Background:
Atrial fibrillation (AF) is the most common arrythmia in the US, with an
estimated prevalence of 1-2% (1), which increases with age to 20% in
patients in their 80s (2). One of the most feared complications in AF
patients is cardioembolic stroke (3), with studies suggesting case
fatality rates of up to 27% (4). Thus, current guidelines for the
treatment of AF involve a dual-strategy of rate/rhythm control for
prevention of arrythmia, as well as oral anticoagulation (OAC) for
mitigation of stroke risk (5). Prior data suggested that rate control
was non-inferior to rhythm control (AFFIRM trial)(6), recently early
rhythm control is proving to improve outcomes (EAST-AF, EARLY-AF)(7, 8).
Catheter ablation of AF has proven to be a safe and effective strategy
in drug-refractory AF patients. Recent trials have suggested that
ablation is superior to medication for reducing mortality in certain
subsets of AF patients (9) and that the former may also provide better
quality-of-life (10). However, the effect of catheter ablation on LA/LAA
morphology and function is poorly understood (11).
The left atrium (LA) serves a complex “trio” of functions, working as
a reservoir, conduit, and booster pump at different points of the
cardiac cycle (12). The LA’s relatively weaker contractility compared to
the left ventricle (LV) increases the possibility of blood stasis (13).
The left atrial appendage (LAA) is the most common source for the
formation of systemic thromboemboli due to its unique shape and
increased tendency for blood stasis (14).The entrance from the LA into
the LAA is the LAA ostium, which is usually defined by the coumadin
ridge superiorly and the left circumflex artery inferiorly (15). The LAA
ostium was initially studied and measured for developing techniques for
LAA occlusion (16), such as the use of ligation, clip or a Watchman™
device (17). However, detailed evidence is lacking on how baseline LAA
ostium characteristics are correlated with other anatomical and clinical
parameters of the LA and LAA in AF patients. Furthermore, there is a
paucity of data on how the LAA ostium changes after AF ablation. These
findings can help us better understand underlying mechanisms of LA/LAA
morphological changes following catheter ablation.
In this study we aim to assess baseline LAA ostium characteristics among
AF patients and correlate them with anatomical and functional parameters
of the LA and LAA, as well as patients’ preexisting comorbidities and
risk factors. We will also be the first to report changes in the LAA
ostium following AF catheter ablation.