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.
Dr. Jens Erik Nielsen-Kudsk
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.
Dr. 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.
Dr. 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,” Dr. 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.”