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Xamoterol in hypertrophic cardiomyopathy: effects on diastolic function and heart rate
D M Gilligan1, R Stewart, W L Chan
1Department of Medicine (Clinical Cardiology), Royal Postgraduate Medical School, Hammersmith Hospital, London, UK.
Insights
Xamoterol, a beta-1 adrenergic agonist, stabilizes heart rate in hypertrophic cardiomyopathy patients. While not impacting Doppler measurements, it warrants further investigation for potential diastolic function benefits.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Hypertrophic cardiomyopathy (HCM) is a genetic heart muscle disease.
- Diastolic dysfunction is a common complication of HCM.
- Ambulatory heart rate management is crucial in HCM patients.
Purpose of the Study:
- To evaluate the effects of xamoterol on diastolic function and heart rate in patients with non-obstructive hypertrophic cardiomyopathy.
- To assess xamoterol's potential as a therapeutic agent for HCM.
Main Methods:
- Cross-sectional and Doppler echocardiography were used to assess left ventricular function.
- 24-hour Holter monitoring was employed to evaluate ambulatory heart rate.
- Eleven patients with non-obstructive HCM received a single intravenous dose of xamoterol.
Main Results:
- Xamoterol administration led to a significant increase in resting heart rate (76 to 83 bpm).
- Maximum heart rate decreased (127 to 112 bpm) and minimum heart rate increased (60 to 67 bpm) in the 4-hour post-dose period.
- No significant changes were observed in echocardiographic measurements of left ventricular function.
Conclusions:
- Xamoterol demonstrates a heart rate-stabilizing effect in hypertrophic cardiomyopathy.
- The lack of significant Doppler changes does not rule out potential benefits for diastolic function.
- Further research into xamoterol as a novel therapy for HCM is recommended.
Abstract:
The aims of this study were to determine the effects of the partial beta 1-adrenergic agonist, xamoterol, on diastolic function and ambulatory heart rate in hypertrophic cardiomyopathy. Eleven patients with non-obstructive hypertrophic cardiomyopathy were studied with cross-sectional and Doppler echocardiography and 24-h Holter monitoring before and after a single intravenous dose of xamoterol. Resting heart rate (mean +/- SD) increased from 76 +/- 16 before, to 83 +/- 15 beats/min 15 min after xamoterol, p = 0.03. In the 4-h period after xamoterol, maximum heart rate was reduced (127 +/- 21 to 112 +/- 19, p = 0.01) and minimum heart increased (60 +/- 16 to 67 +/- 17, p = 0.04) compared to the same 4-h period of the previous day. There were no significant changes in cross-sectional or Doppler echocardiographic measurements of left ventricular function following xamoterol. Xamoterol stabilises the heart rate in hypertrophic cardiomyopathy. The absence of a significant effect on Doppler measurements does not preclude a beneficial effect on diastolic function. This initial study suggests that xamoterol should be further investigated as a new medical therapy for hypertrophic cardiomyopathy.