Subclinical atrial fibrillation detection with a floating atrial sensing dipole in single lead implantable cardioverter-defibrillator systems: Results of the SENSE trial.

INTRODUCTION: Subclinical atrial fibrillation (AF), in the form of cardiac implantable device-detected atrial high rate episodes (AHREs), has been associated with increased thromboembolism. An implantable cardioverter-defibrillator (ICD) lead with a floating atrial dipole may permit a single lead (DX) ICD system to detect AHREs. We sought to assess the utility of the DX ICD system for subclinical AF detection in patients, with a prospective multicenter, cohort-controlled trial. METHODS AND RESULTS: One hundred fifty patients without prior history of AF (age 59 ± 13 years; 108 [72%] male) were enrolled into the DX cohort and implanted with a Biotronik DX ICD system at eight centers. Age-, sex-, and left ventricular ejection fraction-matched single- and dual-chamber ICD cohorts were derived from a Cornell database and from the IMPACT trial, respectively. The primary endpoint were AHRE detection at 12 months. During median 12 months follow-up, AHREs were detected in 19 (13%) patients in the DX, 8 (5.3%) in the single-chamber, and 19 (13%) in the dual-chamber cohorts. The rate of AHRE detection was significantly higher in the DX cohort compared to the single-chamber cohort (P = .026), but not significantly different compared to the dual-chamber cohort. There were no inappropriate ICD therapies in the DX cohort. At 12 months, only 3.0% of patients in the DX cohort had sensed atrial amplitudes less than 1.0 mV. CONCLUSION: Use of a DX ICD lead allows subclinical AF detection with a single lead DX system that is superior to that of a conventional single-chamber ICD system.

Incidence and predictors of very late recurrence of atrial fibrillation after ablation.

INTRODUCTION: Radiofrequency catheter ablation can effectively treat patients with refractory atrial fibrillation (AF). Very late AF recurrence (> or = 12 months post-ablation) is uncommon and may represent a unique patient cohort. METHODS AND RESULTS: A nested case-control study was performed in the cohort who underwent AF ablation at the University of Pennsylvania to characterize patients who develop very late AF recurrence after ablation. The procedure consisted of isolation of pulmonary veins (PVs) demonstrating triggers and elimination of non-PV triggers initiating AF. Twenty-seven (7.9%) patients with very late recurrence were compared to 219 patients without recurrence and > or = 12 months of follow-up. The mean age was 54.6 +/- 11.3 years and 79% were men. Very late recurrence patients more likely weighed >200 lbs (70% vs 55%, P = 0.01); during initial ablation had fewer PVs isolated (2.8 +/- 1.1 vs 3.3 +/- 1.0, P = 0.03); and were less likely to have right inferior PV isolation (37% vs 61%, P = 0.02), less likely to have isolation of all PVs (30% vs 56%, P = 0.01), and more likely to have non-PV triggers (30% vs 11% OR 3.4(95% CI, 1.3-8.7), P = 0.01). PV reconnectivity and new triggers were found in the majority of patients with very late recurrence of AF who underwent repeat ablation. CONCLUSION: Very late recurrence of AF more likely occurred in patients >200 lbs who demonstrated non-PV triggers and did not undergo right inferior PV isolation. The majority of patients undergoing repeat ablation for very late recurrence demonstrated PV reconnectivity and new non-PV and PV triggers not observed during the initial ablation.