Heart Rhythm. 2013 Jun;10(6):921-5.

Anatomical characteristics of the left atrial appendage in cardiogenic stroke with low CHADS2 scores.

Kimura T, Takatsuki S, Inagawa K, Katsumata Y, Nishiyama T, Nishiyama N, Fukumoto K, Aizawa Y, Tanimoto Y, Tanimoto K, Jinzaki M, Fukuda K.

Department of Cardiology, Keio University School of Medicine, Tokyo, Japan. kimura@z7.keio.jp

 

Abstract

BACKGROUND: Strokes develop even in patients with low CHADS₂ scores, and the left atrial appendage (LAA) is the embolic source 90% of the time. We focused on the LAA morphology as a new predictor of strokes.

OBJECTIVE: To clarify the anatomical characteristics of the LAA for risk stratification of strokes in patients with nonvalvular atrial fibrillation (AF) who have low CHADS₂ scores.

METHODS: Among 80 patients who underwent catheter ablation of AF with contrast-enhanced computed tomography, the LAA characteristics were compared between 30 patients with histories of strokes and 50 age-matched controls. The LAA anatomy was classified into 4 types–“cactus,” “cauliflower,” “chicken wing,” and “windsock”–discriminated by the computed tomography measurements of the length, angle, and number of lobes of the LAA.

RESULTS: The average CHADS₂ score did not differ significantly between patients with stroke and controls (0.8 ± 0.8 vs 0.6 ± 0.7; P = .277). Eight (26.7%) patients with stroke had CHA₂DS₂-VASc scores of 0. The left atrial size, LAA flow velocity, left ventricular function, and serum brain natriuretic peptide level were also unable to predict strokes. However, a “cauliflower” LAA, defined as a main lobe of less than 4 cm long without forked lobes, was significantly more common in patients with stroke (odds ratio 3.857; 95% confidence interval 1.482-10.037; P = .005). The CHA₂DS₂-VASc score-adjusted logistic regression analysis revealed the cauliflower LAA as an independent predictor of a stroke (odds ratio 3.355; 95% confidence interval 1.243-9.055; P = .017).

CONCLUSIONS: The LAA anatomy might be useful for predicting strokes in patients with nonvalvular AF who have low CHADS₂scores.

Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc.

PMID: 23384894

 

Supplements:

Which patients have an absolutely low risk of stroke with atrial fibrillation (AF)?

There remains no clear answer to this question. The decision to initiate oral anticoagulants is usually based on risk-scoring systems, such as the CHADS2 score 1 or CHA2DS2-VASc score 2, and the annual rate of stroke or thromboembolism is reportedly 0.84% per year in patients with a CHA2DS2-VASc score of 0 3. While this seems low, such a risk cannot be ignored.

The left atrial appendage (LAA) accounts for 90% of the emboli underlying cardiogenic strokes. It is therefore important to predict high-risk LAAs, since we sometimes experience LAA thrombi in patients with a CHADS2 score of 0, as well as patients who have a history of a stroke with a CHA2DS2-VASc score of 0. However, parameters of the LAA have not yet been concerned as standard scoring factors.

Direct closure of the LAA, the ultimate solution for an embolic source, with devices such as the WATCHMAN 4, AtriClip 5, and LARIAT 6, is reportedly non-inferior to vitamin K antagonists. The recent heightened interest in direct closure of the LAA has also increased the attention given to LAA morphology. Wang et al. [16] evaluated the efficacy of CT imaging toward the preoperative planning and implantation of LAA closure according to four morphological classifications: Cactus, Cauliflower, Chicken Wing, and Windsock. However, the critical decision for discriminating the LAA morphology is so subjective that some could have been misclassified as having a Cauliflower morphology instead of a Windsock. Therefore, we added quantitative measurements to minimize the inter-observer variability by measuring the length of the main lobe, angle of the main lobe, and the number of lobes. We newly proposed the LAA morphological criteria to be defined as follows: Cactus; a main lobe length of < 4 cm, with more than 2 lobes over 1 cm in length; Cauliflower: a main lobe length of < 4 cm, without any forked lobes; Chicken wing: a main lobe length of > 4 cm, with a folded angle of < 100o; Windsock: a main lobe length of > 4 cm, with a folded angle of > 100o (Supplemental Figure). As a result, among 80 patients from a cohort of 340 AF patients undergoing catheter ablation, we compared the LAA characteristics among 30 patients with a prior history of stroke and 50 age-matched control patients 7. We found that the Cauliflower LAA morphology was significantly more common in the stroke patients than in controls (OR: 3.857, 95% CI: 1.482 to 10.037, P = 0.005). A logistic regression analysis controlled for the CHA2DS2-VASc score further revealed that the Cauliflower morphology was an independent predictor of a stroke (OR: 3.355, 95% CI: 1.243 to 9.055, P = 0.017). The average CHADS2 score did not significantly differ between the groups, and surprisingly, 8 stroke patients (26.7%) had a CHA2DS2-VASc score of 0, and 4 of these showed a Cauliflower-type LAA morphology. Other known risk parameters such as the size of the left atrium, left ventricular function, and serum brain natriuretic peptide level failed to predict a stroke.

