Background-Conventional activation mapping in the dilated human left ventricle (LV) with left bundle-branch block (LBBB) morphology is incomplete given the limited number of recording sites that may be collected in a reasonable time and given the lack of precision in marking specific anatomic locations. Methods and Results-We studied LV activation sequences in 24 patients with heart failure and LBBB QRS morphology with simultaneous application of 3D contact and noncontact mapping during intrinsic rhythm and asynchronous pacing. Approximately one third of the patients with typical LBBB QRS morphology had normal transseptal activation time and a slightly prolonged or near-normal LV endocardial activation time. A "U-shaped" activation wave front was present in 23 patients because of a line of block that was located anteriorly (nϭ12), laterally (nϭ8), and inferiorly (nϭ3).Patients with a lateral line of block had significantly shorter QRS (PϽ0.003) and transseptal durations (PϽ0.001) and a longer distance from the LV breakthrough site to line of block (PϽ0.03). Functional behavior of the line of block was demonstrated by a change in its location during asynchronous ventricular pacing at different sites and cycle lengths. Conclusions-A U-shaped conduction pattern is imposed on the LV activation sequence by a transmural functional line of block located between the LV septum and the lateral wall with a prolonged activation time. Assessment of functional block is facilitated by noncontact mapping, which may be useful for identifying and targeting specific locations that are optimal for successful cardiac resynchronization therapy.

An ACE-dependent increase in the amounts of activated Erk1/Erk2 in atrial interstitial cells may contribute as a molecular mechanism for the development of atrial fibrosis in patients with AF. These findings may have important impact on the treatment of AF.

AF is associated with the down-regulation of atrial AT(1)-R and the up-regulation of AT(2)-R proteins. These findings may help define the pathophysiological role of the angiotensin system in the structural remodeling of the fibrillating atria.

Transvenous catheter cryoablation is an effective method to create PV electrical isolation for the treatment of AF. A clinically satisfactory result can be achieved in 71% of patients with AF, without the risk of PV stenosis.

Atrial fibrillation (AF) is associated with impaired functional capacity and quality of life and significant morbidity and mortality. The current management approach fails to maintain stable sinus rhythm (SR) in the majority of patients. For many years, guidelines have recommended antiarrhythmic treatment of a first AF episode only if the AF is poorly tolerated, a position that has been reinforced by studies showing no mortality or morbidity advantage of rhythm control over rate control. During the last decade, research has shown mechanisms of self-perpetuation of AF based on electrophysiological and structural remodelling induced by AF itself. There is mounting evidence that 'lone' AF is because of a host of factors, some of which may be easily treatable, such as hypertension, sleep apnoea, and obesity, thus allowing secondary prevention at the time of the first episode of AF. According to these concepts, lack of early intervention could be one of the reasons for long-term failure of maintenance of SR. In this position paper, we propose testing the working hypothesis that if an SR maintenance strategy is selected, treatment of AF should commence at the first-detected episode and should be based on a double strategy of SR restoration and aggressive treatment of associated conditions that promote atrial remodelling.

Background-We tested the hypothesis that I Ca,L is important to the development of cardiac memory. Methods and Results-The effects of L-type Ca 2ϩ channel blockade and ␤-blockade were tested on acutely anesthetized and on chronically instrumented, conscious dogs. Short-term memory (STM) was induced by 2 hours of ventricular pacing and long-term memory (LTM) by ventricular pacing for 21 days. STM dogs received placebo, nifedipine, or propranolol, and LTM dogs received placebo, atenolol, or amlodipine. AT 1 receptor blockade (candesartan) and ACE inhibition (trandolapril) were also tested in LTM. Microelectrodes were used to record transmembrane potentials from isolated epicardial and endocardial slabs using a protocol simulating STM in intact animals. Left ventricular epicardial myocytes from LTM or sham control dogs were dissociated, and I Ca,L was recorded (whole-cell patch-clamp technique). Evolution of STM and LTM was attenuated by I Ca,L blockers but not ␤-blockers. Neither AT 1 receptor blockade nor ACE inhibition suppressed LTM. In microelectrode experiments, pacing induced an epicardial-endocardial gradient change mimicking STM that was suppressed by nifedipine. In patch-clamp experiments, peak I Ca,L density in LTM and control were equivalent, but activation was more positive and time constants of inactivation longer in LTM (PϽ0.05). Conclusions-I Ca,L blockade but not ␤-adrenergic blockade suppresses cardiac memory. LTM evolution is unaffected by angiotensin II blockade and is associated with altered I

This novel cryoablation system appears to be safe and can successfully treat different types of SVTs, including AF. Isolation of PVs is possible without producing stenosis. Despite the high blood flow in the right atrial isthmus and PVs, bidirectional conduction block can be achieved.

AimsThe rapidly increasing number of patients with implantable cardioverter-defibrillators (ICD) places a large burden on follow-up providers. This study investigated the possibility of longer in-office follow-up intervals in primary prevention ICD patients under remote monitoring with automatic daily data transmissions from the implant memory.Methods and resultsConducted in 155 ICD recipients with MADIT II indications, the study compared the burden of scheduled and unscheduled ICD follow-up visits, quality of life (SF-36), and clinical outcomes in patients randomized to either 3- or 12-month follow-up intervals in the period between 3 and 27 months after implantation. Remote monitoring (Biotronik Home Monitoring) was used equally in all patients. In contrast to previous clinical studies, no calendar-based remote data checks were performed between scheduled in-office visits. Compared with the 3-month follow-up interval, the 12-month interval resulted in a minor increase in the number of unscheduled follow-ups (0.64 vs. 0.27 per patient-year; P = 0.03) and in a major reduction in the total number of in-office ICD follow-ups (1.60 vs. 3.85 per patient-year; P < 0.001). No significant difference was found in mortality, hospitalization rate, or hospitalization length during the 2-year observation period, but more patients were lost to follow-up in the 12-month group (10 vs. 3; P = 0.04). The SF-36 scores favoured the 12-month intervals in the domains ‘social functioning’ and ‘mental health’.ConclusionIn prophylactic ICD recipients under automatic daily remote monitoring, the extension of the 3-month in-office follow-up interval to 12 months appeared to safely reduce the ICD follow-up burden during 27 months after implantation.ClinicalTrials.gov IdentifierNCT00401466 ().