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Aims To evaluate the incidence and clinical significance of diaphragmatic myopotential (dMP) oversensing in pacemaker (PM)-dependent patients with CRT-Ds. Methods and results We retrospectively evaluated patients with CRT-Ds implanted at our institution between January 2000 and August 2006. PM-dependent patients were identified, and the incidence of inappropriate detections due to dMP oversensing and their possible clinical implications (inappropriate therapies, syncope, and death of any cause) were evaluated. CRT-Ds were implanted in 122 patients, 37 were or became PM dependent. During a mean follow-up of 22+ 17 months, 7(18.9%) PM-dependent patients revealed inappropriate detections due to dMP oversensing. All oversensing episodes occurred in CRT-Ds with automatic gain control (AGC) sensing and integrated bipolar (IBP) leads in the RV apex. These detections led to inappropriate shocks in 2(5.4%) patients and syncope in 1(2.7%). Five (13.5%) patients died. Conclusion dMP oversensing in PM-dependent patients with CRT-Ds is an important problem, particularly in CRT-Ds with AGC sensing and IBP leads, with over 20% of patients with these devices revealing inappropriate detections. The clinical impact of dMP oversensing is less marked but relevant, with both inappropriate therapies and syncope occurring in this small group of 37 patients and the possibility of related deaths.

Aims To evaluate the usefulness of three-dimensional (3D) electroanatomical mapping of the pulmonary veins (PV) for guiding radiofrequency (RF) ablation of focal atrial fibrillation (AF) in a single session and to correlate the electrophysiological results with the six month clinical outcome. Methods and Results Sixteen consecutive patients with idiopathic paroxysmal AF (more than 1 episode/month) were studied. A non-fluoroscopic mapping system was used to generate 3D electroanatomic maps of the left atrium and deliver RF energy. In patients with frequent ectopies, mapping was performed using the ‘hot-cold’ approach (looking for the earliest electrogram in the 3D reconstruction). In patients with infrequent/no ectopies, double/multiple potentials recorded at the PV were tagged. Pacing at these sites to test for inducibility of ectopy or atrial fibrillation was used to define PV foci. The therapeutic endpoint was defined as suppression of premature beats, dissociation of PV potentials and inability to induce AF. Twenty-five foci were identified (multiple foci in 38%). In the 4 pts with frequent ectopies, Group A, these were suppressed by 4±4·7 applications. In the 12 pts with infrequent/no ectopies, Group B, an average 4·7±1·8 applications were delivered per focus; the endpoint was achieved in eight of the patients (13 of 21 foci). By 180 days follow-up, 11 patients were free of symptoms and in sinus rhythm, two had paroxysmal AF episodes and 3 have symptomatic ectopies and are receiving antiarrhythmic drugs. The overall success rate at six months was thus 69%, 100% for group A and 58% for group B. Conclusion Electroanatomic guided RF ablation of paroxysmal AF was highly successful in patients with frequent ectopies. The use of electroanatomical mapping for precise anatomical localization of multiple potentials and for guiding the PV ostia isolation allowed successful RF ablation in 50% of pts with infrequent/no ectopies.

In the letter, Doctors Lam and Owen offer some very relevant comments on the recommendations for cardiac resynchronization combined with defibrillation therapy (CRT-D) in the ESC guidelines.1 In regard to point 3.2.1, the authors provide further evidence from a network meta-analysis2 grouping randomized controlled trials …