Routine 'Preemptive' LAA Closure at Heart Surgery: LAACS Offers More Support

September 06, 2017

BARCELONA, SPAIN — Routine "preemptive" ligation of the left atrial appendage (LAA) during conventional CABG or valve surgery seemed to protect against ischemic strokes, whether silent or clinical, for 3 years or more in a small, single-center randomized trial[1].

The practice, which removes the most common source of embolic thrombi associated with nonvalvular atrial fibrillation (AF), may have cut the risk of stroke or transient ischemic attack (TIA) by 70% regardless of baseline CHA2DS2-VASc score or history of the arrhythmia.

Excision or closure of the LAA is routine at some centers for all patients getting standard "open-heart" surgeries, or it's done selectively or not at all, while the guidelines offer qualified support limited to patients with AF going into the procedure.

The Left Atrial Appendage Closure During Open Heart Surgery (LAACS) study is the first reported randomized trial of the strategy and found that "most patients undergoing open-heart surgery" might benefit from it, Dr Jesper Park-Hansen (Bispebjerg/Frederiksberg University Hospital, Copenhagen, Denmark) told | Medscape Cardiology.

The optimal method of LAA exclusion is more debatable. "The challenge now, and what we will be discussing with our surgeons, is to agree on a feasible, safe, and effective way of left atrial appendage closure." Park-Hansen said ligation with silk suture was the method recommended to operators in LAACS, but LAA exclusion can also be achieved by stapling, surgical excision, or other means.

His view is that "closure with the Lariat [SentreHEART] device could be the way to go, or using some [other] easily reproducible method," said Park-Hansen, who presented LAACS here at the European Society of Cardiology (ESC) 2017 Congress.

Current Practice Based on Scant Evidence

Prior observational studies have concluded variously on the safety and effectiveness of such intra-operative LAA closure or excision as a means to prevent thromboembolism. For example, an analysis from the STS Registry recently saw that adding LAA closure to other heart surgery seemed to reduce thromboembolic risk and mortality over 1 year. But in the separate experience of a major heart center, it seemed to increase the risk of early postoperative AF without any clinical gains in a follow-up exceeding 10 years.

AF is a well-recognized risk early after cardiac surgery that has resisted efforts at pharmacologic prevention, but most of the strokes in the LAACS control group were seen later than 1 year after surgery.

Park-Hansen and others commenting on the study here recognized that the procedure, performed routinely in such surgeries, would need much more definitive support before it could be recommended.

Whether LAA exclusion is performed routinely, even in patients without AF or risk factors, "depends on the surgeon," according to Prof Kurt Huber (Medical University of Vienna, Austria). "I personally wouldn't recommend it before we get more information from prospective randomized trials," he said when interviewed.

"This is only one trial that showed it seems to be safe," said Huber, who is not connected to LAACS. "It's just a single center and a few hundred patients. We need several hundred or a thousand patients in different centers, in different countries."

On the other hand, it could be useful in selected cases, "especially in patients where the risk of developing atrial fibrillation is high," Huber said. "This might be elderly patients and patients who have a history of palpitations but [for whom] nobody could prove that it was atrial fibrillation."

But not every surgeon wants to routinely add the associated risk of bleeding complications. "At the moment, I would concentrate this method in patients with an increased risk of atrial fibrillation or patients you know have atrial fibrillation, are on anticoagulants, and then they need another surgical procedure," he said.

"I'm pretty sure that LAACS, even if there's a signal for less stroke in the long run, would not affect the current recommendations that we have in the guidelines for closure of the left atrial appendage. It is certainly an important piece of the puzzle, but the picture is not yet complete," according to Dr Volkmar Falk (Deutschen Herzzentrums Berlin, Germany).

As formal discussant following Park-Hansen's formal presentation of the trial, Falk agreed that a larger, more definitive trial is needed before any changes to the guidelines.

Serial MR Scans

LAACs enrolled 205 patients referred for CABG, valve surgery, or both to undergo or not undergo surgical LAA closure at the same session; 187 were actually randomized, 101 to LAA closure and 86 as controls.

The two groups were similar at baseline with respect to CHA2DS2-VASc score, history of stroke or AF, important comorbidities, cardiovascular drug treatments, and whether they received isolated CABG or valve surgery vs combined surgeries.

The protocol called for baseline brain MR imaging and repeat scans within 2 to 4 weeks after surgery and at late follow-up, interpreted by radiologists blind to randomization, according to Park-Hansen. Strokes and TIAs were clinically diagnosed by neurologists.

Overall, 19 patients reached the trial's primary end point—first stroke, TIA, or silent cerebral infarction seen clinically or by MR—over a follow-up averaging 3.65 years and ranging up to 6 years. The rates were 5% in the LAA-closure group and 16.3% among controls, for an adjusted hazard ratio (HR) of 0.3 (95% CI 0.1–0.8, P=0.0197) by intention to treat.

Prevalence of Events in LAACS by Both Intention to Treat and Per Protocol

End points by analysis No LAA closure (n) LAA Closure (n) P
Randomized (patients) 86 101  
Primary EP* 14 5 0.02
Stroke 8 3 0.07
Per protocol (patients) 77 64  
Primary EP* 14 4 0.04
Stroke 8 2 0.09
*First stroke, TIA, or silent cerebral infarction

As surgeons could decide (when technically justified) not to close the LAA in patients with that assignment, a per-protocol analysis was also conducted on 141 patients. The results were marginally significant with 6.3% in the LAA-closure group and 18.2% controls reaching the primary end point, for an adjusted HR of 0.3 (95% CI 0.1–1.0, P=0.0465).

There was no statistical interaction between outcomes and oral anticoagulant use, whether there was AF at baseline, or baseline stroke risk by CHA2DS2-VASc score.

In his critique of the study, Falk cited a range of limitations that could confound interpretation of LAACS, including its limited population that probably made it "severely underpowered," a low rate of enrollment among candidates screened and a low rate of treatment per protocol, and no information on how often cardiopulmonary bypass support was used during surgery.

Both he and Huber questioned the method of LAA closure used in the study, suturing, as being associated with a notable risk of bleeding complications and need for repeat surgery.

Also, said Falk, "Endocardial suturing in some studies leaves a remnant LAA in up to 50% and complete reperfusion in 25% [of cases]. Pretty much the only method that provides 100% closure of the LAA is clipping, which is probably the best method of choice in this context."

Underscoring the lack of agreement in the field about whether to routinely close the LAA at surgery and if so, by what method, Park-Hansen had singled out clipping and stapling as less preferable than suturing due to a greater risk of bleeding complications.

The study had no commercial sponsors. Park-Hansen, Falk, and Huber report they have no relevant financial relationships.

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