We used only the four classifications described to categorize LAAs in this study, with no anomaly or accessory LAAs. However, there must have been some unclassified LAAs, such as a Cauliflower LAA with a huge orifice or an enormous Windsock LAA with a spontaneous echo contrast in the LAA tip. For a refined LAA classification system that reflects all observable morphological and functional characteristics, a larger cohort study with long-term follow-up is required to fully elucidate the value of such a risk stratification based soley on LAA morphology. In addition, parameters also affecting the stroke risk such as heart rate, left ventricular ejection fraction, degree of mitral regurgitation and duration of AF should be considered in any multivariate analysis. Finally, the LAA classification should be recognized as a predictor of a stroke, especially in patients with a low CHA2DS2-VASc score.

Can anatomical characteristics be used to predict a stroke in non-valvular AF patients? As of yet, not by themselves; however, it is still worth knowing whether the patient has a hazardous LAA.

Takehiro Kimura-1

Corresponding Address: 

Takehiro Kimura, MD, PhD

35 Shinanomachi Shinjuku-ku, Tokyo, JAPAN 160-8582

Department of Cardiology

Keio University School of Medicine

Tel: +81-3-3353-1211, Fax: +81-3-5363-3875

E-mail: kimura@z7.keio.jp

References

1.         Gage BF, Waterman AD, Shannon W, Boechler M, Rich MW, Radford MJ. Validation of clinical classification schemes for predicting stroke: Results from the national registry of atrial fibrillation. JAMA. 2001;285:2864-2870

2.         Lip GY, Frison L, Halperin JL, Lane DA. Identifying patients at high risk for stroke despite anticoagulation: A comparison of contemporary stroke risk stratification schemes in an anticoagulated atrial fibrillation cohort. Stroke. 2010;41:2731-2738

3.         Olesen JB, Torp-Pedersen C, Hansen ML, Lip GY. The value of the cha2ds2-vasc score for refining stroke risk stratification in patients with atrial fibrillation with a chads2 score 0-1: A nationwide cohort study. Thrombosis and haemostasis. 2012;107:1172-1179

4.         Holmes DR, Reddy VY, Turi ZG, Doshi SK, Sievert H, Buchbinder M, Mullin CM, Sick P. Percutaneous closure of the left atrial appendage versus warfarin therapy for prevention of stroke in patients with atrial fibrillation: A randomised non-inferiority trial. Lancet. 2009;374:534-542

5.         Ailawadi G, Gerdisch MW, Harvey RL, Hooker RL, Damiano RJ, Jr., Salamon T, Mack MJ. Exclusion of the left atrial appendage with a novel device: Early results of a multicenter trial. J Thorac Cardiovasc Surg. 2011;142:1002-1009, 1009 e1001

6.         Bartus K, Han FT, Bednarek J, Myc J, Kapelak B, Sadowski J, Lelakowski J, Bartus S, Yakubov SJ, Lee RJ. Percutaneous left atrial appendage suture ligation using the lariat device in patients with atrial fibrillation: Initial clinical experience. Journal of the American College of Cardiology. 2012

7.         Kimura T, Takatsuki S, Inagawa K, Katsumata Y, Nishiyama T, Nishiyama N, Fukumoto K, Aizawa Y, Tanimoto Y, Tanimoto K, Jinzaki M, Fukuda K. Anatomical characteristics of the left atrial appendage in cardiogenic stroke with low chads(2) scores. Heart rhythm : the official journal of the Heart Rhythm Society. 2013

Multiselect Ultimate Query Plugin by InoPlugs Web Design Vienna | Webdesign Wien and Juwelier SchönmannMultiselect Ultimate Query Plugin by InoPlugs Web Design Vienna | Webdesign Wien and Juwelier Schönmann