Quantitative Evaluation of the Substantially Variable Morphology and Function of the Left Atrial Appendage and Its Relation with Adjacent Structures

RESEARCH ARTICLE Quantitative Evaluation of the Substantially Variable Morphology and Function of the Left Atrial Appendage and Its Relation with Adjacent Structures Cai-Ying Li1☯*, Bu-Lang Gao2☯*, Xiao-Wei Liu1, Qiong-Ying Fan2, Xue-Jing Zhang2, GuoChao Liu2, Hai-Qing Yang1, Ping-Yong Feng1, Yong Wang1, Peng Song1 1 Department of Medical Imaging, Second Hospital, Hebei Medical University, Shijiazhuang, Hebei Province, PR China, 2 Department of Medical Research, Shijiazhuang First Hospital, Hebei Medical University, Shijiazhuang, Hebei Province, PR China ☯ These authors contributed equally to this work. * (CYL); (BLG) Abstract Objective OPEN ACCESS Citation: Li C-Y, Gao B-L, Liu X-W, Fan Q-Y, Zhang X-J, Liu G-C, et al. (2015) Quantitative Evaluation of the Substantially Variable Morphology and Function of the Left Atrial Appendage and Its Relation with Adjacent Structures. PLoS ONE 10(7): e0126818. doi:10.1371/journal.pone.0126818 Editor: Carmine Pizzi, University of Bologna, ITALY Received: December 30, 2014 Accepted: April 8, 2015 Published: July 31, 2015 Copyright: © 2015 Li et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper. Funding: The authors have no support or funding to report. Competing Interests: The authors have declared that no competing interests exist. To investigate quantitatively the morphology, anatomy and function of the left atrial appendage (LAA) and its relation with adjacent structures. Materials and Methods A total of 860 patients (533 men, 62.0%, age 55.9±10.4 year) who had cardiac multidetector computed tomography angiography from May to October 2012 were enrolled for analysis. Results Seven types and 6 subtypes of LAA morphology were found with Type 2 being the most prevalent. Type 5 was more significantly (P<0.05) present in women (8.0%) than in men (4.2%). LAA orifice was oval in 81.5%, triangular in 7.3%, semicircular in 4%, water droplike in 3.2%, round in 2.4% and foot-like in 1.6%. The LAA orifice had a significantly greater (P<0.01) major axis in men (24.79±3.81) than in women (22.68±4.07). The LAA orifice long axis was significantly (P<0.05) positively correlated with the height, weight and surface area of the patient. The LAA morphology parameters displayed strong positive correlation with the left atrium volume, aortic cross area long axis or LSPV long axis but poor correlation with the height, weight, surface area and vertebral body height of the patients. Four types of LAA ridge were identified: AI, AII, B and C with the distribution of 17.6%, 69.9%, 5.9% and 6.6%, respectively. The LAA had a significantly (P<0.05) greater distance from its orifice to the mitral ring in women than in men. The LAA had two filling and two emptying processes with the greatest volume at 45% phase but the least volume at 5% phase. The LAA maximal, minimal and emptying volumes were all significantly (P<0.05) positively correlated with PLOS ONE | DOI:10.1371/journal.pone.0126818 July 31, 2015 1 / 19 Evaluation of the Left Atrial Appendage and Adjacent Structures the body height, weight and surface area, whereas the LAA ejection fraction had an inverse correlation with the LAA minimal volume but no correlation with the maximal volume. Conclusion The LAA has substantially variable morphologies and relation with the adjacent structures, which may be helpful in guiding the LAA trans-catheter occlusion or catheter ablation procedures. Introduction Cardiac arrhythmias comprise an important public health problem significantly associated with elevated risks of sudden death and cardiovascular complications, subsequently leading to decreased quality of life, disability, high mortality and massive healthcare expenses[1–3]. Atrial fibrillation is the most common sustained cardiac arrhythmia encountered in daily clinical practice, affects over 2.3 million people in the United States and has been increasingly on the rise with ageing of the society[2, 3]. The current prevalence of atrial fibrillation in the general population is 0.5%-1% and goes up to approximately 10% for those who are 80 years of age or above in the Western countries[4–7]. Data from some Asian countries including China showed a lower prevalence of atrial fibrillation (0.2%-1.5%)[3, 8]. However, since Asia is the most populated area in the world, the burden of atrial fibrillation in Asia may actually exceed that in Western countries. Atrial fibrillation carries a significantly increased risk of stroke, and the risk of stroke rises approximately 5-fold in non-rheumatic atrial fibrillation and 17-fold in patients with mitral stenosis and atrial fibrillation[7, 9]. Around 15% of ischemic strokes are caused by atrial fibrillation, and 90% of atrial thrombi in non-rheumatic atrial fibrillation and 60% of such thrombi in patients with rheumatic mitral valve stenotic diseases originate from within the left atrial appendage (LAA)[9, 10]. Cardioembolic stroke is the most serious and life threatening potential complication of atrial fibrillation, with an associated mortality up to 30% at 12 months and a 1/3 recurrence rate at 5 years [11, 12]. Stroke prevention thus plays a socioeconomically highly important role in atrial fibrillation management. Currently, the most established prophylaxis for stroke in atrial fibrillation is the dose-modulated oral anticoagulation with vitamin-K-antagonists, with warfarin being the most widely investigated drug[11]. Of note, it is often difficult to maintain long-term anticoagulation within a narrow therapeutic range partly because of regular laboratory monitoring of anticoagulation intensity, frequent dose adjustment and higher risks of bleeding during anticoagulation [13, 14]. Patients with atrial fibrillation, high risk of stroke and contraindications to long-term oral administration of anticoagulants due to hemorrhage or other secondary adverse effects may be candidates for alternative treatment that combines high efficacy in stroke prevention and low hemorrhage risk. The frequency of thrombus formation in LAA and the dominant role of LAA as a source of embolism in patients with atrial fibrillation led to the hypothesis that resection or obliteration of the LAA might decrease the risk of stroke [15, 16]. However, due to the invasive nature of surgery, surgical elimination of LAA is only performed as an adjunctive procedure in patients undergoing mitral valve surgery[17]. Moreover, surgical LAA exclusion is incomplete in 1/3 to 1/2 patients[16, 18]. Thus, the development of less invasive percutaneous approaches to completely obliterate the LAA via trans-catheter delivery of a mechanical device is a great step ahead in this field, and this catheter-delivered mechanical device may allow for direct prevent (...truncated)