Examining data from each procedure, the authors determined that 56% of patients belonged in the proximal implant group and the remaining 44% belonged in the distal implantation group. Patients with permanent nonvalvular AFib and/or chronic heart failure were more likely to be in the distal implantation group than the proximal implantation group. These patients were also more likely to be prescribed direct oral anticoagulants.

Procedural outcomes were not significantly different between the two groups. The combined rate of procedural major adverse events was 5.3% and there were a total of four patient deaths. After a median follow-up period of 21 months, the overall ischemic stroke and major bleeding event rates were comparable between the two groups. All-cause mortality and cardiovascular mortality were also similar.

The primary focus of the team’s study, DRTs, were seen in 2.3% of proximal implantation patients and 12.2% of distal implantation patients. The research team identified a “stepwise increase in DRT incidence” as implantation depths increased.

“Of note, when the LAAO device was implanted more than 15 mm from the PR, DRT rates of 21.6% and 18.6% were observed with the single-lobe and disc and lobe devices, respectively, compared with 1.5% and 2.5% in the proximal implantation group,” the authors wrote.

With single-lobe devices, the rise in DRT risk was primarily seen beyond a depth of 5 mm. For the disc and lobe devices, however, the increase “became progressive beyond the first distal millimeters.”

Eighty-two percent of DRTs were detected within 180 days of the LAAO procedure.

Running a series of analyses, the team determined that distal implantation and nonantithrombotic or single antiplatelet therapy after LAAO were independent predictors of the patient experiencing a DRT. LAAO device type and peridevice leak were not found to be independent predictors of DRT.

“To date, this is the first study to specifically evaluate the role of LAAO device implantation depth on DRT occurrence,” the authors concluded. “Our results showed that LAAO device implantation depth affects DRT rates, with a higher incidence with deeper implantation and larger uncovered areas. Given its clinical impact, proximal device implantation should be the optimal target in patients undergoing LAAO.”

Read the full study here.