Monitoring of atrial fibrillation burden after surgical ablation: relevancy of end-point criteria after radiofrequency ablation treatment of patients with lone atrial fibrillation.

Studies have shown that continuous rhythm monitoring enables the detection of significantly more atrial fibrillation (AF) episodes than routine follow-up of patients, i.e. based on perception of symptoms or on 24-48 h Holter monitoring. The positive outcome of radiofrequency ablation (RFA) may be easily overestimated, especially in patients with paroxysmal AF. Thirty-three consecutive patients, aged 59.4+/-8.9 years (range 38-75 years) participated in this study. All patients had documented AF episodes with an AF duration of 9.4+/-7.1 years (range 1.5-25 years). A new monitoring device, the AF-Alarm was used to more accurately assess the outcome after surgical isolation of pulmonary veins. The AF-Alarm was applied for a duration of 128+/-42.5 h (range 49-191 h) during a period of 8-15 days. The success rate was 87% based on serial electrocardiograms (ECGs) and 24-48 h Holter monitoring during regular outpatient visits. Combination of ECG, Holter and AF-Alarm data yielded a significantly lower success rate, i.e. at the latest follow-up 69% of the patients were free from AF after surgical ablation (P<0.05). Furthermore, the AF-Alarm device demonstrated a dissociation between symptoms and atrial arrhythmic events and confirmed the occurrence of asymptomatic AF episodes. The most important limitation of the AF-Alarm device was noise detection with oversensing and inappropriate detection of non-existing AF episodes in 9% of patients. Long-term follow-up of the patients seems to be essential as success rates of the initial ablation procedure might vary over time. External recorders like the AF-Alarm may be used as an additional tool to document symptomatic and asymptomatic episodes of atrial arrhythmias in the outpatient setting.

Randomized, double blind study of non-excitatory, cardiac contractility modulation electrical impulses for symptomatic heart failure.

AIMS: We performed a randomized, double blind, crossover study of cardiac contractility modulation (CCM) signals in heart failure patients. METHODS AND RESULTS: One hundred and sixty-four subjects with ejection fraction (EF) < 35% and NYHA Class II (24%) or III (76%) symptoms received a CCM pulse generator. Patients were randomly assigned to Group 1 (n = 80, CCM treatment 3 months, sham treatment second 3 months) or Group 2 (n = 84, sham treatment 3 months, CCM treatment second 3 months). The co-primary endpoints were changes in peak oxygen consumption (VO2,peak) and Minnesota Living with Heart Failure Questionnaire (MLWHFQ). Baseline EF (29.3 +/- 6.7% vs. 29.8 +/- 7.8%), VO2,peak (14.1 +/- 3.0 vs. 13.6 +/- 2.7 mL/kg/min), and MLWHFQ (38.9 +/- 27.4 vs. 36.5 +/- 27.1) were similar between the groups. VO2,peak increased similarly in both groups during the first 3 months (0.40 +/- 3.0 vs. 0.37 +/- 3.3 mL/kg/min, placebo effect). During the next 3 months, VO2,peak decreased in the group switched to sham (-0.86 +/- 3.06 mL/kg/min) and increased in patients switched to active treatment (0.16 +/- 2.50 mL/kg/min). MLWHFQ trended better with treatment (-12.06 +/- 15.33 vs. -9.70 +/- 16.71) during the first 3 months, increased during the second 3 months in the group switched to sham (+4.70 +/- 16.57), and decreased further in patients switched to active treatment (-0.70 +/- 15.13). A comparison of values at the end of active treatment periods vs. end of sham treatment periods indicates statistically significantly improved VO2,peak and MLWHFQ (P = 0.03 for each parameter). CONCLUSION: In patients with heart failure and left ventricular dysfunction, CCM signals appear safe; exercise tolerance and quality of life (MLWHFQ) were significantly better while patients were receiving active treatment with CCM for a 3-month period.

Clinical efficacy of cardiac resynchronization therapy using left ventricular pacing in heart failure patients stratified by severity of ventricular conduction delay.

OBJECTIVES: We assessed the clinical efficacy of single-site left ventricular (LV) pacing and determined the impact of baseline conduction delay severity on the magnitude of benefit. BACKGROUND: Multisite biventricular pacing can improve heart failure (HF) symptoms in patients with an intraventricular conduction delay by resynchronizing abnormal ventricular contractions and improving LV systolic function. METHODS: Eighty-six patients with at least New York Heart Association functional class II HF, chronic LV systolic dysfunction, normal sinus rhythm, and a QRS interval over 120 ms were implanted for atrial-synchronized LV pacing. The single-blinded, randomized, controlled, crossover study stratified patients 1:1 by the baseline QRS interval into long (QRS >150 ms) and short (QRS 120 to 150 ms) groups, which were compared during a three-month period of active (univentricular) pacing and a three-month period of inactive (ventricular inhibited) pacing. The primary end point was peak oxygen consumption (VO(2)) followed by anaerobic threshold, distance walked in 6 min, and quality-of-life questionnaire score. PATIENTS: Twelve patients were withdrawn before randomization and 17 could not complete both study periods. The short QRS group did not improve in any end point with active pacing. For the long QRS group, peak VO(2) increased 2.46 ml/min/kg (p < 0.001), the anaerobic threshold increased 1.55 ml/min/kg (p < 0.001), the distance walked in 6 min increased 47 m (p = 0.024), and the quality-of-life score improved 8.1 points (p = 0.004). CONCLUSIONS: Left ventricular pacing significantly improves exercise tolerance and quality of life in patients with chronic HF, LV systolic dysfunction, and a QRS interval over 150 ms.

Multisite atrial pacing for atrial fibrillation prevention: where to go from here?

Atrial fibrillation (AF) is a common arrhythmia associated with stroke, increased mortality and with a negative impact on quality of life. Pharmacologic treatments for AF have not provided long-term relief from arrhythmia recurrence. Multi-site atrial pacing was introduced by Daubert and colleagues about 10 years ago for the treatment of severe atrial conduction delays in patients with sick sinus syndrome. They found that this type of atrial stimulation reduced or prevented AF. Multi-site atrial pacing results in reduction of intra-atrial and interatrial conduction differences and diminishes heterogeneity of refractoriness, i.e. atrial resynchronization. Acute electrophysiological studies have shown that biatrial stimulation reduced AF inducibility. The Dutch Dual-site Right Atrial Pacing for Prevention of Atrial Fibrillation study was a prospective randomized crossover trial comparing the recurrences of AF in dual-site right atrial and single-site high right atrial pacing in patients with symptomatic medically refractory AF, without or with minimal structural heart disease. Patients were randomized to initial dual-site pacing (Group I n = 18) or initial single-site (Group II n = 22) pacing. After 6 months or after a study endpoint was reached patients were crossed over to the other pacing modality.Although, the arrhythmia free intervals were longer for dual-site pacing during both treatments periods (Group I 162 +/- 12 and Group II 114 +/- 15 days) compared to single-site pacing (Group I 143 +/- 16 and Group II 97 +/- 10 days) the difference was not statistically significant (p = 0.061). However, the sequence of the randomized treatment periods had a significant effect on outcome (p < 0.02). Event free intervals (AF > 48 hours requiring electrical cardioversion) were longer during dual-site pacing in both groups compared to single-site stimulation but the difference was statistically not significant (p = 0.055) because of treatment interaction (P < 0.05). To establish the clinical benefits of multi-site pacing for the treatment of patients with medically refractory symptomatic AF, additional prospective randomized studies are needed. Trials with a parallel design are necessary to avoid carry-over effects of different stimulation protocols.