Trimethyllysine as a potential biomarker for heart failure.

Trimethyllysine (TML), a methylated amino acid involved in carnitine biosynthesis, has been linked to cardiovascular disease. This cross-sectional study assessed the association between plasma TML and heart failure (HF), and its potential as a diagnostic biomarker. We enrolled 104 participants (65 stable HF patients and 39 non-HF controls) and quantified plasma TML using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results showed that plasma TML levels were significantly higher in the HF group and correlated with various clinical parameters: positively with alanine aminotransferase (ALT), blood urea nitrogen (BUN), serum creatinine (SCr), uric acid (UA), and left ventricular end-diastolic diameter (LVEDD), and negatively with total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDLC), estimated glomerular filtration rate (eGFR), and left ventricular ejection fraction (LVEF). After adjusting for age, sex, BMI, smoking, alcohol, comorbidities, and traditional clinical factors, higher TML levels remained independently associated with HF (T3 vs. T1: adjusted odds ratio 5.41, 95% confidence interval 1.08-27.15, P = 0.040). Elevated TML was cross-sectionally associated with renal dysfunction in HF patients (odds ratio 32.12, 95% confidence interval 2.59-398.13, P = 0.007). The receiver operating characteristic (ROC) analysis yielded an area under the curve (AUC) of 0.673 (95% CI 0.570-0.776) for TML in distinguishing HF. In conclusion, elevated plasma TML is independently associated with HF and may indicate renal dysfunction in HF patients, supporting its potential as a clinically relevant biomarker for HF evaluation.