LAACS-2
Left Atrial Appendage Closure by Surgery-2 (LAACS-2)
In 1,500 adults undergoing open-heart surgery, concomitant surgical left atrial appendage closure did not reduce stroke or TIA over 2 years compared with leaving the appendage open.
Closing the appendage in everyone opened on the table costs a few minutes and, in a cohort where only 4% had atrial fibrillation at baseline, prevented nothing measurable over four years — 4.28% against 5.04%, an interval running from a halving to a 37% increase. That is the honest headline, and it separates this trial from LAAOS III, where every patient had atrial fibrillation and closure did work. The subgroup above the median CHA2DS2-VASc score is where the events were and where the effect appeared, which is arithmetically unsurprising and prespecified only as a subgroup: it should decide the next trial's entry criteria, not today's operating list.