Dobutamine stress 99mTc-tetrofosmin quantitative gated SPECT predicts improvement of cardiac function after carvedilol treatment in patients with dilated cardiomyopathy.

Abstract

We evaluated whether dobutamine stress (99m)Tc-tetrofosmin quantitative gated SPECT (D-QGS) could predict improvement of cardiac function by carvedilol therapy in patients with dilated cardiomyopathy (DCM). The study included 30 patients with idiopathic DCM and a left ventricular ejection fraction (LVEF) of <45%. D-QGS was performed in all patients to measure LVEF at rest and during dobutamine infusion (10 microg/kg/min). LVEF and left ventricular end-diastolic volume (LVEDV) were determined by echocardiography, plasma brain natriuretic peptide (BNP) was measured, and the New York Heart Association (NYHA) functional class was estimated at baseline and after 1 y of combined treatment with an angiotensin-converting enzyme (ACE) inhibitor, diuretic, and the beta-blocker carvedilol. After treatment, the echocardiographic LVEF improved by >5% in 15 patients (group A) but did not improve in the remaining 15 patients (group B). The baseline LVEF, LVEDV, plasma BNP, and NYHA functional class were similar in both groups. However, there was a greater increase of LVEF (Delta LVEF) with dobutamine infusion during D-QGS in group A than that in group B (12.0% +/- 5.8% vs. 2.7% +/- 4.2%, P < 0.0001). When a cutoff value of 6.6% for Delta LVEF was used to predict the improvement of LVEF by carvedilol therapy, the sensitivity was 86.7%, the specificity was 86.7%, and the accuracy was 86.7%. LVEDV, plasma BNP, and NYHA functional class all showed superior improvement in group A compared with group B. Delta LVEF measured by D-QGS was significantly larger in patients who responded to carvedilol than that in nonresponders. These findings indicate that D-QGS can be used to predict improvement of cardiac function and heart failure symptoms by carvedilol therapy in patients with idiopathic DCM.