Vivek Y. Reddy
BOSTON — While not frequent, thrombosis related to a left atrial occlusion device for stroke prevention was associated with a markedly elevated risk for stroke and systemic embolism, according to findings presented at the Heart Rhythm Society Annual Scientific Sessions.
The rate of device-related thrombosis for patients who underwent LAA occlusion with the Watchman device (Boston Scientific) was 3.74%, but those who had device-related thrombosis were more than three times as likely to have stroke or systemic embolism, Vivek Y. Reddy, MD, director of cardiac arrhythmia services for The Mount Sinai Hospital and the Mount Sinai Health System and the Leona M. and Harry B. Helmsley Charitable Trust Professor of Medicine in Cardiac Electrophysiology at Icahn School of Medicine at Mount Sinai, said during a presentation.
“When you put a device in the body, until it gets endothelialized over, there is a chance for thrombus to form; we were worried about this from the very beginning,” Reddy told Cardiology Today. “In the PROTECT-AF trial, we saw about a 5% thrombus rate, and we saw a slightly higher stroke rate in that population. But that was in small numbers of patients with limited follow-up. Now, we combined patients from the PROTECT-AF and PREVAIL randomized controlled trials and the CAP and CAP2 registries to accumulate a big dataset followed for a long time.”
The researchers analyzed 1,739 patients (mean age, 74 years; 34% women) treated with the device; follow-up included 7,159 patient-years. All patients received surveillance transesophageal echocardiography (TEE) at 45 days and 1 year; those from the randomized trials also received it at 6 months.
The rates of any stroke and symbolic embolism were 7.46 per 100 patient-years in patients with device-related thrombosis and 1.78 per 100 patient-years in those without device-related thrombosis (adjusted rate ratio [RR] = 3.55; 95% CI, 2.18-5.79), while the rates of ischemic stroke and symbolic embolism were 6.28 per 100 patient-years in patients with device-related thrombosis and 1.65 per 100 patient-years in those without it (adjusted RR = 3.22; 95% CI, 1.9-5.45), according to the researchers.
Of all cases of stroke and symbolic embolism, 86.62% occurred in patients without device-related thrombosis.
“Overall, device-related thrombosis is a relatively small contribution” to stroke after LAA occlusion, Reddy said.
Additionally, the following were identified as predictors of device-related thrombosis:
- History of transient ischemic attack or stroke (OR = 2.31; 95% CI, 1.26-4.25);
- Permanent AF (OR = 2.24; 95% CI, 1.19-4.2);
- Vascular disease (OR = 2; 95% CI, 1.08-3.91);
- LAA diameter (OR per 1-mm increase = 1.06, 95% CI 1.01-1.12); and
- Left ventricular ejection fraction (OR per 1% increase = 0.96; 95% CI, 0.94-0.99).
The researchers performed a temporal analysis of 17 patients with device-related thrombus and stroke. “The question was: Did the thrombus break off and cause a stroke, or are these patients likely to develop stroke for other reasons?” Reddy told Cardiology Today. “In about half of these patients, detection of device-related thrombus and onset of stroke occurred within 1 month of each other. So probably both mechanisms are operative.”
Patients with device-related thrombosis should be monitored closely, Reddy told Cardiology Today. “It means putting them on anticoagulation to get rid of it. It probably means more aggressive surveillance on that population,” he said. “It raises the question of whether we should recommend a different TEE surveillance strategy. You don’t want to expose patients without device-related thrombosis to multiple TEEs that aren’t necessary.”
It is not yet known how anticoagulant therapy after implantation may impact risk for device-related thrombosis, Reddy said. He noted that all patients in the four studies received warfarin for 6 weeks after the procedure. “We don’t know how often they were in therapeutic range, and we don’t know if direct oral anticoagulants would make a difference,” he said.
These findings should not discourage the use of the device, Reddy said. Looking ahead, a new generation device (Watchman Flex), which has begun clinical testing, is much smaller and could confer less device-related thrombosis due to smaller size, he said.
“Whatever you thought about the safety and efficacy of the therapy doesn’t change because of this,” Reddy told Cardiology Today. “We identified a population that we should aggressively treat.” – by Erik Swain
Reddy VY, et al. LBCT02-05. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 9-12, 2018; Boston.
Dukkipati SR, et al. Circulation. 2018;doi:10.1161/CIRCULATIONAHA.118.035090.
Disclosure: The studies from which the analysis was derived were funded by Boston Scientific. Reddy reports he consults for and receives grant support from Boston Scientific.