LAA Closure at Other Surgery Reduces Embolic, Mortality Risk in AF: STS Registry

Marlene Busko

March 31, 2017

WASHINGTON, DC — In a large observational study of Medicare patients with atrial fibrillation (AF) who had CABG or heart-valve surgery, those who had surgical left atrial appendage (LAA) closure at the same time had a 38% lower rate of thromboembolism and a 15% lower rate of all-cause mortality than other patients, in a 1-year follow-up[1].

Only patients who were discharged without an oral anticoagulant had a lower risk of thromboembolism (defined as thromboembolic stroke, systemic embolism, or transient ischemic attack [TIA]), the primary outcome.

Thus, "although randomized trial data are needed, this study does support the concept of left atrial appendage occlusion at the time of cardiac surgery, " said Dr Daniel J Friedman (Duke Clinical Research Institute, Durham, NC) at a press conference after he presented this study at the American College of Cardiology (ACC) 2017 Scientific Sessions.

                                                               

           

Dr Daniel Friedman

           

This was the largest observational study in a representative national population, and "it certainly moves the needle to increase awareness that surgical LAA occlusion should be a strategy we should consider actively, but we should also wait for some controlled randomized data for this," echoed the assigned discussant at the press conference, Dr Jagmeet Singh (Harvard Medical School, Boston, MA).

"It does . . . suggest to me in an observational study that if surgeons can do a good left atrial appendage occlusion, it may have a benefit," session panelist Dr Kenneth A Ellenbogen (Virginia Commonweath University School of Medicine, Richmond) told heartwire from Medscape.

Friedman and other experts cautioned that the results do not imply that high-risk patients who have had LAA closure should forgo anticoagulants, since the appendage could reconnect or a clot that causes a stroke could originate elsewhere.

Older Patients in STS Database

The researchers examined data from Medicare beneficiaries with AF who were part of the Society of Thoracic Surgeons (STS) adult cardiac surgery database and had cardiac surgery during 2011–2012.

They identified 10,524 patients with AF who had CABG (35%), mitral-valve surgery with or without CABG (35%), or aortic-valve surgery with or without CABG (30%) in more than 1000 institutions in the US.

The patients had a mean age of 76 and 39% were female. They had a median CHA2DS2-VASc score of 4 (interquartile range 3–5).

More than a third of the patients (3892 patients, 37%) underwent LAA closure, which "could have been done either with a clip or oversewing with or without amputation," Friedman said. 

Compared with other patients, those who had surgical LAA occlusion were less likely to be hospitalized for a thromboembolic event during a 1-year follow-up (1.6% vs 2.5%, respectively) or die from any cause during follow-up (7.0% vs 10.8%, respectively).

After adjustment for risk factors, having LAA closure was associated with a significantly lower risk of thromboembolism, all-cause mortality, or a composite outcome (thromboembolism, hemorrhagic stroke, or all-cause mortality).

Risk of 1-year Outcomes With vs Without LAA Occlusion Added on to Cardiac Surgery

Outcome Adjusted HR (95%CI) P
Thromboembolisma 0.62 (0.46–0.83) 0.001
Hemorrhagic stroke 0.64 (0.26–1.56) 0.33
All-cause mortality 0.85 (0.74–0.97) 0.015
Compositeb 0.70 (0.70–0.90) 0.002
Thromboembolism=thromboembolic stroke, systemic embolism, or transient ischemic attack; the primary outcome.
Composite=thromboembolism, hemorrhagic stroke, or all-cause mortality

Of the 3848 patients who were discharged with no anticoagulation, those who had LAA occlusion had a 71% lower risk of thromboembolism compared with patients who did not have LAA occlusion—but there was no significant association between LAA occlusion and thromboembolism among those discharged with anticoagulation.

At the time of the study, patients who received an anticoagulant generally received warfarin, not a novel oral anticoagulant.

Anticoagulants Still Needed

"I think we need to keep in mind that afib patients have stroke for a lot of different reasons," Friedman stressed. Clots can come from the left atrium in general or from the aorta or from the left ventricle. "Systemic anticoagulation is able to treat a number of different causes of stroke . . . so it's not quite as simple as 'we've treated the left atrium, now we're done with treating stroke.' "

LAA occlusion may be one of perhaps a few long-term antithrombotic strategies, including anticoagulant therapy, he added.

"It's really important to recognize that AF is more than a disease that is limited to the left atrial appendage, and if somebody has a fairly high CHA2DS2-VASc score . . . I may at this stage still be inclined toward continuing anticoagulation," Singh echoed.

"Surgical occlusion of the left atrial appendage is not without problems itself," he added. "Although the safety of this intervention has been improved beyond measure, we do know that sometimes surgical occlusions can be incomplete and often those can be prothrombotic in a small minority of patients."

If the LAA is stitched off during surgery, in 15% to 20% of cases, it reconnects, which invariably leads to a clot in the appendage, press conference moderator Dr John Fisher (Albert Einstein College of Medicine; New York City) added to heartwire .

Thus, even with a satisfactory occlusion of the appendage "we would probably continue the patient on anticoagulation, at least for the foreseeable future, with lots of monitoring for AF," he said.

Discuss the Option With Patients

"I think a randomized controlled trial actually looking at this in a long-term prospective fashion will truly answer this question," said Singh.

"I do think a randomized trial is necessary," Friedman stressed. "Observational data, no matter how well put together, shouldn't substitute for a clinical trial. And this is really a tremendously important question that affects so many patients."

Dr Richard Whitlock (Population Health Research Institute/McMaster University, Hamilton, ON) and colleagues are conducting a randomized trial to examine this, the Left Atrial Appendage Occlusion Study III (LAAOS III), he noted, with study completion estimated in 2020.

It's important for patients who are scheduled to have open-heart surgery to discuss closure of the left atrial appendage with their surgical teams and ask if this is a procedure that can be safely and effectively added to the primary procedure.

Perioperative findings may change the initial plan, "but just like surgical AF ablation at the time of concomitant valve surgery, I think we should start talking about appendage occlusion within our heart team; that way we've got a good approach going into the OR."

The study was funded by grants from Burroughs Welcome, the Food and Drug Administration, and the National Institutes of Health. Friedman reports receiving educational grants from Boston Scientific and St Jude Medical and research grants from the National Cardiovascular Data Registry. Singh reports receiving consultant fees/honoraria from Biotronik, Boston Scientific, Liva Nova, Medtronic, and St Jude Medical; being on the data safety monitoring board for Respicardia; and receiving research grants from Boston Scientific and St Jude Medical. Ellenbogen reports receiving consultant fees/honoraria from the American Heart Association, AtriCure, Biosense Webster, Biotronik, Boston Science, the Heart Rhythm Society, Janssen, Medtronic, Pfizer, Sentra Heart, and St Jude Medical; being on the data safety monitoring board and giving expert witness testimony for Medtronic; and receiving research grants from AtriCure, Daiichi Sankyo, Medtronic, Boston Science, Biosense Webster, and the National Institutes of Health. Fisher reports receiving consultant fees/honoraria from Medtronic and has other ties to Biotronik, Boston Scientific/GDT, Medtronic, and St Jude Medical.

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