The largest multicenter randomized trial to date of CT angiography before left atrial appendage closure (LAAC) to treat atrial fibrillation has added to the evidence that the imaging technique on top of transesophageal echocardiography achieves a higher degree of short- and long-term success than TEE alone.
The results are from a subanalysis of the Swiss-Apero trial, a randomized comparative trial of the Watchman and Amulet devices for LAAC, which published results in Circulation.
“Our observational data support to use of CT for LAAC procedure planning,” senior investigator Lorenz Räber, MD, PhD, said in an interview. “This is not very surprising given the high variability of the LAA anatomy and the associated complexity of the procedure.” Dr. Räber is director of the catheterization laboratory at Inselspital, Bern (Switzerland) University Hospital.
The study, published online in JACC: Cardiovascular Interventions, included 219 LAAC procedures in which the operators performed coronary CT angiography (CTTA) beforehand. When the investigators designed the study, LAAC procedures were typically planned using TEE alone, and so participating operators were blinded to preprocedural CCTA imaging. Soon after the study launch, European cardiology societies issued a consensus statement that included CCTA as an option for procedure planning. So the Swiss-Apero investigators changed the subanalysis protocol to unblind the operators – that is, they were permitted to plan LAAC procedures with CCTA imaging in addition to TEE. In this subanalysis, most patients had implantation with blinding to CCTA (57.9% vs. 41.2%).
Study results
The subanalysis determined that operator unblinding to preprocedural CCTA resulted in better success with LAAC, both in the short term, at 93.5% vs. 81.1% (P = .009; adjusted odds ratio, 2.76; 95% confidence interval, 1.05-7.29; P = .40) and the long term, at 83.7% vs. 72.4% (P = .050; aOR, 2.12; 95% CI, 1.03-4.35; P = .041).
Dr. Räber noted that this is only the third study to date that examined the potential impact of preprocedural CCTA plus TEE. One was a small study of 24 consecutive LAAC procedures with the Watchman device that compared TEE alone and CCTA plus TEE, finding better outcomes in the group that had both imaging modalities . A larger, single-center cohort study of 485 LAAC Watchman procedures found that CCTA resulted in faster operation times and higher successful device implantation rates, but no significant difference in procedural complications.
Dr. Räber explained why his group’s subanalysis may have found a clinical benefit with CCTA on top of TEE. “Our study was much larger, as compared to the randomized clinical trial, and there was no selection bias as in the second study mentioned before, as operators did not have the option to decide whether or not to assess the CCTA prior to the procedure,” he said. “Finally, in the previous studies there was no random allocation of device type” – that is, Amulet versus Watchman.
One study limitation Dr. Räber noted was that significantly more patients in the blinded group were discharged with dual-antiplatelet therapy. “The lower rate of procedure complications observed in unblinded procedures was mostly driven by a lower number of major bleedings and in particular of pericardial tamponade,” he said. “We cannot therefore exclude that the higher percentage of patients under dual-antiplatelet therapy in the CCTA-blinded group might have favored this difference.”
However, he noted the investigators corrected their analysis to account for differences between the groups. “Importantly, the numerical excess in major procedural bleeding was observed within both the single-antiplatelet therapy and dual-antiplatelet therapy subgroups of the TEE-only group.”
In an accompanying editorial, coauthors Brian O’Neill, MD, and Dee Dee Wang, MD, both with the Center for Structural Heard Disease at Henry Ford Hospital in Detroit, noted that the Swiss-Apero subanalysis “reinforced” the benefit of CCTA before LAAC.
“This study demonstrated, for the first time, improved short- and long-term procedural success using CT in addition to TEE for left atrial appendage occlusion,” Dr. O’Neill said in an interview. “This particular study may serve as a guide to an adequately powered randomized trial of CT versus TEE in left atrial appendage occlusion.” Future LAAC trials should incorporate preprocedural CCTA.
Dr. O’Neill noted that, as a subanalysis of a randomized trial, the “results are hypothesis generating.” However, he added, “the results are in line with several previous studies of CT versus TEE in left atrial appendage occlusion.”
Dr Räber disclosed financial relationships with Abbott Vascular, Boston Scientific, Biotronik, Infraredx, Heartflow, Sanofi, Regeneron, Amgen, AstraZeneca, CSL Behring, Canon, Occlutech, and Vifor. Dr. O’Neill disclosed financial relationships with Edwards Lifesciences, Medtronic, and Abbott Vascular.