Myocardial Contractile Reserve by Dobutamine Stress Echocardiography Predicts Improvement in Ejection Fraction With β-Blockade in Patients With Heart Failure

Abstract

MS; for the BEST InvestigatorsBackground-␤-Blockers improve survival and reduce hospitalization in chronic heart failure (CHF) by biologically improving left ventricular ejection fraction (LVEF). However, a good predictor of improvement with this therapy has not been identified. This substudy of BEST examined whether myocardial contractile reserve, as determined by dobutamine stress echocardiography, predicts improvement in LVEF. Methods and Results-Seventy-nine patients with class III/IV CHF underwent dobutamine stress echocardiography before treatment with bucindolol (nϭ41) or placebo (nϭ38). Regional wall motion score index (WMSI) was calculated as the sum of the scores in each segment divided by the total number of segments visualized. WMSI was compared with change in LVEF after 3 months of therapy as determined by gated radionuclide scan. Change in WMSI correlated inversely with change in LVEF after 3 months of bucindolol (rϭϪ0.72, PϽ0.0001) and was the most significant multivariate predictor of change in LVEF (Pϭ0.0002). Patients with contractile reserve had demographics similar to those of patients without contractile reserve, including RVEF, LVEF, systolic blood pressure, and CHF duration. However, patients without contractile reserve had higher baseline plasma norepinephrine levels (687Ϯ333 versus 420Ϯ246 pg/mL, PϽ0.05) and greater decrease in plasma norepinephrine in response to bucindolol (Ϫ249Ϯ171 versus Ϫ35Ϯ277 pg/mL, PϽ0.05). Conclusions-This study suggests a direct relationship between contractile reserve and improvement in LVEF with ␤-blocker therapy in patients with advanced CHF. Patients without contractile reserve have higher resting adrenergic drive, as reflected by plasma norepinephrine, and may experience greater sympatholytic effects from bucindolol.

Myocardial β-Adrenergic Receptor Density Assessed by 11C-CGP12177 PET Predicts Improvement of Cardiac Function After Carvedilol Treatment in Patients with Idiopathic Dilated Cardiomyopathy

“…The present study could not confirm previous results (6,7) showing that cardiac contractile reserve during dobu- tamine stress is useful for predicting the efficacy of b-blockers in patients with IDC and heart failure. There are several explanations for this discrepancy.…”

“…These factors might explain the failure of DLVEF-dobutamine to demonstrate a relationship to DLVEF-carvedilol. However, a low-dosage infusion protocol (10-20 mg of dobutamine per kilogram per minute) has been established to evaluate contractile reserve in previous studies (6,7).…”

“…b-blockers exert their benefits at least in part by inhibiting sympathetically mediated myocardial damage and necrosis (3,5). Previous studies have reported that cardiac contractile reserve during dobutamine stress predicts the improvement of cardiac function with b-blocker therapy in patients with idiopathic dilated cardiomyopathy (IDC) (6,7). However, it is generally still difficult to predict whether heart failure patients will respond favorably to b-blockers.…”

Dobutamine stress for evaluation of right ventricular reserve in pulmonary arterial hypertension

“…Inotropic stimulation with dobutamine is an accepted alternative to exercise stress in the evaluation of left ventricular contractile reserve across a range of underlying pathologies including ischaemic heart disease, idiopathic dilated cardiomyopathy and valvular heart disease [8][9][10]. In contrast, only limited studies have addressed RV contractile reserve and these have predominantly been in the setting of biventricular failure [7,[11][12][13][14][15][16][17].…”

Dobutamine-Induced Improvement in Inferior Myocardial Contractile Function Predicts Reduction in Functional Mitral Regurgitation

“…Dobutamine detects myocardial contractile reserve 21,22 ; on the other hand, exercise predicts global cardiac capacity with increased LV preload and afterload. 13 It has been shown that exercise stress increases FMR 7,12,13 because it (1) increases the LV preload due to increased venous return, (2) increases systemic vascular resistance in conjunction with the autonomic nervous system, (3) causes an increase in LV sphericity, 12 and (4) dilates the MA.…”