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Aims Experimental studies indicated unfavourable effects on myocardial energetics and efficiency under asynchronous ventricular stimulation, also shown for left bundle branch block (LBBB) pattern. We noninvasively analyzed the effects on myocardial oxygen consumption (MVO2), perfusion (MBF) and pressure work efficiency by positron emission tomography (PET) before and after resynchronization therapy (CRT) in 31 patients with dilated cardiomyopathy (DCM) and LBBB. Methods 31 patients (19 males, 12 females) with DCM were studied at baseline and 3–4 months follow-up. Baseline characteristics: age 61±7 years; NYHA class 3.0±0.4, ejection fraction 22.1±7.1%, QRS duration 187±19 ms. MVO2 and MBF were measured from 11C-acetate kinetics with PET by a one-compartment model. MVO2 and MBF were normalized to rate pressure product (RPP) to account for different pressure loads and predicted energy demands. Results Global MVO2 assessed from 11C-acetate clearance did not change significantly between baseline and follow-up (0.080±0.015/min vs. 0.082±0.020/min). RPP-normalized MVO2 significantly decreased after CRT (0.072±0.018/min) vs. baseline (0.081±0.017/min; \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(P{

Resynchronization of segmental left ventricular mechanics as well as re-coordination of both atrio-ventricular and inter-ventricular contraction are potential mechanisms responsible for the clinical benefit observed in patients with advanced congestive heart failure treated by cardiac resynchronization therapy (CRT). Initially electrical conduction problems, in the majority of cases a left bundle branch block (LBBB), were considered the target for CRT. However, growing experience with CRT in different patient populations including those with only a mild degree of conduction disturbance, and improved cardiac imaging utilizing the tissue Doppler approach have shown the complexity of CRT and the usefulness of sophisticated echocardiographic imaging techniques for therapeutic decision making.

In patients with systolic heart failure the assessment of peak oxygen consumption during cardiopulmonary exercise (CPX) testing provides an objective measure of functional capacity and important prognostic information. Several studies in pacemaker therapy and in cardiac resynchronization therapy (CRT) have used peak oxygen uptake as an endpoint. This article reviews the impact of CPX testing on patient selection for CRT.

Hardware-related complications in implantable cardioverter/defibrillators (ICD) are still a common problem. Identifying underlying reasons becomes more and more difficult as the complexity of ICD systems increases. We report a patient with a dual chamber ICD (DDD-ICD) who suffered multiple complications. These included: ventricular oversensing causing inappropriate shocks and episodes of asystole; an insulation defect resulting in ineffective shocks as a consequence of a short circuit between the active can device and a defective high voltage cable; and device dysfunction requiring several hospitalizations and operative system revisions.