Progressnotes - October/November 2012
- About MUSC Health
Atrial fibrillation (AF), the most common cardiac arrhythmia, is characterized by erratic beating of the heart’s upper chambers (atria), often leading to a very rapid heart rate and impeding blood flow from the atria into the lower chambers of the heart (ventricles). This lack of mechanical contraction in the atria can lead to pooling of blood, increasing the risk of clot formation and embolism with stroke if the clot breaks loose and travels to the brain.
Approximately 90% of clots in nonvalvular AF occur in the left atrial appendage (LAA), a finger-shaped pouch that extends from the left atrium. Observational studies show a lower risk of stroke in patients in whom the LAA has been excluded, either surgically or percutaneously, but randomized controlled trials are needed to establish a causal link. Anticoagulant therapy remains the first-line treatment for patients with AF; however, as many as 50% of patients with AF are not treated with anticoagulation because they have a history of bleeding episodes or a stroke while on these medications, their international normalized ratio is hard to regulate, or they have a perceived risk of falls or bleeding. For these patients, especially those with other risk factors for stroke like diabetes, heart failure, or advanced age, exclusion of the LAA may offer an attractive nonpharmacological and noninvasive treatment option.
MUSC currently offers these patients LAA ligation using the Lariat™ Suture Delivery System (SentreHEART, Inc., Redwood City, CA). According to Frank A. Cuoco Jr, M.D., Assistant Professor of Cardiology at MUSC, the advantages of this over other modalities of LAA exclusion, such as surgical removal or percutaneously placed vascular plugs, are that it is less invasive and “it leaves nothing inside the heart.”
The LARIAT system lassoes and ligates the LAA from inside the pericardial space; the LAA is then left to resorb naturally. The procedure, which is performed under general anesthesia, uses two magnet-tipped wires, one of which is inserted via catheter into the LAA along with a balloon to serve as a marker, and the other of which is introduced via a dry tap into the epicardial space. The attraction between the two magnets forms a rail, allowing the Lariat snare to be positioned around the LAA opening and then cinched shut. Ligation completeness is verified with transesophageal echocardiography and contrast fluoroscopy. The Lariat procedure thereby achieves LAA exclusion without requiring a surgical incision or device implantation.
Dr. Cuoco will also be the principal investigator for a multicenter clinical trial of an investigational vascular plug (the Amplatzer Amulet; St. Jude Medical, St Paul, MN) that blocks the opening of the LAA, potentially preventing clots from traveling to the brain.
This article originally appeared in the May 2013 issue of Progressnotes.