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.