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Residual peri-device flow not linked to increased risk for thromboembolism
Viles-Gonzalez JF. J Am Coll Cardiol. 2012;59:923-929.
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After percutaneous closure with a left atrial appendage closure device, residual peri-device flow was not associated with an increased risk for thromboembolism vs. standard warfarin therapy.
In the PROTECT AF trial, 485 patients were randomly assigned to implantation of the Watchman left atrial appendage closure device (Atritech) or standard warfarin therapy. After implantation, patients were treated with warfarin for 45 days. Researchers performed transesophageal echocardiography at 45 days, 6 months and 12 months to assess for residual peri-device flow and device stability and positioning. If 45-day transesophageal ECG revealed minimal or no peri-device flow (jet ≤5 mm width), warfarin therapy was discontinued.
The occurrence of stroke, systemic embolism or CV or unexplained death was the composite primary efficacy endpoint.
Of the 485 patients, 445 underwent transesophageal ECG at 45 days. At 12 months, 32% of patients had some degree of peri-device flow. Researchers found an HR of 0.84 (95% CI, 0.62-1.14) in the primary efficacy endpoint per 1 mm larger per-device flow. Compared with patients with no peri-device flow, HRs were 0.85 (95% CI, 0.11-6.40) for minor, 0.83 (95% CI, 0.33-2.09) for moderate and 0.48 (95% CI, 0.11-2.09) for major peri-device flow.
Overall, 13% of patients continued warfarin treatment for some additional period — 64% because of peri-device flow, 22% because of physician order and 14% for other reasons. Compared with patients with no peri-device flow who discontinued warfarin, patients with any device flow continuing warfarin had an HR of 0.63 (95% CI, 0.14-2.71) for the primary efficacy endpoint.
The researchers noted, however, that their results should be interpreted with caution.
“A study with a larger sample size or a study with higher event rates would likely narrow the confidence interval and make the results more definitive,” they wrote. Therefore, our conclusions should be strictly hypothesis generating.”
Disclosure: Some of the study researchers report receiving clinical research grant support or consulting fees from Atritech and Boston Scientific.