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Effect of propranolol on left ventricular relaxation in hypertrophic cardiomyopathy: an echographic study
Insights
Propranolol improves left ventricular diastolic function in hypertrophic cardiomyopathy (HCM) patients. Echocardiography showed that increasing propranolol doses shortened the isovolumic relaxation time (IVRT), often normalizing it at higher dosages.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Diastolic abnormalities are common in hypertrophic cardiomyopathy (HCM).
- Left ventricular isovolumic relaxation time (IVRT) is a key indicator of diastolic function.
Purpose of the Study:
- To investigate the effect of propranolol on left ventricular isovolumic relaxation time (IVRT) in patients with hypertrophic cardiomyopathy.
- To compare IVRT in HCM patients with control groups (aortic stenosis and normal subjects).
Main Methods:
- Echocardiography was used to measure IVRT in 20 HCM patients, 10 aortic stenosis patients, and 10 normal subjects.
- HCM patients received increasing doses of propranolol (160 mg, 320 mg, 480 mg daily).
Main Results:
- Normal subjects had IVRT < 50 msec.
- Aortic stenosis (77 msec) and HCM (94 msec) patients showed significantly prolonged IVRT (p < 0.001).
- Propranolol treatment progressively shortened IVRT in HCM patients, often normalizing it to ≤ 50 msec at higher doses.
Conclusions:
- Left ventricular relaxation improves with propranolol treatment in HCM.
- The improvement is dose-dependent, with normalization frequently observed at high propranolol dosages.
- Propranolol may be beneficial in managing diastolic dysfunction in hypertrophic cardiomyopathy.
Abstract:
Many authors have shown that hypertrophic cardiomyopathy (HCM) is often associated with diastolic abnormalities. The purpose of this study was to determine the effect of propranolol on left ventricular isovolumic relaxation time (IVRT) measured by echocardiography in 20 patients with hypertrophic cardiomyopathy under basal conditions and under increasing doses of propranolol (160 mg, 320 mg, and 480 mg per day) and in two control groups, 10 patients with aortic stenosis, and 10 normal subjects. IVRT was less than 50 msec in all normal subjects, while it was always above this limit in aortic stenosis (77 msec +/- 8, p less than 0.001), and in hypertrophic cardiomyopathy (94 msec +/- 19, p less than 0.001), with also a significant difference between these two last groups (p less than 0.01). Under increasing doses of propranolol, relaxation time often shortens gradually until 50 msec or less. These results show an improvement in left ventricular relaxation dependent on the propranolol dosage and often a normalization at high dosages.