, itself an important risk factor for cerebrovascular events, in patients with implants for left atrial appendage occlusion (LAAO), new research suggests.
The identified independent predictors of DRT in the largest dedicated multicenter LAAO-DRT registry to date were presence of a hypercoagulability disorder, pericardial effusion, renal insufficiency, an implantation depth greater than 10 mm from the pulmonary ridge, and presence of nonparoxysmal atrial fibrillation (AFib).
“Unfortunately, most of them are not modifiable, like hypercoaguable disorders or nonparoxysmal atrial fibrillation. But we can avoid deep implants because that’s been associated with creating a little bit of a crater or valley where the clot can form,” senior author Mohamad Alkhouli, MD, said in an interview.
But most important, and “really why we wanted to do this,” he said, is that “we want to give the patient a realistic prediction of adverse events for this procedure.”
LAAO has taken off in recent years for preventing thrombus formation and stroke in patients with AFib. Predicting DRT is a priority for the LAAO field, the authors note, especially given its expansion to younger, lower-risk patients and the increasing procedural volumes.
“This is a problem, DRT, that’s been discussed a lot because this is a preventative procedure,” observed Dr. Alkhouli, professor of medicine at Mayo Medical School, Rochester, Minn.
“The actual stroke risk every year – even if you don’t take any blood thinner and you have a CHADsVASc score of 9, the highest – is 11%. So if the chance of having thrombus is close, then that’s not a good tradeoff.”
Previous studies have also identified implantation depth and nonparoxysmal AFib as risk factors for DRT. But most of them have been small, he noted, with one of the largest reporting 65 DRTs in four prospective trials.
To cast a wider net, the investigators, led by Trevor Simard, MD, also from the Mayo Clinic, invited more than 50 international sites to contribute data to the registry. Of these, 37 centers reported on 237 DRTs and 474 device-matched control subjects from the same site.
Three-fourths of patients received a first-generation Watchman or a FLEX device (Boston Scientific).
Medical regimens were similar between the DRT and control cohorts at discharge after LAA closure. Most patients were managed with single (36.3%) or dual antiplatelet therapy (26.2%) at the time of DRT diagnosis.
As reported July 19 in the Journal of the American College of Cardiology, the timing of DRT development varied widely, with 24.9% appearing in the first 45 days, 38.8% between days 45 and 180, 16.0% between days 180 to 365, and 20.3% beyond 1 year. At last known follow-up, one-quarter of patients had DRT.
The odds ratios for DRT associated with the five identified risk factors were:
- 17.50 (95% confidence interval, 3.39-90.45) for hypercoagulability disorder
- 13.45 (95% CI, 1.46-123.52) for pericardial effusion
- 4.02 (95% CI, 1.22-13.25) for renal insufficiency
- 2.41 (95% CI, 1.57-3.69) for implantation depth >10 mm
- 1.90 (95% CI, 1.22-2.97) for nonparoxysmal AFib