Abstract & Commentary
Synopsis: This procedure can be performed safely and may be effective in reducing stroke in high-risk patients who cannot take anticoagulants.
Source: Blackshear JL, et al. J Am Coll Cardiol. 2003;42:1249-1252.
In this study, Blackshear and colleagues report on their experience with thoracoscopic surgical techniques to close the left atrial appendage as prophylaxis against stroke in patients with atrial fibrillation. Patients were considered for inclusion in the study if they had atrial fibrillation with at least 1 risk factor for stroke and had either an absolute contraindication to warfarin or some documentation of prior left atrial appendage thrombosis during adequate oral anticoagulation. For the procedure, patients were taken to the operating room and placed under general anesthesia. Thoracoscopic incisions were made to introduce video-thoracoscopic instruments. The volume of the left lung was reduced using a double lumen endotracheal tube and carbon dioxide insufflation into the left pleural space. The left atrial appendage tip was grasped using a nontraumatic clamp and a snare placed at the appendiceal base where it was cinched to occlude the appendage. In some patients, staples were used in place of the loop. Patients were followed by clinic visits and telephone after the procedure. The primary end point was death or an embolic event.
Fifteen patients were included in the study. They ranged in age from 24 to 81, with a median of 71 years. Eleven of the patients had a history of prior thromboembolism. Hypertension was reported in 12 patients. Eleven patients had a history of significant intracerebral (5) or gastrointestinal (6) bleeding, and one had prior surgery for a meningioma. Successful occlusion of the atrial appendage was noted in the operating room in all patients, but chronic occlusion was not documented since follow-up imaging was not performed.
There were no perioperative neurologic events. During a median follow-up of 42 months, there were 2 strokes. One patient had a small nonfatal stroke during a hospitalization for pneumonia 3 months after the procedure. He had no subsequent events during a further 37 months of follow-up. One patient had a fatal stroke with intracranial hemorrhage 55 months after surgery. The estimated stroke rate was 4% per year, with a rate of fatal stroke of 2% per year.
Blackshear et al conclude that this procedure can be performed safely and may be effective in reducing stroke in high-risk patients who cannot take anticoagulants.
Comment by John DiMarco, MD, PhD
In patients with atrial fibrillation, the left atrial appendage is thought to be a common source for thromboemboli. During atrial fibrillation, there is reduced flow velocity in the left atrial appendage, and between 10% and 20% of patients with atrial fibrillation have intracardiac thrombus in the left atrial appendage when examined by transesophageal echocardiogram (TEE) or at autopsy.
It has clearly been shown that warfarin reduces the incidence of stroke in patients with nonvalvular atrial fibrillation when additional risk factors for stroke are present. Unfortunately, up to one-third of patients initially screened for participation in these trials had absolute or strong relative contraindications to anticoagulation, and at least this proportion of patients who are poor candidates for chronic anticoagulation is seen in clinical practice. Even if contraindications to anticoagulation are not present when therapy is started, 10-20% of patients will discontinue anticoagulation during chronic therapy, usually due to the occurrence of bleeding. For these reasons, occlusion of the left atrial appendage that could be performed safely might offer an alternative to anticoagulation in selected high-risk individuals.
The data shown here are interesting but very preliminary. The study group included only 15 patients. With this small a group, it is impossible to estimate accurately the effects of the procedure of thromboembolic events. Therefore, this paper really only shows the feasibility of a thoracoscopic approach to left atrial appendage occlusion. There is also a competing technique, which is now undergoing investigation. This uses a nitinol occlusion device, which can be placed by catheter in the left atrial appendage. If this latter procedure proves to be safe and effective, it would obviate the need for even the minimally invasive approach here. Since most of the complications in this study were seen in the immediate perioperative period, the catheter-based approach may be preferred in truly critically ill patients.
Dr. DiMarco, Professor of Medicine in the Division of Cardiology at the University of Virginia, Charlottesville, is on the Editorial Board of Clinical Cardiology Alert.