Left atrial (LA) and left atrial appendage (LAA) thrombi can be detected with cardiac MRI — without an extra transesophageal echocardiogram (TEE) — before pulmonary vein isolation, a single-center study suggested.
Cardiac MRI with long inversion time delayed enhancement (long TI DE-CMR) independently picked up LA and LAA clots in the same 3.5% of patients as did gold-standard TEE, Dipan J. Shah, MD, of Houston Methodist DeBakey Heart & Vascular Center, and colleagues reported online in JACC: Cardiovascular Imaging.
Among the various cardiac MRI techniques, the long TI DE approach had the best diagnostic accuracy (99.2%), sensitivity (100%), and specificity (99.2%). Coming in second place was contrast-enhanced MR angiography (94.3%, 66.7%, 95.2%), followed by cine cardiac MRI (91.6%, 66.7%, 92.5%).
“In patients referred for pulmonary vein isolation, CMR could be a single complete diagnostic study to assess pulmonary venous anatomy as well as presence of LA/LAA thrombus, thus reducing the number of preoperative tests prior to pulmonary vein isolation,” the researchers concluded.
“Long TI DE-CMR has the best diagnostic performance and should be utilized for LA/LAA thrombus detection,” they suggested.
Warren J. Manning, MD, and Aferdita Spahillari, MD, both of Beth Israel Deaconess Medical Center in Boston, highlighted the growing interest in a one-stop imaging solution prior to pulmonary vein isolation.
“Despite being the gold-standard method for detection of atrial and atrial appendage thrombi, TEE is moderately invasive,” they wrote in an accompanying editorial.
“As TEE does not optimally image the pulmonary veins, patients routinely undergo both magnetic resonance angiography (or CT angiography) as well as TEE, increasing healthcare costs and patient inconvenience,” they added. “It would be much preferred to have a single noninvasive imaging modality that allowed for both pulmonary vein evaluation and exclusion of atrial and atrial appendage thrombi.”
The editorialists posed the question: “Could CMR displace TEE for exclusion of LA/LAA thrombus in patients prior to elective cardioversion from afib? This may be especially attractive for those with a relative contraindication to TEE (e.g., esophageal stricture, Zenker’s diverticulum) or at higher risk for conscious sedation (e.g., sleep apnea).”
But, “unlike TEE that could provide both anatomical and physiological data such as LAA emptying velocity, the evaluated CMR components in our study could only provide anatomical data,” Shah and colleagues acknowledged.
Cardiac MR also takes considerable time, they added, though they argued that it has the advantage of not exposing patients to ionizing radiation. And long TI DE-CMR “was not affected by the use of 1.5T or 3T scanner or presence of atrial fibrillation at the time of CMR procedure.”
Shah’s group reviewed the records of 261 atrial fibrillation patients who underwent both cardiac MR and TEE within a week prior to pulmonary vein isolation.
In addition to the single-center design, the investigators noted that omission of phase-sensitive inversion recovery DE-CMR from their study was a limitation. “Phase sensitive inversion recovery sequence could potentially be another alternative way of thrombus imaging that does not require additional TI adjustment,” they wrote. With this modality, clots “appear black and easy to identify.”
Manning and Spahillari suggested intracardiac echocardiography (ICE) as another way to image a patient in this setting.
“Though moderately invasive, ICE is often performed to guide transeptal puncture and to confirm catheter position during pulmonary vein isolation. It has shown promise in identifying anatomic structures such as pulmonary veins as well as detection of LA/LAA thrombus,” they wrote.
It remains to be seen “whether the findings are reproducible in a prospective multicenter setting,” the editorialists noted. They added that “while the study evaluated the inter-observer image agreement, it did not evaluate variability in CMR acquisition. Issues with image interpretation reproducibility are a widespread phenomenon in diagnostic imaging.”
“Furthermore, the diagnostic ability of CMR to detect right atrial or right atrial appendage thrombi was not assessed,” according to Manning and Spahillari.
Shah, Manning, and Spahillari disclosed no relevant relationships with industry.
JACC: Cardiovascular Imaging
Kitkungvan D, et al “Detection of left atrial and left atrial appendage thrombus by cardiovascular magnetic resonance in patients referred for pulmonary vein isolation” J Am Coll Cardiol Img 2016. DOI: 10.1016/j.jcmg.2015.11.029.
JACC: Cardiovascular Imaging
Manning WJ, Spahillari A “Combined pulmonary vein and left atrial/appendage thrombus assessment: can cardiovascular magnetic resonance kill two birds with one stone?” J Am Coll Cardiol Img 2016. DOI: 10.1016/j.jcmg.2015.12.017.