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.