Investigation of serum trimethylamine N-oxide levels in ischemic cerebrovascular diseases

Stroke remains a leading cause of mortality and disability worldwide and in Turkey. Recent studies indicate that the gut microbiota and its metabolite, trimethylamine N-oxide (TMAO), play a significant role in the pathogenesis of cerebrovascular diseases through mechanisms such as atherosclerosis and thrombosis. This study aimed to investigate the relationship between serum TMAO levels and the causes, types, comorbidities, prognosis, and treatment methods applied in ischemic cerebrovascular diseases. The study included 228 patients with ischemic stroke and 37 healthy volunteers who presented to the neurology clinics of Selçuk University Faculty of Medicine and Konya City Hospital between May 10, 2023, and April 30, 2024. Serum TMAO levels were measured at admission and on day 7, and these values were compared with the patients' clinical (NIHSS, MRS), laboratory, and radiological (infarct volume, ASPECTS) findings. Admission TMAO levels were significantly higher in patients with hypertension compared to those without. Higher baseline TMAO levels were positively correlated with stroke severity (NIHSS), functional dependency (MRS), and infarct volume. In the minor, major, and endovascularly treated stroke groups, TMAO levels significantly decreased by day 7, while they increased in the transient ischemic attack (TIA) and carotid stent groups. The magnitude of the decrease in TMAO ("TMAO change") between admission and day 7 was associated with larger infarct volumes and worse clinical outcomes. Conversely, higher TMAO levels on day 7 were associated with better functional outcomes (lower MRS) at 3 months. This study demonstrates that TMAO is a dynamic prognostic biomarker rather than a static risk factor in ischemic cerebrovascular events. The change in TMAO levels between admission and day 7 may be a valuable tool in predicting the patient's clinical prognosis. A significant drop in TMAO levels during the acute phase may indicate a poor prognosis, while higher levels in the subacute phase might be associated with a potential protective mechanism. Keywords: TMAO; stroke; endovascular therapy; IV tPA; stent.