carbon-11-acetate and Heart-Failure

Cardiac resynchronization therapy (CRT) is a treatment option in patients with severe heart failure and left bundle-branch block (LBBB). This study evaluated the effects of 4 and 13 mo of CRT on myocardial oxygen consumption (MVO2) and cardiac efficiency as compared with mild heart failure patients without LBBB.. Sixteen patients with severe heart failure and LBBB due to idiopathic cardiomyopathy were studied at baseline and after 4 and after 13 mo of therapy. Thirteen patients with mild heart failure without LBBB served as a comparison group. The clearance rate (k2) of 11C-acetate was measured with PET to assess MVO2. Stroke volume was derived from the dynamic PET data according to the Stewart-Hamilton principle and, furthermore, cardiac efficiency using the work metabolic index.. After 4 mo of CRT, stroke volume index (SVI) increased by 50% (P = 0.012) and cardiac efficiency increased by 41% (P < 0.001). Global k2 remained unchanged but regional k2 demonstrated a more homogeneous distribution pattern. The parameters showed no significant changes during therapy. Under CRT, cardiac efficiency, SVI, and the distribution pattern of regional k2 did not differ from mild heart failure patients without LBBB.. CRT improves cardiac efficiency for at least 13 mo, as demonstrated by a higher SVI, whereas MVO2 remains unchanged. Cardiac efficiency, SVI, and the MVO2 distribution pattern reach the level of patients with mild heart failure without LBBB. The unfavorable hemodynamic performance in heart failure with LBBB is effectively restored by long-term CRT to the level of an earlier disease state.

Topics: Acetates; Adolescent; Adult; Aged; Bundle-Branch Block; Carbon; Cardiac Output; Cardiac Pacing, Artificial; Female; Heart Failure; Humans; Longitudinal Studies; Male; Middle Aged; Oxygen Consumption; Positron-Emission Tomography; Radiopharmaceuticals; Recovery of Function; Treatment Outcome

The purpose of this study was to examine the usefulness of (11)C-acetate positron emission tomography (PET) for assessing the efficacy of cardiac resynchronization therapy (CRT). Enrolled in this study were 20 patients with severe heart failure. All patients underwent 11C-acetate PET within 1 week after CRT. The oxygen consumption was measured by the monoexponential clearance rate of 11C-acetate (K(mono)) for both CRT-off and -on. Cardiac efficiency (CE) was determined using the concept of the work metabolic index (WMI). WMI was calculated as WMI = (stroke volume index) x (systolic blood pressure) x (heart rate)/K(mono). The patients were divided into two groups: 14 patients with improved CE (from 5.27 +/- 0.91 to 6.77 +/- 1.12) and 6 patients with deteriorated CE (from 5.35 +/- 0.92 to 4.86 +/- 0.84) by CRT-on. K(mono) decreased from 0.053 +/- 0.006 to 0.046 +/- 0.003 by CRT-on in the improved CE group (p = 0.028), but increased from 0.049 +/- 0.006 to 0.050 +/- 0.006 in the deteriorated-CE group (p = 0.036). Stroke volume index, systolic blood pressure, and heart rate did not change by CRT-on for either group. At the one-year follow-up, there were significantly higher rates of major cardiac adverse events in the deteriorated-CE group than in the improved-CE group (p = 0.032). Therefore, the improvement of CE, as assessed by 11C-acetate PET in the early period after CRT, is produced by the decrease in oxygen consumption in patients showing good responses to CRT. The decrease in oxygen consumption in the early period after CRT is thus a useful marker for predicting a good clinical outcome after CRT.

Topics: Acetates; Aged; Aged, 80 and over; Blood Pressure; Carbon; Cardiac Pacing, Artificial; Chi-Square Distribution; Disease-Free Survival; Echocardiography, Doppler; Energy Metabolism; Female; Heart Failure; Heart Rate; Humans; Kaplan-Meier Estimate; Male; Middle Aged; Myocardium; Oxygen Consumption; Positron-Emission Tomography; Predictive Value of Tests; Radiopharmaceuticals; Recovery of Function; Severity of Illness Index; Stroke Volume; Time Factors; Treatment Outcome

Topics: Acetates; Carbon; Cardiac Pacing, Artificial; Disease-Free Survival; Echocardiography, Doppler; Energy Metabolism; Heart Failure; Hemodynamics; Humans; Myocardium; Oxygen Consumption; Positron-Emission Tomography; Predictive Value of Tests; Radiopharmaceuticals; Recovery of Function; Severity of Illness Index; Time Factors; Treatment Outcome

A 70-year-old woman with dilated cardiomyopathy and recurrent severe heart failure was admitted for biventricular pacing (BVP), which was recently reported to have clinical efficacy for severe heart failure with intraventricular conduction delay. An electrocardiogram showed complete left bundle branch block, and the QRS interval was markedly prolonged at 195 msec. Echocardiogram showed marked dilatation, diffuse hypokinesis and dyssynchrony of the left ventricle, and grade III mitral valve regurgitation. The patient underwent implantation of an atriobiventricular pacemaker and three pacing leads transvenously. The QRS interval shortened to 165 msec immediately after the BVP therapy, and improvements in echocardiographic parameters were seen at 5 months after BVP therapy. Myocardial oxidative metabolism was assessed by the monoexponential clearance rate of [11C]acetate (Kmono) as measured by positron emission tomography (PET), and myocardial efficiency was assessed by the work metabolic index (WMI) at 1 and 5 months after the BVP therapy. The PET images obtained 5 months after BVP therapy showed a decrease in the clearance of [11C]acetate compared with that obtained 1 month after BVP therapy. The Kmono of the whole left ventricle decreased from 0.051 at 1 month to 0.038 min-1 at 5 months after BVP therapy, and that of the septum, anterior wall, lateral wall and posterior wall also decreased. The WMI increased from 4.2 x 10(6) to 6.8 x 10(6) mmHg. ml/m2. These results suggest that BVP improved left ventricular function without increasing myocardial oxidative metabolism, resulting in improved myocardial efficiency, and that BVP may improve the long-term prognosis of heart failure patients with ventricular dyssynchrony. [11C]acetate PET is a useful method of evaluating global and regional myocardial oxidative metabolism in patients who have undergone BVP therapy.

Topics: Acetates; Aged; Carbon; Cardiac Pacing, Artificial; Female; Heart; Heart Failure; Humans; Myocardium; Oxygen; Radionuclide Imaging; Radiopharmaceuticals; Treatment Outcome; Ventricular Dysfunction, Left