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Decreased heart rate variability in patients with congestive heart failure and chronotropic incompetence
1Department of Cardiological Sciences, St. George's Hospital Medical School, London, United Kingdom.
Insights
Patients with congestive heart failure and chronotropic incompetence show reduced heart rate variability. This suggests abnormal autonomic nervous system influence on the heart in these individuals.
Area of Science:
- Cardiology
- Autonomic Nervous System Function
- Heart Failure Research
Background:
- Congestive heart failure (CHF) is a complex condition affecting cardiac function.
- Heart rate variability (HRV) is a non-invasive measure of autonomic nervous system (ANS) activity.
- Chronotropic incompetence (CI) is characterized by an inadequate heart rate response during exercise.
Purpose of the Study:
- To investigate heart rate variability in patients with congestive heart failure and chronotropic incompetence.
- To explore the relationship between chronotropic incompetence and autonomic dysfunction in CHF.
Main Methods:
- Studied 41 patients with CHF secondary to idiopathic dilated cardiomyopathy.
- Utilized treadmill exercise tests and 24-hour Holter ECG monitoring.
- Analyzed spectral HRV components (total, low, high frequency) and standard deviation of normal RR intervals (SDNN).
Main Results:
- Ten patients exhibited chronotropic incompetence.
- Patients with CI had significantly lower peak oxygen consumption.
- Total and low-frequency HRV components and SDNN were significantly reduced in patients with CI.
Conclusions:
- Significantly decreased heart rate variability in CHF patients with CI indicates potential abnormal autonomic influence.
- Chronotropic incompetence may be linked to altered cardiac autonomic regulation in heart failure.
Unlabelled:
Heart rate variability was studied in 41 patients (aged 48 +/- 12 years) with congestive heart failure secondary to idiopathic dilated cardiomyopathy. All patients underwent a treadmill exercise test and 24-hour Holter ECG monitoring. Chronotropic incompetence was defined as the failure to achieve > or = 80% of the predicted maximal heart rate response given by 220--age (years) at peak exercise. Spectral heart rate variability was analyzed from 24-hour Holter ECGs and was expressed as total (0.01-1.00 Hz), low (0.04-0.15 Hz), and high (0.15-0.40 Hz) frequency components. The standard deviation of all normal RR intervals (SDNN) was also computed. Chronotropic incompetence was observed in ten patients. Peak oxygen consumption was significantly lower in patients with chronotropic incompetence compared with those without chronotropic incompetence. The total (5.11 +/- 1.26 ln [ms2] vs 6.41 +/- 0.92 ln [ms2]; P = 0.009) and low (3.38 +/- 1.65 ln [ms2] vs 5.45 +/- 1.34 ln [ms2]; P = 0.003), but not the high (3.42 +/- 1.04 ln [ms2] vs 4.00 +/- 1.12 ln [ms2]; P = 0.249) frequency components of heart rate variability were significantly lower in patients with chronotropic incompetence, although there was no significant difference in mean heart rate (88 +/- 20 beats/min vs 86 +/- 15 beats/min; P = 0.831) or left ventricular ejection fraction (22% +/- 10% vs 24% +/- 10%; P = 0.619). SDNN was also significantly lower in patients with chronotropic incompetence compared with those without chronotropic incompetence (64 +/- 34 ms vs 102 +/- 37 ms; P = 0.030).
Conclusions:
The observation that heart rate variability is significantly decreased in patients with congestive heart failure who have chronotropic incompetence suggests that chronotropic incompetence may relate to an abnormal autonomic influence on the heart in these patients.