LAA thrombi rare in PVI patients
CLEVELAND, OHIO. Suffering a stroke during or after a pulmonary vein isolation (PVI) procedure is fairly rare (approximately 1.5% incidence rate), but obviously constitutes a serious complication. To avoid stroke during the procedure, patients are usually pre-screened for clots in the left atrium (LA) and left atrial appendage (LAA) using CT scanning and/or transesophageal echocardiography (TEE). In addition, heparin is used during the procedure and warfarin after to avoid post-procedural stroke. It is not known just how frequent LA or LAA clots are found in patients prior to their PVI.

Electrophysiologists at the Cleveland Clinic have just published the results of a study involving 1221 afibbers who underwent a pulmonary vein antrum isolation during the period 2000-2004. All patients underwent a pre-procedure CT scan and 60 also underwent a TEE. Nine patients were found to have a thrombus (clot) in the LAA as per the CT scan; however, when checked with TEE only three were actually clots, while the remaining 6 were smoke-like echo.

Two of the 3 patients had permanent afib with an average left ventricular ejection fraction (LVEF) of 48%, while the sole paroxysmal afibbers with a clot had an ejection fraction of only 25%. Thus, no paroxysmal afibbers with an ejection fraction of 50% or greater (normal) experienced LAA thrombi. Inasmuch as lone afibbers, by definition, have normal LVEFs (50% or greater), there were no incidences of LAA clots in paroxysmal, lone afibbers. It is likely that the two permanent afibbers had underlying heart disease (average LVEF was 48%), so it is probably safe to assume that even permanent, lone afibbers would be very unlikely to have thrombi in the LAA.

The Cleveland EPs conclude that a pre-procedure CT scan may be all that is required and that the use of TEE may not be needed in the case of paroxysmal afibbers with normal (50% or greater) LVEF.

Khan, MN, et al. Low incidence of left atrial or left atrial appendage thrombus in patients with paroxysmal atrial fibrillation and normal EF who present for pulmonary vein antrum isolation procedure. Journal of Cardiovascular Electrophysiology, Vol. 19, April 2008, pp. 356-58

Editor's comment: This is good news indeed and confirms earlier research that lone afibbers are not prone to clot development in the LAA. As far as the CT scan or TEE is concerned, if given the choice, I would personally prefer the TEE so as to avoid the radiation inherent in CT scanning and the potential adverse effects of the contrast medium (x-ray dye) used during the scan.