The risk of atrial fibrillation during right ventricular pacing.

AIMS: Right ventricular pacing adversely affects left atrial (LA) structure and function that may trigger atrial fibrillation (AF). This study compares the occurrence of persistent/permanent AF during long-term Hisian area (HA), right ventricular septal (RVS), and right ventricular apex (RVA) pacing in patients with complete/advanced atrioventricular block (AVB). METHODS AND RESULTS: We collected retrospective data from 477 consecutive patients who underwent pacemaker implantation for complete/advanced AVB. Ventricular pacing leads were located in the HA, RVS, and RVA in 148, 140, and 189 patients, respectively. The occurrence of persistent/permanent AF was observed in 114 (23.9%) patients (follow-up 58.5 ± 26.5 months). Hisian area groups presented a lower rate of AF occurrence (16.9%) compared with RVS and RVA groups (25.7 and 28.0%, respectively), P = 0.049. Cox's proportional hazard model was used to estimate HR. The risk of persistent/permanent AF was significantly lower in the patients paced from HA compared with those paced from RVA, HR = 0.28 (95% CI 0.16-0.48, P = 0.0001). The RVS and RVA pacing groups showed a similar AF risk: HR 1.04 (95% CI 0.66-1.64, P = 0.856). Other independent predictors of persistent/permanent AF occurrence included previous (before device implantation) paroxysmal AF (HR = 4.08; 95% CI 3.15-7.31, P = 0.0001), LA diameter, and age, whereas baseline bundle-branch block was associated with a lower risk of AF occurrence (HR = 0.56; 95% CI 0.35-0.81, P = 0.003). CONCLUSIONS: HA pacing compared with RVA or RVS pacing seems to be associated with a lower risk of persistent/permanent AF occurrence. The risk of persistent/permanent AF was similar in the RVA vs. RVS groups.

Efficacy of low interatrial septum and right atrial appendage pacing for prevention of permanent atrial fibrillation in patients with sinus node disease: results from the electrophysiology-guided pacing site selection (EPASS) study.

BACKGROUND: The role of pacing sites and atrial electrophysiology on the progression of atrial fibrillation (AF) to the permanent form in patients with sinus node dysfunction (SND) has never been investigated. The aim of the study was to investigate the relationship between atrial electrophysiology and the efficacy of atrial pacing at the low interatrial septum (IAS) or at the right atrial appendage (RAA) to prevent persistent/permanent AF in patients with SND. METHODS AND RESULTS: The Electrophysiology-Guided Pacing Site Selection (EPASS) Study was a prospective, controlled, randomized study. Atrial refractoriness, basal and incremental conduction times from the RAA to the coronary sinus ostium were measured before implantation, and the difference (ΔCTos) was calculated. Patients with ΔCTos ≥ 50 ms (study group) and those with ΔCTos <50 ms (control group) were randomly assigned to RAA or IAS with algorithms for continuous atrial stimulation "on." The primary end point was time to development of permanent or persistent AF within a 2-year follow-up in the study group, IAS versus RAA. Data were analyzed by intention to treat. One hundred two patients (77 ± 7 years, 44 mol/L) were enrolled, 69 (68%) in the study group and 33 (32%) in the control group. Of these, 97 ended the study, respectively, randomly assigned: 29 IAS versus 36 RAA and 18 IAS versus 14 RAA. After a mean follow-up of 15 ± 7 (median, 17) months, 11 (16.6%) patients in the study group met the primary end point: 2 IAS versus 9 RAA (log rank=3.93, P=0.047). CONCLUSIONS: In patients with SND and intra-atrial conduction delay, low IAS pacing was superior to RAA pacing in preventing progression to persistent or permanent AF. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00239226.

Cardiac resynchronization therapy and bone marrow cell transplantation in patients with ischemic heart failure and electromechanical dyssynchrony: a randomized pilot study.

Most studies have confirmed the beneficial effects of autologous bone marrow mononuclear cell (BMMC) transplantation on angina, myocardial perfusion, regional wall motion, and LV ejection fraction (LVEF). Cardiac resynchronization therapy (CRT) has also shown a beneficial effect in patients with heart failure (HF) and electrical/mechanical dyssynchrony. However, the relative contribution of BMMC and CRT in patients with ischemic HF and electromechanical dyssynchrony has never been investigated. The aim of this study was to evaluate the benefit of combining BMMC transplantation with CRT in patients with severe ischemic HF, left bundle branch block (LBBB), and mechanical dyssynchrony. Patients with ischemic HF, LVEF < 35%, LBBB, and mechanical dyssynchrony underwent intramyocardial transplantation of BMMC and CRTD system implantation. This randomized, single-blind, crossover study compared clinical and echocardiographic parameters during two follow-up periods: 6 months of active CRT (BMMC + CRTact) and 6 months of inactive CRT (BMMC + CRTinact). Physical performance was assessed by means of a 6-min walking test. Myocardial perfusion was evaluated by SPECT. Quality of Life (QoL) was assessed through the Minnesota Living with HF Questionnaire (MLwHFQ). Twenty-six patients (64 ± 7 years) were enrolled in the study. The distance covered by the patients during the 6-min walking test significantly increased in the BMMC + CRTinact phase (BMMC therapy only) in comparison with the baseline (269 ± 68 vs 206 ± 51; p = 0.007) and in the BMMC + CRTact phase (BMMC therapy + CRT) in comparison with the BMMC + CRTinact (378 ± 59 vs 269 ± 68; p < 0.001). The summed rest and stress score (SPECT) decreased significantly in the BMMC + CRTact and BMMC + CRTinact phases in comparison with the baseline (p ≤ 0.03). Both phases showed equivalent myocardial perfusion in the segments into which BMMC had been injected. QoL score was significantly lower in the BMMC + CRTinact phase than at the baseline (44.1 ± 14 vs 64.8 ± 19; p < 0.001), and in the BMMC + CRTact phase than in the BMMC + CRTinact phase (26.4 ± 12 vs 44.1 ± 14; p = 0.004). BMMC and CRT seem to act independently on myocardial perfusion and electromechanical dyssynchrony, respectively. Combining these two complementary therapies can significantly improve LV performance in patients with severe HF and electromechanical dyssynchrony.

Methods for testing automatic mode switching in patients implanted with DDD(R) pacemakers.

The assessment of automatic mode switching (AMS) algorithms is impossible in vivo, due to a low chance of seeing the patient at the onset of a spontaneous episode of atrial fibrillation (AF). As the induction of AF to test AMS has clinical concerns, three alternative and non-invasive techniques may be proposed for this purpose: myopotentials, chest wall stimulation, and an external supraventricular arrhythmia simulator. The first method is simple and does not require additional equipment, even though in some patients adequate signals cannot be generated with a soft effort such as handgrip or hand compression. The main advantage of the chest wall stimulation method is the possibility that it be performed in every implanting center, since it is based on the use of standard devices for cardiac stimulation. The method based on the external supraventricular arrhythmia simulator allows the most detailed of the ECG traces, but it needs a dedicated electronic device.