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[Correlation between cardiac autonomic activity and compromise of left ventricular function in dilated
1Philipps-Universität Marburg, Klinik für Innere Medizin und Kardiologie, Marburg. HoMarburg@AOL.com
Insights
Heart rate variability (HRV) and baroreflex sensitivity (BRS) show weak correlations with left ventricular ejection fraction in idiopathic dilated cardiomyopathy (IDC). These measures may independently predict sudden death in IDC patients.
Area of Science:
- Cardiology
- Autonomic Nervous System Research
Context:
- Cardiac autonomic activity assessment via heart rate variability (HRV) and baroreflex sensitivity (BRS) is increasingly accessible.
- Previous studies (e.g., ATRAMI) linked diminished HRV and BRS to poor outcomes post-myocardial infarction.
- Limited data exists on cardiac autonomic function in idiopathic dilated cardiomyopathy (IDC) compared to coronary disease.
Purpose:
- To assess HRV and BRS in patients with idiopathic dilated cardiomyopathy (IDC).
- To investigate the relationship between HRV, BRS, and left ventricular ejection fraction (LVEF) in IDC patients.
- To explore potential independent predictors of sudden death in IDC.
Summary:
- HRV and BRS were evaluated in 160 IDC patients with preserved sinus rhythm.
- Weak correlations were observed between HRV (SDNN) and LVEF (r=0.29, p<0.05), and between HRV and BRS (r=0.19, p<0.05).
- No significant correlation was found between BRS and LVEF (r=0.14).
Impact:
- Findings suggest HRV, BRS, and LVEF may be independent predictors of sudden death in IDC.
- The study highlights the need for further investigation into prognostic markers for IDC.
- Ongoing research (Marburg Cardiomyopathy Study) will further elucidate the prognostic value of these and other markers.
Abstract:
In recent years, evaluation of cardiac autonomic activity by means of heart rate variability (HRV) determination and baroreflex sensitivity (BRS) testing has become readily available. The results of the ATRAMI (Autonomic Tone and Reflexes After Myocardial Infarction) study showed that both diminished HRV and baro-reflex sensitivity are associated with poor outcome in patients after myocardial infarction. In contrast to patients with coronary disease little information is available concerning cardiac autonomic activity in idiopathic dilated cardiomyopathy (IDC). Therefore, HRV and BRS were assessed in 160 patients with IDC and preserved sinus rhythm in order to investigate the relationship between HRV, BRS, and left ventricular ejection fraction. Time domain indices of HRV were computed from 24-hour digital Holter recordings. BRS testing was performed using the noninvasive phenylephrine method. Mean standard deviation of all normal RR intervals (SDNN) of the whole study population was 112 +/- 46 ms. A well preserved HRV (SDNN > 105 ms) was found in 74 patients (46%), a moderately decreased HRV (SDNN 70-105 ms) in 59 patients (37%), and a severely decreased HRV (SDNN < 70 ms) in 27 patients (17%). Mean BRS was 7.5 +/- 5.0 ms/mm Hg. A well preserved BRS (> 6 ms/mm Hg) was present in 78 patients (57%), a moderately decreased BRS (3-6 ms/mm Hg) was present in 38 patients (28%), and a severely decreased BRS (< 3 ms/mm Hg) in 21 patients (15%). There was only a weak correlation between SDNN and BRS (r = 0.19; p < 0.05). A weak correlation was found for SDNN and left ventricular ejection fraction (r = 0.29; p < 0.05). There was no significant correlation between BRS and left ventricular ejection fraction (r = 0.14). In summary, there was only a weak correlation between the HRV, BRS, and left ventricular ejection fraction in patients with IDC suggesting that these 3 variables may be independent predictors of sudden death in IDC. The relative prognostic value of these variables and other potential risk predictors including the presence of arrhythmias on Holter, microvolt T wave alternans, QTc dispersion, and signal-averaged ECG is currently under investigation in a large prospective observational study (Marburg Cardiomyopathy Study (MACAS)) during 5-year follow-up at our institution.