To evaluate if ticagrelor, an effective platelet inhibitor without known non-responders, could inhibit growth of small abdominal aortic aneurysms (AAAs).

In this multi-centre randomized controlled trial, double-blinded for ticagrelor and placebo, acetylic salicylic acid naïve patients with AAA and with a maximum aortic diameter 35–49 mm were included. The primary outcome was mean reduction in log-transformed AAA volume growth rate (%) measured with magnetic resonance imaging (MRI) at 12 months compared with baseline. Secondary outcomes include AAA-diameter growth rate and intraluminal thrombus (ILT) volume enlargement rate. A total of 144 patients from eight Swedish centres were randomized (72 in each group). MRI AAA volume increase was 9.1% for the ticagrelor group and 7.5% for the placebo group (P = 0.205) based on intention-to-treat analysis, and 8.5% vs. 7.4% in a per-protocol analysis (P = 0.372). MRI diameter change was 2.5 mm vs. 1.8 mm (P = 0.113), US diameter change 2.3 mm vs. 2.2 mm (P = 0.778), and ILT volume change 12.9% vs. 10.4% (P = 0.590).

In this RCT, platelet inhibition with ticagrelor did not reduce growth of small AAAs. Whether the ILT has an important pathophysiological role for AAA growth cannot be determined based on this study due to the observed lack of thrombus modulating effect of ticagrelor.

The TicAAA trial is registered at the US National Institutes of Health (ClinicalTrials.gov) #NCT02070653.