Ischaemic stroke prevention in patients with atrial fibrillation and high bleeding risk: opportunities and challenges for percutaneous left atrial appendage occlusion.

Patients with atrial fibrillation (AF) are at an increased risk of ischaemic stroke. The efficacy of stroke prevention with vitamin K antagonists in these patients has been well established. However, associated bleeding risks may offset the therapeutic benefits in patients with risk factors for bleeding. Despite improvements achieved by novel oral anticoagulants, bleeding remains a clinically relevant problem, especially gastrointestinal bleeding. Percutaneous occlusion of the left atrial appendage (LAA) may be considered as an alternative stroke prevention therapy in AF patients with a high bleeding risk. This paper explores patient groups in whom oral anticoagulation may be challenging and percutaneous LAA occlusion (LAAO) has a potentially better risk-benefit balance. The current status of LAAO and future directions are reviewed, and particular challenges for LAA occlusion requiring further clinical data are discussed. This article is a summary of the Third Global Summit on LAA occlusion, 15 March 2013, Barcelona, Spain.

Conventional and dedicated atrial overdrive pacing for the prevention of paroxysmal atrial fibrillation: the AFTherapy study.

AIMS: This investigation was conducted to determine the effectiveness of several conventional overdrive pacing modalities (single rate and rate responsive pacing at various lower rates) and of four dedicated preventive pacing algorithms in the suppression of paroxysmal atrial fibrillation (AF). METHOD AND RESULTS: In this multi-centre, randomized trial, 372 patients with drug-refractory paroxysmal AF were enrolled. Patients received a dual-chamber pacing device capable of delivering conventional pacing therapy as well as dedicated AF prevention pacing therapies and to record detailed AF-related diagnostics. The primary endpoint was AF burden, whereas secondary endpoints were time to first AF episode and averaged sinus rhythm duration. During a conventional pacing phase, patients were randomized to single rate or rate-responsive pacing with lower rates of either 70 or 85 min(-1) or to a control group with single rate pacing at 40 min(-1). In the subsequent preventive pacing phase, patients underwent pacing at a lower rate of 70 min(-1) with or without concomitant application of four preventive pacing algorithms. A substantial amount of data was excluded from the analysis because of atrial-sensing artefacts, identified in the device-captured diagnostics. In the conventional pacing phase, no significant differences were found between various lower rates and the control group receiving single rate pacing at 40 min(-1) or between single rate and rate-responsive pacing. Patients receiving preventive pacing with all four therapies enabled had a similar AF burden compared with patients treated with conventional pacing at 70 min(-1) (P = 0.47). CONCLUSIONS: The results do not demonstrate a significant effect of conventional atrial overdrive pacing or preventive pacing therapies. However, the observations provided important information for further consideration with respect to the design and conduct of future studies on the effect of atrial pacing therapies for the reduction of AF.

[Cost effectiveness of preventive antibiotic administration for lowering risk of infection by 0.25%]. / Kosteneffektivität einer Antibiotikaprophylaxe bei Senkung des Infektionsrisikos um 0.25%.

Antibiotic prophylaxis in closed fractures is cost-effective if the risk of a deep infection is reduced by 0.25%. This control study was undertaken to assess the cost-effectiveness of prophylaxis of postoperative infections after surgical treatment of closed fractures. The costs for 16 patients with infections (8 with deep infections, 8 with superficial infections) were investigated and compared with the costs for 16 similar but non-infected patients with special reference to length of hospital stay, antibiotics and surgery. The data were collected from the trauma department of the University Hospital of the Free University in Amsterdam. Costs in the group of 8 patients with superficial wound infection were not substantially higher than those for their non-infected controls. The occurrence of a deep infection meant costs an average of DFL 35,224 higher than an uneventful postoperative course. On the basis of these results, antibiotic prophylaxis of postoperative wound infections is cost-effective if it reduces the risk of deep wound infections by about 0.25%.

Avoiding atrial undersensing by assessment of P wave amplitude histogram data.

Reliable sensing of the P wave is an essential requirement for the appropriate functioning of any device that uses atrial tracking to provide AV synchrony. However, a single measurement of the P wave amplitude, either at implantation or during follow-up, may not be a reliable reflection of the P wave amplitudes that occur during daily life. The P wave amplitude histogram is a new feature that automatically measures the P wave amplitude at regular intervals and provides the distribution of these measurements. This enables the assessment of the smallest P wave amplitudes that occur. Two populations were studied: 104 patients with a fixed atrial lead and a DDDR pacemaker and 100 patients with a single pass VDD lead and a VDD pacemaker. Both pacemakers incorporate the P wave amplitude histogram feature. Data in the P wave amplitude histogram were compared with a single measurement of the P wave amplitude at each follow-up. Programming of a 100% safety margin based on a single measurement of the P wave amplitude provided reliable atrial sensing in only 72% and 43% of the patients of both populations, respectively. Data continued in the P wave amplitude histogram may be a useful adjunct for the optimal programming of atrial sensitivity.

[Antibiotic prophylaxis in closed fractures is cost-effective if the possibility of a deep infection decreases through this by 0.25%]. / Antibiotische profylaxe bij gesloten fracturen kosten-effectief als de kans op een diepe infectie erdoor afneemt met 0.25%.

This patient-control study was undertaken to assess the cost-effectiveness of prophylaxis of postoperative infections after surgical treatment of closed fractures. The costs of 16 patients with an infection (8 with deep infections, 8 with superficial infections) were investigated and compared with the costs of 16 similar noninfected patients for the parameters hospital stay, antibiotics and surgery. The data were collected from the trauma department of the University Hospital of the Free University of Amsterdam. There were no substantial extra costs in the group of the 8 patients with superficial wound infection compared with their noninfected controls. The mean extra costs for a deep infection in the other 8 patients were Dfl 35,224.-. Considering these results, antibiotic prophylaxis of postoperative wound infections is cost-effective, if it leads to a decrease of the risk of deep wound infections by about 0.25%.

Quantitative analysis of single muscle fibre action potentials recorded at known distances.

In vivo records of single fibre action potentials (SFAPs) have always been obtained at unknown distance from the active muscle fibre. A new experimental method has been developed enabling the derivation of the recording distance in animal experiments. A single fibre is stimulated with an intracellular micropipette electrode. The same electrode is used thereafter for labelling with an auto-fluorescent dye, Lucifer Yellow. In this method there is no use of chemical fixation. The tissue structure is kept as well as possible. In cross-sections the fluorescent fibre is seen and its position is quantitized with respect to the tip of one or more recording wire electrodes. Morphometric data, such as the recording distance and the fibre cross-sectional area, are used for the interpretation of parameters of the SFAPs (peak-peak amplitude, time between the first positive and negative peaks). The present results show that within 300 microns recording distance is not as dominant for the SFAP shape as expected. The method offers also a direct check of the relation between the muscle fibre; diameter and the conduction velocity of the action potential. In the present small set of data there is no simple linear relationship.