(Circulation. 1999;100:729-735.)
© 1999 American Heart Association, Inc.
Clinical Investigation and Reports |
Effects of ß-Adrenergic Blocking Therapy on Left Ventricular Diastolic Relaxation Properties in Patients With Dilated Cardiomyopathy
From the University of Michigan and Veterans Affairs Medical Centers, Ann Arbor.
Background—The hemodynamic mechanism for the improvement in left ventricle (LV) end-diastolic pressure in cardiomyopathy patients treated with ß-adrenergic blocking agents is controversial. We hypothesized that the salutary effect of this kind of therapy on LV end-diastolic pressure would be indicative of an improvement in late, passive diastolic relaxation properties.
Methods and Results—We studied 14
cardiomyopathy patients in normal sinus rhythm with
no arteriographic evidence of coronary artery disease and an LV
ejection fraction of 
40% by radionuclide angiography both before and
after 6 months of metoprolol therapy with simultaneous
micromanometry and biplane
cineventriculography. Four comparable patients
who were not treated with metoprolol were studied in a similar fashion
and served as control subjects. In those receiving metoprolol, LV
end-diastolic pressure decreased (P=0.001).
The isovolumic relaxation index, 
ln, shortened
(P=0.03). In a similar fashion, the LV chamber stiffness
constant, 
, decreased (P=0.02), LV volume elastance
improved (P=0.04), and the myocardial stiffness
constant, e, decreased (P=0.02). A
multiple regression analysis revealed that the decrease in LV
end-diastolic pressure was indicative of significant
improvements in ln and e with the
relationship: LV end-diastolic pressure=-4.73+0.27
ln+0.54 e (r=0.81,
P<0.0001). These LV diastolic relaxation
properties did not change or worsened in the control
cardiomyopathy patients.
Conclusions—We conclude that the decrease in LV end-diastolic pressure in cardiomyopathy patients treated with metoprolol is an indicator of improvement in LV diastolic properties resulting from more complete myocardial relaxation.
Key Words: ventricles • cardiomyopathy • diastole • receptors, adrenergic, beta
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