Could autonomic nervous system parameters be still helpful in identifying patients with left ventricular systolic dysfunction at the highest risk of all-cause mortality?

Abstract

Background: Autonomic imbalance is associated with poor prognosis of patients with systolic dysfunction. Most of the previous data were written several years ago and constituted to cardiovascular or arrhythmic mortality. The current treatment of these patients has improved substantially over the last decades, and thus, the population at risk of death may have altered as well. Consequently, data on high-risk patients with systolic dysfunction in the modern era are sparse and those from previous trials may no longer be applicable. The aim herein, was to verify whether well-known autonomic indicesbaroreflex sensitivity (BRS) and heart rate variability (HRV)-remain accurate predictors of mortality in patients with systolic dysfunction. Methods: Non-invasively obtained BRS and HRV were analyzed in 205 clinically stable patients with left ventricular ejection fraction (LVEF) ≤ 40%. 28 patients died within 28 ± 9 month follow-up. Results: Baroreflex sensitivity, low-frequency (LF) in normalized units, LF to high-frequency ratio and standard deviation of average R-R intervals were significantly associated with mortality; cutoff values of the highest discriminatory power for abovementioned parameters were ≤ 3.0 ms/mmHg, ≤ 41, ≤ 0.7 and ≤ 25 ms, respectively. In bivariate Cox analyses (adjusted for LVEF, New York Heart Association [NYHA] or absence of implantable cardioverter-defibrillator [ICD]) autonomic indices remain significant predictors of death. Conclusions: Baroreflex sensitivity and HRV-may still be helpful in identifying patients with left ventricular systolic dysfunction at the highest risk of all-cause mortality, independently of LVEF, NYHA class, and ICD implantation.

Baroreflex sensitivity but not microvolt T-wave alternans can predict major adverse cardiac events in ischemic heart failure

“…In the present study, it was shown in both uniand multivariate Cox analyses, the role of BRS in the prediction of MACE occurrence in patients with HF of ischemic origin and LVEF up to 50%. The pre-specified cut-off value for BRS (3 ms/mmHg) is consistent with the results acquired by other researchers, where BRS was determined by both invasive and non-invasive methods [3,4,19,27,28,47]. In the current study, patients with BRS below 3 ms/mmHg had a relative risk for MACE threefold higher than patients above the cut-off.…”

“…Previous investigations concerning MACE risk assessment among patients with coronary artery disease were dedicated to other well-known clinical parameters [ 25 , 26 ], which were also confirmed in the present study. The role of ANS indices and MTWA was previously proven for arrhythmic, cardiac and all-cause mortality [ 2 – 7 , 19 , 27 – 34 ], however not for MACE, which are common and relevant in this population [ 1 ]. Moreover, the vast majority of cited studies omitted patients with ejection fraction 40–50%, who have similarly poor prognosis [ 35 – 39 ].…”

“…Moreover, as Figure 3 presents, individuals with both LVEF ≤ 33% and BRS ≤ 3 ms/mmHg had the highest MACE probability over a 34-month follow-up period. In many previous studies, BRS was proved to have prognostic value in predicting various end-points, such as hospitalization due to HF exacerbation as well as arrhythmic, cardiovascular, or all-cause mortality [ 3 , 4 , 8 , 19 , 27 , 28 , 47 ]. The results of our research show that BRS also has an important role in the prediction of MACE, which proves the fact that autonomic imbalance could have an enormous impact on the development of various cardiovascular complications, and that this parameter should be taken into account in risk stratification and clinical evaluation of HF patients.…”