Cardiovascular magnetic resonance (CMR) could serve as a single diagnostic tool to assess pulmonary venous anatomy and presence of left atrial and left atrial appendage (LA/LAA) thrombus, reducing the number of tests prior to pulmonary vein isolation (PVI), according to data published in JACC: Cardiovascular Imaging.
In addition, the best diagnostic performance was yielded from equilibrium phase delayed enhancement (DE) CMR using long inversion time (TI) of 600 ms (long TI DE-CMR), and researchers determined this method should be used for LA/LAA thrombus detection.
Transesophageal echocardiogram (TEE) is currently the standard method for detecting LA/LAA in patients with atrial fibrillation (AF) prior to PVI. However, CMR imaging has been validated as an effective detection method for left ventricular thrombus, and is becoming another reliable imaging modality. Therefore, researchers sought to determine the diagnostic efficacy of CMR in LA/LAA detection.
“In patients referred for PVI, CMR is a non-invasive test that has a favorable diagnostic performance and could be an alternative imaging modality to TEE for assessment of LA/LAA thrombus,” they wrote.
A total of 261 patients underwent multicomponent CMR for evaluation of pulmonary venous anatomy prior to PVI as well as TEE within 7 days. Researchers evaluated LA/LAA thrombus with CMR using TI DE CMR. They also used TEE as a reference standard to assess the diagnostic performance of CMR for detection of LA/LAA.
Throughout the study period, 73.6% of the patients were on anticoagulation medication, and the median CHA2DS2VASc Score was 2. CMR and TEE were performed within 1.3 ± 2.3 days, and LA/LAA thrombi were discovered in 9 patients (3.5%) via TEE.
Of all the CMR techniques that were performed during the study, TI DE-CMR had the highest diagnostic accuracy of 99.2%. This method also yielded the highest sensitivity (100%) and specificity (95.2%).
The contrast-enhanced MRA technique had the next highest level of accuracy and sensitivity (94.3% and 66.7%, respectively with 95.2% specificity) and lastly, the cine CMR technique had the lowest levels of accuracy and sensitivity (91.6% and 66.7%, respectively with 92.5% specificity).
The authors noted that in the current study, unlike TEE, which provides anatomical and physiological data like LAA emptying velocity, CMR could only provide anatomical data. They suggested that these findings may be confirmed with additional studies conducted across multiple centers and with larger sample sizes.
“In contrast to cardiac CT [computed tomography], CMR could provide valuable data for PVI procedure without exposure to radiation,” they concluded. “This might be even more important in certain patients that are expected to have long PVI procedure time or a repeat procedure in the future.”
Kitkungvan D, Nabi F, Ghosn MG, et al. Detection of left atrial and left atrial appendage thrombus by cardiovascular magnetic resonance in patients referred for pulmonary vein isolation. JACC Cardiovasc Imaging. 2016. doi: 10.1016/j.jcmg.2015.11.029.