No abstract

Background Atrial fibrillation (AF) is associated with left atrial (LA) structural and functional changes. Cardiac magnetic resonance (CMR) late gadolinium enhancement (LGE) and feature-tracking are capable of noninvasive quantification of LA fibrosis and myocardial motion, respectively. We sought to examine the association of phasic LA function with LA enhancement in patients with AF. Methods and Results LA structure and function was measured in 90 AF patients (age 61 ± 10 years, 76% male) referred for ablation and 14 healthy volunteers. Peak global longitudinal LA strain (PLAS), LA systolic strain rate (SR-s), and early (SR-ed) and late diastolic (SR-ld) strain rates were measured using cine-CMR images acquired during sinus rhythm. The degree of LGE was quantified. Compared to patients with paroxysmal AF (60% of cohort), those with persistent AF had larger maximum LA volume index (LAVImax, 56 ± 17ml/m2 versus 49 ± 13ml/m2 p=0.036), and increased LGE (27.1± 11.7% versus 36.8 ± 14.8% p<0.001). Aside from LA active emptying fraction, all LA parameters (passive emptying fraction, PLAS, SR-s, SR-ed and SR-ld) were lower in patients with persistent AF (p< 0.05 for all). Healthy volunteers had less LGE and higher LA functional parameters compared to AF patients (p<0.05 for all). In multivariable analysis, increased LGE was associated with lower LA passive emptying fraction, PLAS, SR-s, SR-ed, and SR-ld (p<0.05 for all). Conclusions Increased LA enhancement is associated with decreased LA reservoir, conduit, and booster pump functions. Phasic measurement of LA function using feature-tracking CMR may add important information regarding the physiological importance of LA fibrosis.

Background Pulmonary vein isolation (PVI) for atrial fibrillation (AF) is associated with a transient increased risk of thromboembolic and hemorrhagic events. We hypothesized that dabigatran can be safely used as an alternative to continuous warfarin for the peri-procedural anticoagulation in PVI. Methods and Results 999 consecutive patients undergoing PVI were included; 376 patients were on dabigatran (150 mg) and 623 were on warfarin with therapeutic INR. Dabigatran was held 1 to 2 doses prior to PVI and restarted at the conclusion of the procedure or as soon as patients were transferred to the nursing floor. Propensity score matching was applied to generate a cohort of 344 patients in each group with balanced baseline data. Total hemorrhagic and thromboembolic complications were similar in both groups, before (3.2% vs 3.9%; p = 0.59), and after (3.2% vs 4.1%; p = 0.53) matching. Major hemorrhage occurred in 1.1% vs 1.6% (p = 0.48) before, and 1.2% vs 1.5% (p = 0.74) after matching in the dabigatran vs warfarin group respectively. A single thromboembolic event occurred in each of the dabigatran and warfarin groups. Despite higher doses of intra-procedural heparin, the mean ACT was significantly lower in patients who held dabigatran for 1 or 2 doses than those on warfarin. Conclusions Our study found no evidence to suggest a higher risk of thromboembolic or hemorrhagic complications with use of dabigatran for peri-procedural anticoagulation in patients undergoing PVI compared to uninterrupted warfarin therapy.