IntroductionAutonomic nervous system balance can be significantly deteriorated during heart failure exacerbation. However, it is still unknown whether these changes are only the consequence of heart failure decompensation or can also predict development thereof. Objectives were to verify if simple, non-invasive autonomic parameters, such as baroreflex sensitivity and short-term heart rate variability can provide independent of other well-known clinical parameters information on the risk of heart failure decompensation in patients with left ventricular systolic dysfunction.MethodsIn 142 stable patients with left ventricular ejection fraction ≤ 40%, baroreflex sensitivity and short-term heart rate variability, as well as other well-known clinical parameters, were analyzed. During 23 ± 9 months of follow-up 19 patients were hospitalized due to the heart failure decompensation (EVENT).ResultsPre-specified cut-off values of baroreflex sensitivity (≤2.4 ms/mmHg) and low frequency power index of heart rate variability (≤19 ms2) were significantly associated with the EVENTs (hazard ratio 4.43, 95% confidence interval [CI] 1.35–14.54 and 5.41, 95% CI 1.87–15.65 respectively). EVENTs were also associated with other parameters, such as left ventricular ejection fraction, NYHA class, diuretic use, renal function, brain natriuretic peptide and hemoglobin level, left atrial size, left and right ventricular heart failure signs. After adjusting baroreflex sensitivity and low frequency power index for each of the abovementioned parameters, autonomic parameters were still significant predictors of hospitalization due to the heart failure decompensation.ConclusionSimple, noninvasive autonomic indices can be helpful in identifying individuals with increased risk of hospitalization due to the heart failure decompensation among clinically stable patients with left ventricular systolic dysfunction, even when adjusted for other well-known clinical parameters.
In the group of patients with left ventricular systolic dysfunction, excluding patients with a history of malignant ventricular arrhythmia, the NPV of MTWA was 100% over 12 months of observation. MTWA may therefore be considered useful in determining the order of ICD implantation procedures in this group of patients by identifying patients at a relatively low risk of malignant ventricular arrhythmias, who can be relatively safely rescheduled for ICD implantation at a later time. Future studies should concentrate on this issue.
The improvement in autonomic nervous system activity after successful CTO recanalisation is reflected by an increase in BRS, and the changes are dependent on the baseline value of the measurement: patients with a depressed BRS before recanalisation present a greater BRS improvement than patients with a preserved BRS. The CTO recanalisation leads to the improvement of LVEF in both groups.
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