LAA Thrombus Explored as Potential Cause of Stroke After TAVR

Left atrial appendage (LAA) thrombus is commonly detected in patients being considered for TAVR and dislodgement of the clot possibly represents an additional mechanism for periprocedural stroke, which remains a dreaded—though reportedly declining—complication of the procedure.

Those are the key conclusions from research showing a rate of in-hospital stroke of 20% in patients with definite LAA thrombus and 3.8% in those without a clot. With just six events total (two in the former group and four in the latter), however, definitive conclusions about the clinical impact of LAA thrombus in this population cannot be made, lead author Sonny Palmer, MBBS, DMedSci (St. Vincent’s Hospital Melbourne, Australia), and colleagues report.

Nevertheless, “this finding does raise the possibility that LAA thrombus embolization may represent a clinically important cause of procedural stroke,” they write in a study published in the January 23, 2017, issue of JACC: Cardiovascular Interventions. “Given this potential risk, we recommend that investigation for LAA thrombus should be performed in all patients planned for TAVR.”

LAA Thrombus Relatively Common

As previously reported by TCTMD, just after the current study was presented at EuroPCR 2016, the discovery of a thrombus in the LAA during a pre-TAVR evaluation poses a clinical quandary for physicians performing TAVR, given the lack of data or guidance in this area.

Patients undergoing TAVR frequently have A-fib. A major mechanism for the elevated risk of stroke associated with the arrhythmia is embolization of LAA thrombus. The potential impact of dislodged LAA thrombus on periprocedural stroke risk in TAVR patients, however, has not been well studied.

For the current study, Palmer et al examined dual-phase cardiac CT scans for LAA thrombus in 198 patients being considered for TAVR; 35% had A-fib.

Overall, 11% of patients had definite LAA thrombus, with a higher rate seen in patients with A-fib (32%). Only two patients had LAA thrombus without a history of A-fib.

Cardiac CT performed well for detection of LAA thrombus when compared with transesophageal echocardiography (TEE) in patients who were screened with both modalities. It had a sensitivity of 100%, specificity of 98%, and negative predictive value of 100%.

The authors point out that cardiac CT has become a routine part of the pre-TAVR work-up at many centers, and because it can also be used to check the LAA, “it may obviate the need for preprocedural TEE.”

In the patients who ultimately underwent TAVR—with either the Sapien XT or Sapien 3 valve (Edwards Lifesciences)—the in-hospital stroke rate was 4.8%. Two of the six patients with stroke had definite LAA thrombus. Both had A-fib and were receiving warfarin at the time of cardiac CT; anticoagulation was stopped 5 days before TAVR in both cases. The remaining four patients with stroke did not have A-fib or LAA thrombus.

You Found Thrombus, Now What?

The authors point out that 80% of the patients with LAA thrombus were already receiving anticoagulation. Moreover, anticoagulation may be contraindicated in some patients, highlighting the need to develop approaches for managing patients with thrombus.

When a clot is found, Palmer et al write, “we postpone TAVR and review the patient’s anticoagulation regimen and medication compliance.” Warfarin-treated patients may be treated to a higher INR goal or use of a non-vitamin K antagonist oral anticoagulant may be considered, they add. They repeat imaging 3 or 4 weeks later to see if the thrombus has dissolved.

If the clot remains, a decision must be made about whether to perform TAVR anyway.

“Given the impressive symptomatic and prognostic gains from TAVR, we believe that this therapy should not be withheld, but patients with LAA thrombus should be informed that there may be an increased risk for stroke,” the authors say. They add that consideration should be given to using strategies to reduce the risk of embolization in such cases. That might include periprocedural bridging with low-molecular-weight heparin, use of cerebral embolic protection devices, or taking measures to minimize use of rapid pacing. 

In an accompanying editorial, Samir Kapadia, MD (Cleveland Clinic, OH), and colleagues say the study raised interesting questions about how periprocedural management might be changed in higher-risk patients, including those with LAA thrombus.

They mention bridging and protection devices as well as the avoidance of protamine, which is used to reverse procedural anticoagulation. Also, optimal antithrombotic management after TAVR is an area of active investigation, they note.

“A systematic approach to investigate different strategies for stroke prevention, including procedural modifications like [transcatheter embolic protection], diagnosis and prevention of [A-fib]-related strokes, and postprocedural pharmacotherapy will help to further improve outcomes of patients undergoing TAVR,” they write.