ASAP Published: Watchman a Safe Option for A-fib Patients Ineligible for Warfarin

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Percutaneous closure of the left atrial appendage (LAA) with the Watchman device can be safely performed without a warfarin transition, and is a reasonable alternative for patients with atrial fibrillation (A-fib) at high risk for stroke but contraindicated for oral anticoagulation, according to a study scheduled to be published online April 9, 2013, in the Journal of the American College of Cardiology.

For the ASAP study, Vivek Y. Reddy, MD, of Mount Sinai School of Medicine (New York, NY), and colleagues prospectively enrolled 150 patients with nonvalvular A-fib and a CHADS2 score of at least 1who were ineligible for oral anticoagulation. Patients underwent LAA closure with the Watchman device (Boston Scientific, Natick, MA) at 4 centers between January 2009 and November 2011.

The results of the ASAP trial were previously presented in November 2012 at the Transcatheter Cardiovascular Therapeutics scientific symposium in Miami Beach, FL.

Watchman Without Warfarin Safe, Effective

After follow-up of 14.4 ± 8.6 months, the combined primary efficacy endpoint (ischemic stroke, hemorrhagic stroke, systemic embolism, and cardiovascular/unexplained death) occurred in 8 patients, a rate of 4.6 events per 100 patient-years. Stroke was seen in 4 patients, a rate of 2.3 events per 100 patient-years. In addition, 9 patients died, 3 of cardiovascular causes.

Because the mean CHADS2 score for the overall population was 2.8 ± 1.2 and 85% of patients had a CHADS2 score of at least 2, the researchers estimated an expected annual ischemic stroke rate of 7.3%. However, the observed rate was only 1.7%, which represents 77% fewer events than was expected.

Serious procedure- or device-related safety events occurred in 8.7% of patients (n = 13) and included device embolization without sequelae (n = 2), pericardial effusion with (n = 2) or without (n = 3) tamponade, and device thrombus with ischemic stroke (n = 1).

In addition, 6 cases of device-related thrombus were seen during follow-up, but only 1 was associated with stroke and deemed a serious adverse event after adjudication.

‘Greater Flexibility’ for Watchman Use

The study was the first to test closure with the Watchman device in patients ineligible for oral anticoagulation, according to Dr. Reddy, and hence “we didn’t know if it was safe to put the device in [these patients],” he said in a telephone interview with TCTMD. “We showed that it was safe with just aspirin and [clopidogrel as] transition. So that allows us greater flexibility in terms of patient population.”

In a telephone interview with TCTMD, Ziyad M. Hijazi, MD, MPH, of Rush University Medical Center (Chicago, IL), said ASAP “confirms the idea that [we can] make life easier for our patients because [warfarin] has a lot of complications. At the end of the day, [the risk that comes with warfarin is] not worth it. The [Watchman] procedure is very safe, very good, and a lot of the complications and adverse events that were initially encountered will be avoided with experience.”

He said he was unsurprised by the efficacy of LAA closure because “basically 90% of the source of the clot is the appendage, and if you close the appendage then you should basically avoid all these ischemic stroke complications.”

The study provides “significant new information,” said Robert J. Sommer, MD, of Columbia University Medical Center (New York, NY). He told TCTMD in a telephone interview that “[there was a] notion that there was going to be something much more thrombogenic about these devices at 45 days, [but] I don’t know that we have any data on that.”

Recently presented data from both the PREVAIL and PROTECT AF trials “[gives us] a really good handle on the idea that at a minimum this technology is noninferior to warfarin, and if we ultimately go for a long enough period of time, it may turn out to be superior,” he said, adding that he expects the US Food and Drug Administration to approve the Watchman device later this year.

What About Antiplatelet Therapy?

Dr. Hijazi said he would like to see a randomized trial of the Watchman device in patients ineligible for warfarin therapy. However, “[warfarin] is probably going to be replaced by one of the new factor Xa inhibitors,” he said, so a trial should “compare closure of the appendage with the device alone versus device closure of the appendage plus anticoagulation.”

Looking to the future, Dr. Reddy said “it’s nice that we can [implant a Watchman in patients ineligible for warfarin], but it would be even nicer if we didn’t have to give 6 months of [clopidogrel].” Because the bleeding risk associated with antiplatelet therapy is “not trivial,” it would be beneficial if “maybe we can get away with 1 or 3 months of [clopidogrel],” he said.

Dr. Reddy noted that patients in the ASAP trial will continue to be followed for up to 3 years. “We expect the data to look the same,” he observed. “All the other studies that we’ve looked at with longer-term follow-up haven’t [shown] any surprises, but again you’d like to see that happen.”

Study Details

The mean age of patients was 72.5 ± 7.4 years, and 64% were male. The most common risk factor for stroke was hypertension (94.7%), and 40% of patients previously experienced an ischemic stroke/TIA. History of hemorrhagic/bleeding tendencies (93%) was the most common reason for warfarin ineligibility


Reddy VY, Mӧbius-Winkler S, Miller MA, et al. Left atrial appendage closure with the Watchman device in patients with a contraindication for oral anticoagulation: ASA Plavix feasibility study with Watchman left atrial appendage closure technology (ASAP study). J Am Coll Cardiol. 2013;Epub ahead of print.



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  • ASAP was supported by Boston Scientific.
  • Dr. Reddy reports receiving grant support and/or consulting fees from Boston Scientific.
  • Dr. Hijazi reports no relevant conflicts of interest.
  • Dr. Sommer reports serving as the PI for both the PREVAIL trial and the CAP2 registry.