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Baroreflex sensitivity and heart rate variability in coronary disease compared to dilated cardiomyopathy
1Department of Cardiology, Philipps-University of Marburg, Germany.
Insights
Cardiac autonomic tone is comparable in patients with coronary artery disease (CAD) and idiopathic dilated cardiomyopathy (IDC) when left ventricular ejection fraction is severely depressed. However, CAD patients with preserved function show reduced heart rate variability compared to IDC patients.
Area of Science:
- Cardiology
- Autonomic Nervous System Research
- Cardiovascular Disease
Background:
- Cardiac autonomic dysfunction is a significant factor in cardiovascular diseases.
- Baroreceptor sensitivity and heart rate variability are key indicators of autonomic tone.
- Coronary artery disease (CAD) and idiopathic dilated cardiomyopathy (IDC) present distinct pathophysiological pathways but can lead to similar clinical outcomes.
Purpose of the Study:
- To compare baroreceptor sensitivity and heart rate variability as measures of cardiac autonomic tone in patients with CAD and IDC.
- To investigate the influence of left ventricular ejection fraction (LVEF) on these autonomic measures in both patient groups.
Main Methods:
- 24-hour Holter ECG was used to determine time-domain heart rate variability (SDNN, SDANN, pNN50).
- Noninvasive phenylephrine method was employed to analyze baroreflex sensitivity.
- Patients were stratified based on LVEF (< or = 30% vs. > 30%) for subgroup analysis.
Main Results:
- Baroreflex sensitivity and heart rate variability were comparable between CAD and IDC patients overall.
- Subgroup analysis of patients with LVEF < or = 30% revealed no significant differences in autonomic measures between CAD and IDC.
- Patients with CAD and LVEF > 30% exhibited decreased heart rate variability compared to IDC patients with preserved LVEF (P < 0.05 for SDNN, SDANN, pNN50).
Conclusions:
- Markedly depressed LVEF leads to comparable alterations in cardiac autonomic tone in both CAD and IDC.
- CAD patients with preserved LV function demonstrate reduced heart rate variability, suggesting a specific autonomic alteration not seen in IDC patients with preserved function.
- Prospective studies in a larger cohort are needed to determine the prognostic significance of these findings.
Abstract:
This study was designed to compare baroreceptor sensitivity and heart rate variability as measures of cardiac autonomic tone in patients with coronary disease (CAD, n = 49) and idiopathic dilated cardiomyopathy (IDC, n = 130). Time domain heart rate variability, including SDNN, SDANN, and pNN50, was determined during 24-hour Holter ECG. Baroreflex sensitivity was analyzed nonivasively using the phenylephrine method. Baroreflex sensitivity and heart rate variability were comparable between patients with CAD versus IDC (baroreflex sensitivity: 6.1 +/- 3 vs 6.9 +/- 5 ms/mmHg; SDNN: 97 +/- 40 vs 114 +/- 41 ms; SDANN: 83 +/- 33 vs 99 +/- 41 ms; pNN50: 3.9 +/- 4 vs 9.6 +/- 13 ms, P = NS for all comparisons). Likewise, a subgroup analysis of patients with a left ventricular ejection fraction (LVEF) < or = 30% showed no significant difference in baroreceptor sensitivity and heart rate variability between IDC and CAD patients. Patients with CAD and an LVEF > 30% had a decreased heart rate variability but not a decreased baroreflex sensitivity compared to patients with IDC and LVEF > 30% (baroreflex sensitivity: 6.4 +/- 4 vs 8.3 +/- 6 ms/mmHg, P = NS; SDNN: 98 +/- 19 vs 128 +/- 42 ms, P < 0.05; SDANN: 86 +/- 21 vs 112 +/- 43 ms, P < 0.05; pNN50: 4.2 +/- 3 vs 12.3 +/- 8 ms, P < 0.05). Patients with a markedly depressed LVEF show comparable alterations in cardiac autonomic tone whether they have CAD or IDC. Patients with CAD and preserved LV function, however, have a decreased heart rate variability compared to patients with IDC and preserved LV function. The prognostic significance of these findings will be determined prospectively in a large patient cohort at our institution.