News from… Boston Scientific
WATCHMAN in Practice: WATCHMAN is a self-expanding nickel titanium (nitinol) frame with fixation anchors and a permeable polyester fabric cover. It is designed to be implanted as a permanent mechanism to trap potential emboli before they exit left atrial appendage (LAA). The device is implanted via a transseptal approach by use of a catheter-based delivery system and may be recaptured if necessary. Implantation is performed under either general anaesthesia or conscious sedation with fluoroscopic and transesophageal echocardiography (TEE) guidance. Access to the left atrium is gained via the femoral vein and transseptal puncture.
WATCHMAN in Trials: PROTECT AF is a prospective, randomised, multicentre trial comparing the WATCHMAN device to warfarin for thromboembolic prophylaxis. A total of 707 patients were randomised to the WATCHMAN Device or warfarin (2:1); 93 additional patients rolled-in. More than 90% of patients had successful implantation and LAA closure at six months. Warfarin was discontinued in 87% of patients at 45 days. PROTECT AF demonstrated high rates of success in reducing stroke and mortality. Following the periprocedural period, rates of ischemic stroke with the WATCHMAN device were 1.3 per 100 patient years vs. 1.6 with warfarin. A continued access registry (CAP) implanted an additional 460 patients at 26 centres, which had participated in PROTECT-AF. Procedure time decreased, implantation success increased and procedure-related adverse events decreased. For example, pericardial effusion was reduced from 5% in PROTECT AF to 2.2% in CAP. Procedure-related stroke was reduced from 0.9% in PROTECT AF to 0.0% in CAP.
The Aspirin and Plavix registry (ASAP) was designed to determine if the WATCHMAN device is safe in patients who cannot take warfarin.
A total of 125 patients were enrolled at four European centres. There was a 93% success rate of implantation and a 3.75% rate of stroke compared to an expected rate of 7.37% at one year. PREVAIL is a second randomised study of the WATCHMAN device and is currently underway. Up to 400 patients at 50 sites in the United States will be enrolled.
The primary endpoint is ischemic stroke, hemorrhagic stroke, systemic embolism and cardiovascular/unexplained death.