Left Atrial Appendage Shape Linked to Stroke Risk in AF

Pauline Anderson

November 23, 2021

The shape of the left atrial appendage (LAA) is linked to risk of stroke and transient ischemic attack (TIA) in patients with atrial fibrillation (AF), results of a preliminary retrospective study show.

Depending on the form and structure of the LAA, the risk was increased by more than double or decreased by 68%, the researchers found.

A posted preprint of the study, led by Judit Simon, doctor of medicine and researcher PhD candidate, Semmelweis University, Budapest, Hungary, is a preliminary version of a manuscript that has not completed peer review. The results are published as a preprint at Research Square.

Among other factors, AF is an independent risk predictor for ischemic stroke and TIA. An estimated one third of patients with ischemic stroke have either clinical or subclinical AF, the authors note.

The LAA is a frequent source of cardiac thrombus responsible for stroke and TIA in patients with AF, and previous studies reported LAA morphology correlates with stroke and TIA in AF patients, they note.

This new study included 649 adult patients with drug-refractory AF, mean age 61.3 years and 33.9% female, who underwent cardiac CT before catheter ablation in the Heart and Vascular Center of Semmelweis University, Budapest, Hungary, between 2014 and 2017. Researchers accessed history of stroke/TIA from patient charts.

A maximum of 24 hours before ablation, all patients underwent a transesophageal echocardiographic (TEE) examination to exclude the presence of LAA thrombus.

Researchers measured LAA flow velocity, which reflects left atrial (LA) function, and determined LAA morphologies based on three-dimensional volume-rendered images. Since assessment of LAA morphologies can be highly subjective, these were determined by consensus reading by three expert readers using rigorous definitions.

The investigators classified LAA morphologies into four types: cauliflower (LAA has limited length and the distal width exceeds the proximal width); windsock (primary structure is one dominant lobe with sufficient length); chicken wing (the dominant lobe has an obvious bend in the proximal or middle part); and swan (the LAA has a second sharp curve folding the dominant lobe back).

Some 7.1% of study subjects had a prior stroke/TIA (2.3% had TIA and 4.8% had ischemic stroke). The prevalence of cauliflower, windsock, chicken wing, and swan morphologies were 50.2%, 32.5%, 12.4%, and 4.8% in patients without prior stroke/TIA vs 63.0%,13.0%, 8.7% and 15.2% in those with prior stroke/TIA, respectively (P = .002).

After adjustments for risk factors, swan LAA shape was associated with a more than 2.5-fold risk of stroke/TIA (multivariate odds ratio [OR], 2.69; 95% CI, 0.96 – 6.86; P = .047), while windsock morphology was associated with a decrease in risk by 68% (multivariate OR, 0.32; 95% CI, 0.12 – 0.77; P = .017).

"To our knowledge, this is the first study to correlate cauliflower, chicken wing, swan and windsock morphologies with the history of stroke/TIA in AF patients," the authors write.

The anatomic morphology of the LAA is highly variable, they note. Some previous studies did not find an association between LAA morphology and the risk of ischemic stroke but used different categories of LAA morphologies.

LAA flow velocity has been reported as a quantitative surrogate parameter for thromboembolic risk. In this study, LAA flow velocity ≤35.3 cm/sec doubled the odds of stroke/TIA (OR, 2.18; 95% CI, 1.09 – 4.61; P = .033).

This single-center, retrospective study needs confirmation in multicenter prospective studies, the researchers note.

They caution that the type of stroke and medications taken at the time of stroke/TIA could not be recorded in all patients. Another limitation was that stroke/TIA rates were small, since the study was limited to AF patients undergoing catheter ablation.

As well, it's impossible to prove all strokes and TIAs were of cardiac origin, "but this is inherent to all studies focusing on this topic," they concluded.

The preprint is under consideration at The International Journal of Cardiovascular Imaging. A preprint is a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice. The research was financed by the Thematic Excellence Programme of the Ministry for Innovation and Technology in Hungary, within the framework of the Therapeutic Development and Bioimaging thematic programmes of the Semmelweis University.

The authors have no relevant conflicts of interest.

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