A gut microbiome-derived metabolite called TMAO (trimethylamine N-oxide) may help predict which patients with abdominal aortic aneurysms (AAA) will experience rapid growth and need surgery. Researchers measured blood TMAO in 895 patients across two independent cohorts — one in Sweden, one in the US — and tracked aneurysm size over time. Patients with elevated TMAO (≥6.2 µM) were roughly 2.3 to 2.75 times more likely to have fast-growing aneurysms and about 2.4 to 2.7 times more likely to be recommended for surgical repair. These findings were consistent across both cohorts and held up after adjusting for traditional cardiovascular risk factors, suggesting TMAO could become a clinically useful blood test to guide AAA surveillance and intervention timing.
