Right ventricular stimulation threshold at ICD implant predicts device therapy in primary prevention patients with ischaemic heart disease.

AIMS: Myocardial excitability is known (amongst other reasons) to be related to the degree of ischaemia, contractile dysfunction and heart failure. It was hypothesized that the right ventricular (RV) stimulation threshold has prognostic value with respect to the occurrence of ventricular arrhythmias (VAs) and patient survival in recipients of an implantable cardioverter defibrillator (ICD). METHODS AND RESULTS: Ischaemic heart disease patients receiving an ICD at Leiden University Medical Center as primary prevention for sudden cardiac death were included in this study. Right ventricular thresholds were determined at ICD implant. Data were collected on VAs triggering ICD therapy and on all-cause mortality. A total of 689 consecutive patients were included (87% male, age 63 ± 11 years, left ventricular ejection fraction (LVEF) 29 ± 11%) and followed for a median of 28 months. Post-implant RV-threshold was 0.7 ± 0.5 volt (V) at 0.5 ms pulse duration. Best dichotomous separation was reached at a cut-off of 1 V. During follow-up, 167 (24%) patients received appropriate ICD therapy, 88 (13%) had appropriate shocks and 134 (19%) died. Cumulative appropriate shock incidence for patients with RV threshold ≥ 1 V (n = 166) was 16% at 1 year, 24% at 3 years and 34% at 5 years compared with 4, 11 and 17% for patients with an RV-threshold < 1 V (n = 523). Adjusted hazard ratio of RV threshold ≥ 1 V was 2.0 (95% CI: 1.4-2.9) for appropriate therapy, 3.3 (95% CI: 2.0-5.4) for appropriate shocks and 1.6 (95% CI: 1.1-2.5) for mortality. CONCLUSION: The RV stimulation threshold at ICD implant has a strong independent prognostic value for the occurrence of VAs triggering appropriate ICD therapy, appropriate shocks and mortality.

Left atrial strain predicts reverse remodeling after catheter ablation for atrial fibrillation.

OBJECTIVES: The purpose of this study was to assess left atrial (LA) strain during long-term follow-up after catheter ablation for atrial fibrillation and to find predictors for LA reverse remodeling. BACKGROUND: The association between LA reverse remodeling and improvement in LA strain after catheter ablation has not been investigated thus far. METHODS: In 148 patients undergoing catheter ablation for atrial fibrillation, LA volumes and LA strain were assessed with echocardiography at baseline and after a mean of 13.2 ± 6.7 months of follow-up. The study population was divided according to LA reverse remodeling at follow-up: responders were defined as patients who exhibited 15% or more reduction in maximum LA volume at long-term follow-up. Left atrial systolic (LAs) strain was assessed with tissue Doppler imaging. RESULTS: At follow-up, 93 patients (63%) were classified as responders, whereas 55 patients (37%) were nonresponders. At baseline, LAs strain was significantly higher in the responders as compared with the nonresponders (19 ± 8% vs. 14 ± 6%; p = 0.001). Among the responders, a significant increase in LAs strain was noted from baseline to follow-up (from 19 ± 8% to 22 ± 9%; p < 0.05), whereas no change was noted among the nonresponders. LAs strain at baseline was an independent predictor of LA reverse remodeling (odds ratio: 1.813; 95% confidence interval: 1.102 to 2.982; p = 0.019). CONCLUSIONS: In the present study, 63% of the patients exhibited LA reverse remodeling after catheter ablation for atrial fibrillation, with a concomitant improvement in LA strain. LA strain at baseline was an independent predictor of LA reverse remodeling.

Real-time integration of intracardiac echocardiography and multislice computed tomography to guide radiofrequency catheter ablation for atrial fibrillation.

BACKGROUND: Multislice computed tomography (MSCT) integration is commonly used to guide radiofrequency catheter ablation (RFCA) for atrial fibrillation (AF). MSCT provides detailed anatomical information but lacks the ability to provide real-time anatomy during RFCA. Intracardiac echocardiography (ICE) allows real-time visualization of cardiac structures. OBJECTIVE: The purpose of this study was to investigate the feasibility of three-dimensional (3D) anatomical mapping of the left atrium (LA) with ICE and integrating the 3D map with MSCT to facilitate RFCA for AF. METHODS: In 17 patients undergoing RFCA for AF, 3D mapping of the LA was performed with ICE using a new mapping system that allows tracking of a new ICE probe. On each ICE image, endocardial contours were traced and used to generate a 3D map of the LA and pulmonary veins (PVs). A preprocedurally acquired MSCT image of the LA was then integrated with the 3D map. Additionally, PV assessment with ICE was compared with MSCT. RESULTS: Accurate 3D mapping could be performed in all patients with a mean number of 31.1 +/- 8.5 contours. Integration with MSCT resulted in a mean distance between the MSCT and ICE contours of 2.2 +/- 0.3 mm for the LA and PVs together and of 1.7 +/- 0.2 mm around the PV ostia specifically. Agreement in the assessment of PV anatomy and diameters between ICE and MSCT was excellent. CONCLUSION: Three-dimensional ICE mapping of the LA is feasible. The 3D map created with ICE can be merged with MSCT to facilitate RFCA for AF.

Calcium sensitizer EMD 57033, but not the beta1-adrenoreceptor agonist dobutamine, increases mechanical efficiency in stunned myocardium.

External work, efficiency of energy transfer (EET), and mechanical efficiency (defined as the ratio of external work over myocardial oxygen consumption (MVO2) are reduced in stunned myocardium. We therefore evaluated how inotropic stimulation by dobutamine and the calcium sensitizer EMD 57033 affected the regional stress-strain relationship as, from which contractility (E(es)), external work at the working point (EWwp), maximal external work (EWmax), EETwp (%), and EETmax are determined. Thirty minutes after regional stunning in 11 open chest pigs by two 10-min coronary occlusions separated by 10 min of reperfusion, dobutamine (0.5, 1, and 2 microg x kg(-1) x min(-1)) was infused, after an ample washout period followed by infusion of EMD 57033 (0.05, 0.1, 0.2 mg x kg(-1) x min(-1)). Stunning decreased E(es) (30%), EWwp (56%), EWmax (63%), EETwp (34%), EETmax (33%) and mechanical efficiency (55%), but MVO2 was unaffected. EWwp, EWmax, EETwp, and EETmax increased similarly with the two drugs, whereas MVO2 increased only after dobutamine. Consequently, mechanical efficiency increased linearly with contractility during EMD 57033 infusion but remained constant during infusion of dobutamine.