Left Atrial Appendage Occlusion, DOAC Comparable for AFib

Richard Mark Kirkner

January 14, 2021

Left atrial appendage occlusion (LAAO) for high-risk atrial fibrillation seems to prevent stroke as well as direct oral anticoagulation (DOAC) with a lower risk of major bleeding, according to results of a European study.

And although some experts question the strength of the conclusions, a lead researcher contends the study may provide enough support for interventional cardiologists to consider LAAO in selected patients until randomized clinical trials yield stronger evidence.

"The results suggest LAAO to be superior to DOAC in AF patients who have a predicted high risk of stroke and bleeding and adds to the evidence that LAAO is a promising stroke prevention strategy in selected AF patients," said lead investigator Jens Erik Nielsen-Kudsk, MD, DMSc, a cardiologist at Aarhus University Hospital in Denmark.

Nielsen-Kudsk and colleagues wrote in JACC: Cardiovascular Interventions that this is the largest comparative study of LAAO vs. DOAC to date, but they also acknowledged the study limitations: its observational design, unaccounted confounders, potential selection bias, and disparities in the nature of the comparative datasets (a multination cohort vs. a single national registry).

Observational Registry Study Shows 43% Reduction in Primary Outcome

The study compared outcomes of 1,078 patients from the Amulet Observational Study who had LAAO during June 2015–September 2016 with 1,184 patients on DOAC therapy selected by propensity score matching from two Danish national registries. The LAAO population was prospectively enrolled at 61 centers in 17 countries. The study population had a high risk of stroke and bleeding; about one-third had a previous stroke and about three-quarters had a prior bleeding episode. The average age was 75 years.

The LAAO group had almost half the rate of the primary outcome — either stroke, major bleeding, or all-cause death — 256 vs. 461 events in the DOAC group with median follow-up of 2 years. The annualized event rate was significantly lower for the LAAO group: 14.5 vs. 25.7 per 100 patient years in the DOAC group. The researchers calculated the LAAO group had a relative 43% reduction risk.

Of the LAAO group, 155 patients (14.5%) died in the follow-up period, 35% of them from a cardiovascular cause, whereas 308 (26%) of patients in the DOAC group died, with a similar percentage, 36%, from a cardiovascular cause.

Using data from the Danish Cause of Death Registry, the study determined cause of death in the DOAC patients on a more granular level: 9.5% of the deaths were from vascular disease and 4.5% from stroke (the remainder in both groups were from noncardiovascular events).

Stroke incidence was similar between the two groups: 39 in the LAAO group vs. 37 in DOAC patients, conferring an 11% greater risk in the former. The risk of major bleeding and all-cause mortality were significantly lower in LAAO patients, 37% and 47%, respectively. However, 50% of DOAC patients had discontinued therapy after a year of follow-up, and 58% had done so after 2 years.

Nielsen-Kudsk noted that the findings line up with those from the smaller PRAQUE-17 study comparing LAAO and DOAC. He added that his group is participating in two larger RCTs, CATALYST and CHAMPION-AF, evaluating LAAO and medical therapy in about 6,000 patients combined.

"It will take at least 2 to 5 years before we have data from these randomized LAAO trials," Nielsen-Kudsk said. "Meanwhile, based on data from three prior randomized clinical trials, propensity-score matched studies and data from large registries, LAAO should be considered in clinical practice for patients who have a high risk of bleeding or who for any other reason are unsuitable for long-term DOAC treatment."

Noncompliance to DOAC Therapy a Concern

In an invited commentary, Mohamad Alkhouli, MD, of the Mayo Medical School, Rochester, Minn., wrote, "These findings provide reassuring evidence supporting the efficacy of LAAO despite the remaining challenges with this therapy."

However, Alkhouli pointed out that the high rate of noncompliance among AF patients on DOAC can be a confounding factor for interpreting the efficacy of therapy. "This highlights the challenges of comparing LAAO to DOAC, considering that many patients are actually not on effective anticoagulation, but also suggests a possible real important role for LAAO in addressing the unmet need in stroke prevention in nonvalvular atrial fibrillation," he said in an interview.

"The study showed a very good safety profile for LAAO," Alkhouli added. "However, we should remember that this was an observational study without routine temporal imaging and a relatively short-term follow- up."

Methods 'Severely Flawed'

John Mandrola, MD, an electrophysiologist at Baptist Health in Louisville, Ky., said the study methodology was "severely flawed," citing its nonrandomized nature and enrollment of only patients with successful implants in the LAAO group. "You have to take all patients who had attempted implants," he said. Further, the study may be subject to selection bias based on how patients were recruited for the Ampulet Observational Study.

"Comparing LAAO to DOAC is a vital clinical question," said Mandrola. "It simply cannot be answered with observational methods like this. It requires a properly powered RCT."

Alkhouli said he's looking forward to results from five large RCTS evaluating LAAO due in 3–5 years. "Until the results of those trials are out, careful patient selection and shared decision-making should continue to govern the rational dissipation of LAAO as a stroke prevention strategy," he said.

Novo Nordisk Research Foundation supported the study and Abbott provided a grant. Nielsen-Kudsk disclosed financial relationships with Abbott and Boston Scientific. Coauthors disclosed relationships with Abbott, Boston Scientific, Bayer Vital, Bristol Myers Squibb, Boehringer Ingelheim, Daiichi-Sankyo, Medtronic, Pfizer, Portolo, and Sanofi.

Alkhouli disclosed a relationship with Boston Scientific. Mandrola has no relevant disclosures. He is chief cardiology correspondent for Medscape.com. MDedge is a member of the Medscape Professional Network.

This article originally appeared on MDEdge.com.

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