Detection of LA and LAA Thrombus by CMR in Patients Referred for Pulmonary Vein Isolation

OBJECTIVES: The goal of this study was to evaluate the diagnostic performance of a comprehensive, multicomponent cardiac magnetic resonance (CMR) study for assessment of left atrial (LA) and left atrial appendage (LAA) thrombus. BACKGROUND: Pre-operative evaluation for pulmonary vein isolation (PVI) typically requires tomographic imaging to define pulmonary venous anatomy and transesophageal echocardiogram (TEE) to assess for the presence of LA/LAA thrombus. CMR is increasingly being used to define pulmonary venous anatomy before PVI. Limited data are available on the utility of a multicomponent CMR protocol in assessing LA/LAA thrombus. METHODS: We studied patients who underwent multicomponent CMR for evaluation of pulmonary venous anatomy before PVI and underwent TEE within 7 days. LA and LAA thrombi were evaluated by using CMR as follows: 1) cine-CMR; 2) contrast-enhanced magnetic resonance angiography; and 3) equilibrium phase delayed enhancement (DE) CMR with a long inversion time (TI) of 600 ms (long TI DE-CMR). Components of the CMR study were evaluated for diagnostic performance for detection of LA or LAA thrombus using TEE as the reference standard. RESULTS: During the study period, 261 patients were assessed. The median CHA2DS2VASc (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke/transient ischemic attack, vascular disease, age 65 to 74 years, sex category) score was 2, and 73.6% of patients were undergoing anticoagulation therapy. CMR and TEE were performed within 1.3 ± 2.3 days. LA/LAA thrombi were discovered in 9 patients (3.5%) by using TEE. Among the CMR techniques performed, long TI DE-CMR had the highest diagnostic accuracy (99.2%), sensitivity (100%), and specificity (99.2%), followed by contrast-enhanced magnetic resonance angiography (accuracy 94.3%; sensitivity 66.7%; and specificity 95.2%) and cine-CMR (accuracy 91.6%; sensitivity 66.7%; and specificity 92.5%). CONCLUSIONS: In patients referred for PVI, CMR could be a single complete diagnostic study for assessment of pulmonary venous anatomy as well as presence of LA/LAA thrombi, thus reducing the number of pre-operative tests before PVI. Long TI DE-CMR has the best diagnostic performance and should be used for the detection of LA/LAA thrombi.