart rate variability: in 14 no power was detected in the low frequency band (0.03-0.15 Hz) (LF) and total power was mainly concentrated in the high frequency band (0.15-0-45 Hz) (HF), whereas in the remaining 16 patients power in the LF band was increased and power in HF band was reduced compared with the controls. Patients with undetectable LF had a lower mean RR interval and total power (745 (25) Conclusions-These data suggest that in more advanced stages of congestive heart failure, power spectral analysis of heart rate variability allows identification of a subgroup of patients with higher sympathetic activation and poorer clinical status who are at major risk of adverse events. In the short term after cardiac transplantation the spectral profile of the rhythm variability of the remnant atrium was not improved, suggesting that parasympathetic withdrawal and sympathetic hyperactivity persist, despite the restoration of ventricular function. (Br Heart J7 1994;71:422-430) Heart failure in both experimental and clinical settings is associated with considerable neurohumoral excitation, resulting in abnormal autonomic control of cardiovascular function. Increased sympathetic activity and plasma concentrations of noradrenaline.' 2 parasympathetic withdrawal,3-5 and impaired baroreflex gain68 have been reported. This excessive neurohumoral activation is involved in progression of heart failure and in prognosis.Analysis of heart rate variability is regarded a valid technique to assess non-invasively the sympathovagal balance of the heart. Frequency domain analysis of heart rate fluctuations identifies the relative influence of the two neural limbs that regulate heart rhythm. In our present study we tested the hypothesis that power spectrum analysis of heart rate variability in congestive heart failure may identify patients with a more pronounced

Prognostic factors in patients with congestive heart failure

“…The authors suggest that HRV is superior to other prognostic factors, such as EF, pulmonary capillary pressure, cardiac index, and serum sodium. Mortara et al 149 , studying patients before and just after heart transplantation, found similar results.…”

“…In patients with CHF, the HRV is greatly reduced, reflecting sympathetic hyperactivity and reduction of vagal activity, correlating with the severity of the disease [148][149][150] . Several authors found correlation between HRV, LVEF 148,150 , and also the plasmatic level of noradrenaline 149,151 . Kienzle et al 151 did not find correlation between HRV and EF or FC.…”

“…In the last five years, HRV has been shown to of important prognostic value in CHF 149,[152][153][154] . Despite the small number of patients in the series, the largest consisting of 102 patients 153 , the results have been consistent.…”

Prognostic Value of the Change in Heart Rate From the Supine to the Upright Position in Patients With Chronic Heart Failure

“…We have not demonstrated how well ΔHR reflects established measures of autonomic tone in HF, including HR variability,4 HR recovery,3 norepinephrine spillover,2 baroreflex sensitivity, or muscle sympathetic nerve activity 8. Further studies will be required to better define the pathophysiological correlates of ΔHR.…”

“…Measures of more advanced autonomic dysfunction are indicators of the severity of HF and adverse prognosis 2, 3, 4, 5, 6. They may include heart rate variability,4, 7 heart rate recovery,3 baroreflex sensitivity,5 measurement of norepinephrine spillover,2, 7 and muscle nerve sympathetic activity 8. However, the techniques needed to identify these are complex, and their application requires considerable infrastructure and time and are, therefore, not well suited for serial testing in clinical practice.…”