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Effects of β-Adrenergic Blocking Therapy on Left Ventricular Diastolic Relaxation Properties in Patients With Dilated Cardiomyopathy

1999; Lippincott Williams & Wilkins; Volume: 100; Issue: 7 Linguagem: Inglês

10.1161/01.cir.100.7.729

1524-4539

Michael Kim, William Devlin, Sunil K. Das, Janet A. Petrusha, Daniel Montgomery, Mark R. Starling,

Cardiomyopathy and Myosin Studies

Background —The hemodynamic mechanism for the improvement in left ventricle (LV) end-diastolic pressure in cardiomyopathy patients treated with β-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, τ ln , shortened ( P =0.03). In a similar fashion, the LV chamber stiffness constant, κ, decreased ( P =0.02), LV volume elastance improved ( P =0.04), and the myocardial stiffness constant, κ e , decreased ( P =0.02). A multiple regression analysis revealed that the decrease in LV end-diastolic pressure was indicative of significant improvements in τ ln and κ e with the relationship: LV end-diastolic pressure=−4.73+0.27 τ ln +0.54 κ 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.