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Clinical Articles, Lead Article

News from ACC.13 – more on drugs and devices

The PREVAIL trial of a new device which closes the left atrial appendage in the heart (Watchman®, Boston Scientific) attracted huge controversy at the American College of Cardiology (ACC) Scientific Session 2013, held recently in San Francisco, when it was removed from the programme within an hour of its presentation because of an embargo break by the sponsor, Boston Scientific.

But the slides and a press release were still made available to the media, and preliminary results appear to suggest some reassurance on safety concerns generated in a previous study.

The device, which is implanted via a trans-septal catheter-based delivery system, is already available in Europe for the prevention of stroke in atrial fibrillation (AF) patients, but it has not been approved by the USA Food and Drug Administration (FDA) because of safety concerns raised in the previous PROTECT-AF trial. These related to a high initial rate of pericardial effusions and procedure-related strokes. The PREVAIL trial was therefore conducted to give more information on safety and to confirm the efficacy results shown in PROTECT-AF.

800px-Golden_gate_bridge_in_San_FranciscoThe PREVAIL trial enrolled 407 patients who were randomised 2:1 to the device or warfarin. Device patients were given 45 days of warfarin therapy. The study had a Bayesian design, which means that the PROTECT results were also taken into account when assessing efficacy. Results showed that the device had a 95.1% implant success rate, up from the 91% rate in PROTECT.

The trial had three co-primary end points, one for safety and two for efficacy. The safety end point was met, as was one of the efficacy end points; the other efficacy end point was narrowly missed. The efficacy results are, however, very preliminary, with only 58 device patients and 30 controls having reached the 18 month follow-up time.

The main safety end point – acute (seven-day) occurrence of death, ischaemic stroke, systemic embolism and procedure, or device-related complications requiring major cardiovascular or endovascular intervention – occurred in six out of 269 patients (2.2%) who received the device. A second, broader, safety end point, including cardiac perforation, pericardial effusion with tamponade, ischaemic stroke, device embolisation, and other vascular complications, occurred in 4.4% of patients receiving the device in PREVAIL, compared with 8.7% in PROTECT.

Cardiac perforation requiring surgical repair occurred in 0.4% of PREVAIL patients receiving the device compared with 1.6% in PROTECT-AF. Pericardial effusion with cardiac tamponade requiring pericardiocentesis occurred in 1.5% of Watchman patients in PREVAIL vs. 2.4% of those in PROTECT AF.

Speaking to the media, lead investigator Dr David Holmes (Mayo Clinic, Minnesota, USA) said: “Despite inclusion of higher-risk patients in PREVAIL than in PROTECT, there were fewer complications, and results show the device can be safely implanted by new operators. The Watchman device therefore offers an alternative to oral anticoagulation therapy for thromboembolic prevention in patients with nonvalvular AF”.

Independent commentator, Dr Gordon Tomaselli (Johns Hopkins University, Baltimore, USA), said he was reassured by the safety data in PREVAIL, and said he would use the device in patients at high risk of stroke who can’t take anticoagulant drugs because of bleeding issues. He added that there were not enough data yet to recommend its use in patients who could take anticoagulants.

Rivaroxaban’s low risk of short treatment interruptions

PREVAIL - ACC table

Table 1. Clinical outcomes in patients with short treatment interruptions

Atrial fibrillation patients who stop taking rivaroxaban for a few days had a low risk of strokes or thrombotic events similar to that seen with similar interruptions of warfarin treatment, according to new results (see table 1) from the ROCKET-AF trial presented at the meeting.

In the analysis, a temporary interruption was defined as three days or more. Of the 14,236 patients in the study, 2,165 receiving rivaroxaban and 2,528 of those on warfarin stopped treatment at some point during the trial for an average duration of five days. The at-risk period was defined as three days after the drug was stopped until three days after the drug was restarted.

More highlights from ACC.13 are available at http://bjcardio.co.uk/2013/04/news-from-the-american-college-of-cardiology-scientific-session-2013/

Published on: April 26, 2013

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