Detection of left atrial thrombus during routine diagnostic work-up prior to pulmonary vein isolation for atrial fibrillation: Role of transesophageal echocardiography and multidetector computed tomography☆
Introduction
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and is associated with increased morbidity and mortality as well as decreased quality of life [1], [2]. Catheter ablation of AF has evolved over the past decade and is currently recommended for symptomatic patients who are refractory to drug therapy [3]. Imaging of the LA and related intrathoracic structures prior to ablation is important for procedural planning [4], [5]. Multidetector computed tomography (MDCT) allows visualization of the entire left atrium (LA), including the left atrial appendage (LAA) and the number and anatomy of the pulmonary veins. In addition, pre-segmented 3D-MDCT data sets might be integrated with advanced electroanatomical mapping systems to assist during the mapping and ablation procedure, and to avoid complications [6].
Thromboembolism, usually originating from the LA and LAA, is a major complication of AF and may result in transitory ischemic attack (TIA) and stroke [1]. The presence of LA/LAA thrombus is a contraindication to catheter ablation of AF since navigation of ablation catheters inside the LA may lead to the dislodgement of in situ thrombi [3]. Accordingly, the 2007 Heart Rhythm Society/European Heart Rhythm Association/European Cardiac Arrhythmia Society consensus statement recommends pre-procedural transesophageal echocardiography (TEE) in order to screen for the presence of thrombus, especially in patients with persistent AF at the time of ablation [3]. Although TEE is still considered the gold standard to exclude LA/LAA thrombus, recent studies have investigated the usefulness and limitations of MDCT in excluding LA/LAA thrombus [7], [8], [9], [10], [11], [12], [13], [14]. However, the results are conflicting and diagnostic accuracy has varied widely between studies. It has further been demonstrated that LA/LAA thrombus may form during effective oral anticoagulation with a vitamin K antagonist such as phenprocoumon [15]. However, the prevalence of LA/LAA thrombus also varies between different reports and recommendations regarding TEE screening in patients with paroxysmal AF or low-risk profile are less clear [3], [16], [17], [18].
The aim of this study was to prospectively analyze the diagnostic yield of routine pre-procedural TEE and cardiac MDCT in patients undergoing pulmonary vein isolation (PVI) and to identify predictors of LA/LAA thrombus formation despite effective anticoagulation.
Section snippets
Patient population
A single-center study was done in 329 patients with drug-refractory, symptomatic paroxysmal or persistent AF scheduled to undergo PVI between October 2007 and April 2010 at the Heart Center of Georg-August-University Göttingen, Germany. All patients were included in a registry and all clinical, imaging and procedural data were prospectively recorded. Paroxysmal AF was defined as self-terminating episodes of AF lasting less than 7 days. Persistent AF was defined as AF sustained > 7 days, and
Patient characteristics
We enrolled 329 consecutive patients, aged 62 ± 10 years; 65% were men. The clinical characteristics of the entire study population are presented in Table 1. Most patients had paroxysmal AF (74%) and were anticoagulated at the time of TEE (78%). According to the CHADS2 score, the majority of patients fell into low- (CHADS2 0 = 22%) or intermediate-risk groups (CHADS2 1 = 50%). All patients underwent TEE and MDCT without complications. The actual prevalence of LA/LAA thrombus detected by TEE was 7/329
Main findings
Appropriate anticoagulation does not effectively prevent the formation of LA/LAA thrombus. In our patient population, LA/LAA thrombus was present in 2.1% of patients immediately prior to PVI. We found CHADS2 score ≥ 3, CHA2DS2-VASc scores ≥ 4, and diabetes mellitus to be predictors of the presence of LA/LAA thrombus. There were no cases of LA/LAA thrombus in patients with CHADS2 or CHA2DS2-VASc scores scores < 2. Compared to the gold standard of TEE, 64-slice MDCT was far less reliable in
Conclusion
Seven of 329 (2.1%) patients with AF undergoing TEE prior to PVI had LA/LAA thrombus despite effective anticoagulation. In comparison with TEE, 64-slice MDCT does not reliably exclude LA/LAA thrombus and one cannot confidently perform AF ablation in patients with thrombus negative MDCT scans despite a relatively strong negative predictability. CHADS2 score ≥ 3, CHA2DS2-VASc score ≥ 4, and diabetes mellitus were independent predictors for the presence of thrombus. Other factors, specifically LA
Acknowledgments
The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology.
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2019, CJC OpenCitation Excerpt :However, the present study may more closely reflect real-world anticoagulation practice because preprocedural INRs were not managed using a strict protocol and all patients underwent TEE regardless of anticoagulation status or preprocedural INR value. CHADS2 and CHA2DS2-VASc score have consistently been identified as predictors of LAA thrombus; however, the individual comorbidities of heart failure and prior CVA/TIA have shown varied results.13,23,27-33 Our study results were similar to those of Wysokinski et al.,32 who reported an increased odds of thrombus associated with congestive heart failure (OR, 5.12; 95% CI, 2.91-9.03) and prior stroke (OR, 2.56; 95% CI, 1.37-4.76).