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Cardiac parasympathetic activity in severe uncomplicated coronary artery disease
1University Department of Medicine, Royal Infirmary, Edinburgh.
Insights
This study found no evidence linking coronary artery disease to reduced cardiac parasympathetic activity in uncomplicated cases. Previous findings may be due to patient complications, not the disease itself.
Area of Science:
- Cardiology
- Autonomic Nervous System Research
- Medical Pathophysiology
Background:
- Previous research suggested a link between coronary artery disease and reduced cardiac parasympathetic activity.
- These studies often included patients with complications that could confound autonomic function findings.
Purpose of the Study:
- To investigate cardiac parasympathetic activity in patients with severe, uncomplicated coronary artery disease.
- To determine if coronary artery disease independently affects parasympathetic function.
Main Methods:
- Studied 44 patients with severe coronary artery disease but no complications (infarction, diabetes, hypertension).
- Measured cardiac parasympathetic activity using 24-hour ambulatory electrocardiograms to assess heart rate variability.
- Utilized a validated index based on successive RR interval differences (> 50 ms) to quantify parasympathetic activity.
Main Results:
- Mean heart rate variability counts were within normal ranges for waking, sleeping, and 24-hour periods.
- Fewer than 10% of patients showed reduced parasympathetic activity compared to normal controls.
- No correlation was found between coronary artery disease severity, antianginal drug use, and cardiac parasympathetic activity.
Conclusions:
- This study found no independent association between uncomplicated coronary artery disease and reduced cardiac parasympathetic activity.
- The findings suggest that previously reported autonomic abnormalities may be linked to complications rather than coronary artery disease itself.
Background:
Previous studies have suggested that coronary artery disease is independently associated with reduced cardiac parasympathetic activity, and that this is important in its pathophysiology. These studies included many patients with complications that might be responsible for the reported autonomic abnormalities.
Objective:
To measure cardiac parasympathetic activity in patients with uncomplicated coronary artery disease.
Patients And Methods:
44 patients of mean (SD) age 56 (8) with severe uncomplicated coronary artery disease (symptoms uncontrolled on maximal medical treatment; > 70% coronary stenosis at angiography; normal ejection fraction; no evidence of previous infarction, diabetes, or hypertension). Heart rate variability was measured from 24 hour ambulatory electrocardiograms by counting the number of times successive RR intervals exceeded the preceding RR interval by > 50 ms, a previously validated sensitive and specific index of cardiac parasympathetic activity.
Results:
Mean (range) of counts were: waking 112 (range 6-501)/h, sleeping 198 (0-812)/h, and total 3912 (151-14 454)/24 h. These mean results were unremarkable, and < 10% of patients fell below the lower 95% confidence interval for waking, sleeping, or total 24 hour counts in normal people. There was no relation between the severity of coronary artery disease or the use of concurrent antianginal drug treatment and cardiac parasympathetic activity.
Conclusion:
In contrast with previous reports no evidence of a specific independent association between coronary artery disease and reduced cardiac parasympathetic activity was found. The results of previous studies may reflect the inclusion of patients with complications and not the direct effect of coronary artery disease itself.
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