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Electrical cardioversion without routine extra anticoagulation around the procedure may be feasible for people who've already received left atrial appendage (LAA) occlusion, according to a small retrospective study.

Patients with a Watchman implant who received direct current cardioversion for atrial fibrillation (Afib) did not experience any thromboembolic complications from the procedure, reported Dhanunjaya Lakkireddy, MD, of the Kansas City Heart Rhythm Institute, and colleagues.

Three transient ischemic attacks were reported but deemed unrelated to electrical cardioversion, having occurred more than 3 months after the shock. Moreover, there was no device or left atrial thrombosis, device dislodgement, or new device leak over follow-up of a median 12.8 months

The only death was due to a non-cardiac cause, the researchers noted in the Nov. 5 issue of the .

The 22% of patients who started oral anticoagulation after cardioversion had no more procedural complications than peers who didn't, although numerically more bleeding events (6% vs 1.5%, P=0.20).

Cardioverting high-risk Afib patients after they already received Watchman LAA occlusion is therefore feasible in the absence of anticoagulation -- provided that pre-procedural transesophageal echocardiography (TEE) shows good device position, absence of device-related thrombus, and peridevice leaks smaller than 5 mm, Lakkireddy's team concluded.

"The preliminary results are encouraging, but further large studies are warranted to establish safety," the investigators cautioned.

The study included 148 consecutive Afib patients at several hospitals. Average age was 72 years; men made up 59% of the group. The cohort was roughly split between paroxysmal Afib and persistent or long-standing persistent Afib.

"Given the low rate of events after DCCV [direct current cardioversion], the lack of events in a series of 148 patients could be due to chance. If just two post-procedure events occurred in the next 50 patients, the rate would be more than double the established safety threshold," a group led by John Mandrola, MD, of Baptist Health Louisville in Kentucky, noted in their .

At the time of cardioversion in 2013-2017, some patients were already on oral anticoagulation (34%), some on dual antiplatelet therapy with aspirin and clopidogrel (Plavix; 30%), and the remainder on aspirin alone (36%).

"Thus, a procedure whose main benefit is supposed to be removal of anticoagulation resulted in 58% of patients on OAC [oral anticoagulation]," a group led by John Mandrola, MD, of Baptist Health Louisville in Kentucky, estimated in their .

"The need for an extra procedure and a high chance of remaining on potent antithrombotic drugs would surely be of interest to patients who are amenable to future rhythm control approaches and counseled to have LAA occlusion," the editorialists said.

"We urge caution, not only for doing DCCV after LAA closure, but also for embracing nonpharmacological stroke prevention with LAA occlusion in the first place. This paper should prompt us to stop and think about this technology," the editorialists emphasized.

After all, they said, the had left Watchman patients with significantly higher bleeding and complication rates. The subsequent FDA-mandated PREVAIL trial failed to show non-inferiority for the Watchman in the first coprimary endpoint, and barely met noninferiority in its second coprimary endpoint of stroke and systemic embolism excluding events 7 days after the procedure

Now there is a concerning possibility of "indication creep" as the Watchman is supposed to be used in those who can't tolerate long-term anticoagulation.

In the study by Lakkireddy's team, 61% of participants had not experienced a gastrointestinal bleed. Additionally, the mean HAS-BLED score was only 3, indicating bleeding risk that was not high enough to warrant discontinuation of oral anticoagulation, Mandrola and colleagues pointed out.

From a pre-procedural TEE, operators found that 2.7% of the group had a device-related thrombus. This subgroup of patients had the clot resolve over several weeks of direct oral anticoagulation before another attempt at cardioversion.

Cardioversion restored sinus rhythm to all patients. Just over half of these electric shocks were given from 6 weeks to 1 year post-LAA occlusion. People who received a new oral anticoagulant afterward were found to have undergone cardioversion sooner after Watchman implantation (3.6 vs 8.6 months, P=0.003).

The study's retrospective nature meant selection bias was a possibility. There was no control group, either, and the LAA closure experience was limited to the Watchman device, acknowledged Lakkireddy and colleagues.