Tissue doppler imaging predicts improved systolic performance and reversed left ventricular remodeling during long-term cardiac resynchronization therapy

AbstractObjectivesWe sought to evaluate the long-term impact of cardiac resynchronization therapy (CRT) on left ventricular (LV) performance and remodeling using three-dimensional echocardiography and tissue Doppler imaging (TDI).BackgroundThree-dimensional echocardiography and TDI allow rapid and accurate evaluation of LV volumes and performance.MethodsTwenty-five consecutive patients with severe heart failure and bundle branch block who underwent biventricular pacemaker implantation were included. Before and after implantation of the pacemaker, three-dimensional echocardiography and TDI were performed. These examinations were repeated at outpatient visits every six months.ResultsFive patients (20%) died during one-year follow-up. In the remaining 20 patients, significant reductions in LV end-diastolic volume and LV end-systolic volume of 9.6 ± 14% and 16.5 ± 15%, respectively (p < 0.01), could be demonstrated during long-term follow-up. Accordingly, LV ejection fraction increased by 21.7 ± 18% (p < 0.01). According to a newly developed TDI technique—tissue tracking—all regional myocardial segments improved their longitudinal systolic shortening (p < 0.01). The extent of the LV base displaying delayed longitudinal contraction, as detected by TDI before pacemaker implantation, predicted long-term efficacy of CRT. The QRS duration failed to predict resynchronization efficacy.ConclusionsCardiac resynchronization significantly improved LV function and reversed LV remodeling during long-term follow-up. Patients likely to benefit from CRT can be identified by TDI before implantation of a biventricular pacemaker

Energy stores and metabolites in chronic reversibly and irreversibly dysfunctional myocardium in humans

AbstractOBJECTIVESOur goal was to study metabolic energy stores and lactate content in chronic reversibly and irreversibly dysfunctional myocardium.BACKGROUNDIt is unknown whether metabolism is deranged in chronic reversibly and irreversibly dysfunctional myocardium in humans. Semiquantitative histological examinations have shown altered mitochondrial morphology and glycogen accumulation in dysfunctional regions.METHODSWe studied 25 patients with a mean ejection fraction of 38 ± 9% scheduled for coronary artery bypass surgery. Regional perfusion and metabolism were assessed by positron emission tomography, and regional function was assessed by echocardiography. Perioperative myocardial biopsies were obtained from a control region and from a dysfunctional region. We analyzed biopsies for contents of noncollagen protein (NCP), ATP, ADP, AMP, glycogen and lactate. Six months after surgery we assessed wall motion by echocardiography to group patients in those with (n = 11) and without (n = 14) functional improvement.RESULTSReversibly dysfunctional myocardium had reduced perfusion (0.59 ± 0.16 vs. 0.69 ± 0.20 ml/g/min, p < 0.05), similar glucose-tracer uptake (92 ± 12 and 95 ± 14%), ATP/ADP ratio (2.4 ± 1.1 and 2.4 ± 0.7), glycogen content (631 ± 174 and 632 ± 148 nmol/μg NCP) and lactate levels (59 ± 27 and 52 ± 29 nmol/μg NCP) compared with control regions. Irreversibly dysfunctional regions (n = 14) had severely reduced perfusion (0.48 ± 0.15 vs. 0.72 ± 0.12 ml/g/min, p < 0.001) and glucose-tracer uptake (52 ± 16 vs. 94 ± 15%, p < 0.001), reduced ATP/ADP ratio (1.5 ± 0.9 vs. 2.3 ± 0.9, p < 0.05), similar glycogen content (579 ± 265 vs. 593 ± 127 nmol/μg NCP) and increased lactate levels (114 ± 52 vs. 89 ± 24 nmol/μg NCP, p < 0.01) compared with control regions.CONCLUSIONSContents of metabolic energy stores and lactate in chronic reversibly dysfunctional myocardium were preserved. In contrast, energy stores were depleted in myocardium without functional recovery after revascularization