Clinical and anatomic predictors of need for repeat atrial fibrillation ablation.

AIM: To identify predictors of need for repeat procedures after initial atrial fibrillation (AF) ablation. METHODS: We identified a cohort undergoing first time AF ablation at our institution from January 2004 to February 2014 who had cardiac magnetic resonance (CMR) imaging performed prior to ablation. Clinical variables and anatomic characteristics (determined from CMR) were assessed as predictors of need for repeat ablation. The decision regarding need for and timing of repeat ablation was at the discretion of the treating physician. RESULTS: From a cohort of 331 patients, 142 patients (43%) underwent repeat ablation at a mean of 13.6 ± 18.4 mo after the index procedure. Both male gender (81% vs 71%, P = 0.05) and lower ejection fraction (57.4% ± 10.3% vs 59.8% ± 9.4%, P = 0.04) were associated with need for repeat ablation. On pre-ablation CMR, mean pulmonary vein (PV) diameters were significantly larger in all four PVs among patients requiring repeat procedures. In multivariate analysis, increased right superior PV diameter significantly predicted need for repeat ablation (odds ratio 1.08 per millimeter increase in diameter, 95%CI: 1.00-1.16, P = 0.05). There were also trends toward significance for increased left and right inferior PV sizes among those requiring repeat procedures. CONCLUSION: Increased PV size predicts the need for repeat AF ablation, with each millimeter increase in PV diameter associated with an approximately 5%-10% increased risk of requiring repeat procedures.

Pulmonary Vein Remodeling Following Atrial Fibrillation Ablation: Implications For The Radiographic Diagnosis Of Pulmonary Vein Stenosis.

Background: Pulmonary vein (PV) reverse remodeling has been recognized following atrial fibrillation (AF) ablation. However, the extent of physiologic reverse remodeling after AF ablation and the potential impact of reverse remodeling on the radiographic diagnosis of PV stenosis have not been well characterized. Methods: From January 2004 to February 2014, 186 patients underwent paired cardiac magnetic resonance imaging (MRI) to delineate PV orifice dimensions before and after (mean 109 ± 61 days) an initial AF ablation. Results: Negative remodeling of the PV orifice cross sectional area occurred in 67.8% of veins with a mean reduction in area of 21.0 ± 14.1%, and positive remodeling was seen in the remaining PVs with an increase in area of 22.1 ± 23.4% compared to baseline. No PVs demonstrated a reduction in cross-sectional area of > 75% (maximum reduction observed was 58%). Negative remodeling of the PV long axis dimension was observed in 55.2% of veins with a mean reduction of 14.6 ± 9.2% compared to pre-ablation and positive remodeling was observed in 25.3% of PVs with a mean increase in diameter of 14.7 ± 12.6%. Only 1 PV demonstrated a reduction in orifice diameter of > 50%. There were no clinically evident or suspected cases of PV stenosis in this cohort. Conclusions: Negative remodeling of the PV orifice area was noted in the majority of PVs following AF ablation. However, in almost all cases, the extent of negative remodeling was well below commonly used thresholds for the radiographic diagnosis of PV stenosis.

Pulmonary vein anatomy assessed by cardiac magnetic resonance imaging in patients undergoing initial atrial fibrillation ablation: implications for novel ablation technologies.

BACKGROUND: Novel atrial fibrillation (AF) ablation tools have been designed to facilitate "single-shot" pulmonary vein (PV) isolation using multi-electrode or balloon-based catheters. However, in contrast to point-by-point radiofrequency ablation, these tools may be more dependent on suitable PV anatomy to achieve circumferential PV isolation. METHODS: Three hundred and twenty-two patients underwent gadolinium-enhanced cardiac magnetic resonance angiography to delineate PV anatomy prior to initial AF ablation. Long (a) and short (b) axis measurements of the PV orifice were used to calculate the eccentricity index of the PV ostium. RESULTS: Long axis dimensions of the left superior PV were 18.2 ± 3.3 mm, left inferior PV 17.7 ± 3.9 mm, right superior PV (RSPV) 20.4 ± 4.3, and right inferior PV 18.7 ± 4.7 mm. The long axis dimension of the RSPV was significantly larger than other PVs (p < 0.001). Forty-two patients (13 %) had at least one PV with a long axis dimension >25 mm and 16 patients (5 %) had at least one PV with a long axis dimension >28 mm. Left-sided PV ostia were significantly more ellipse-shaped than the right-sided PVs, which tended to be more spherical. A significant positive correlation was noted between increasing PV size and increased orifice eccentricity. CONCLUSIONS: In this large cohort undergoing initial AF ablation, over 10 % of patients had at least one standard PV with a dimension >25 mm. Additionally, significant differences were noted between left- and right-sided veins with regard to orifice eccentricity. These findings have implications for the design of AF ablation tools and may account for differential isolation rates between PVs noted in some recent studies of novel ablation technologies.

Dynamic seeding of perfusing human umbilical vein endothelial cells (HUVECs) onto dual-function cell adhesion ligands: Arg-Gly-Asp (RGD)-streptavidin and biotinylated fibronectin.

Surfaces decorated with high affinity ligands can be used to facilitate rapid attachment of endothelial cells; however, standard equilibrium cell detachment studies are poorly suited for assessing these initial adhesion events. Here, a dynamic seeding and cell retention method was used to examine the initial attachment of perfusing human umbilical vein endothelial cells (HUVECs) to bare Teflon-AF substrates, substrates pre-adsorbed with fibronectin alone, or substrates co-pre-adsorbed with two dual-function cell-adhesion ligands: biotinylated fibronectin (bFN) and RGD-streptavidin mutant (RGD-SA). Cell attachment was evaluated as a function of cell trypsinization (integrin digestion), surface protein formulation, and cell perfusion rate. Surfaces co-pre-adsorbed with bFN and RGD-SA showed the highest density of attached cells after 8 min of perfusion and the highest percent retention when subjected to shear flow at 60 dynes/cm2 for 2 min. Surfaces with no ligand treatment showed the lowest cell attachment and retention under flow in all cases. HUVECs trypsinized with mild 0.025% trypsin/ethylenediaminetetraacetic acid (EDTA) showed greater cell adhesion after perfusion and higher percent retention after shear flow than those trypsinized using harsher 0.05% trypsin/EDTA. The preferential affinities of the two dual-function ligands for alpha5beta1 and alphavbeta3 integrins were also examined by surface plasmon resonance (SPR) spectroscopy. The dynamic cell seeding studies confirmed that the dual-function ligand system promotes HUVEC adhesion and retention at short time points when tested using a perfusion assay. SPR studies showed that the two ligands exhibited equal affinity for both alpha5beta1 and alphavbeta3 integrins but that the combined ligands bound more total integrins than the two ligands tested separately.