3384 Serum Metabolites from the Trimethylamine Pathway Associate with Left Ventricular Diastolic Function: The Bogalusa Heart Study
Authors: Razavi Alexander C. , Fernandez Camilo , Mi Xuenan , He Jiang , Bazzano Lydia , Nierenberg Jovia , Li Shengxu , Kelly Tanika N. 
Published: March 2019

OBJECTIVES/SPECIFIC AIMS: This population-based study aims to assess the individual and collective relationship between TMA-associated metabolites and echocardiographic parameters of left ventricular diastolic function. METHODS/STUDY POPULATION: The study cohort consisted of 1,039 adult participants of the Bogalusa Heart Study (35.13% black, 57.94% female, aged 33.60 to 57.47 years). Left ventricular diastolic function was assessed via two dimensional and tissue Doppler echocardiography. Echocardiographic parameters of diastolic function included peak early (E, cm/s) and late transmitral flow velocities (A, cm/s), septal mitral annular velocity (e’, cm/s), left ventricular isovolumic relaxation time (IVRT, ms), and peak early diastolic transmitral flow velocity deceleration time (DT, ms). Metabolomic analysis of fasting serum samples was conducted via ultrahigh performance liquid chromatography-tandem mass spectroscopy. Six metabolites in the TMA pathway, carnitine, choline, TMAO, betaine, ergothioneine, dimethylglycine, and two composite variables, the betaine/choline ratio as well as the weighted sum of the six TMA-associated metabolites (TMA score), were selected a priori and tested for association with echocardiographic parameters of diastolic function. Raw metabolite values were divided by their respective standard deviation to create an exposure variable for each individual metabolite. The betaine/choline ratio was calculated utilizing the raw value of each metabolite. The z-score method was used to transform the six metabolites to the same scale and these values were used to calculate the TMA score. Multivariable-adjusted linear regression models were employed to assess the relationship of TMA-associated metabolites with echocardiographic measures of diastolic function. Covariates adjusted for included sex, age, race, education, alcohol drinking, cigarette smoking, heart rate, systolic blood pressure, glomerular filtrate rate, body mass index, low density lipoprotein cholesterol, high density lipoprotein cholesterol, hemoglobin A1c, serum triglycerides, as well as blood pressure-, lipid-, and glucose-lowering medications. RESULTS/ANTICIPATED RESULTS: After stringent Bonferroni correction for multiple testing, four TMA-associated metabolites as well the TMA score were significantly associated with diastolic function. TMAO was inversely associated with IVRT (ß = −0.002 (0.00); p-value = 2.00E-03). Betaine (ß = 0.40 (0.08); p-value = 2.10E-07), carnitine (ß = 0.30 (0.07); p-value = 7.80E-05), dimethylglycine (ß = 0.27 (0.07); p-value = 3.00E-04), and the TMA score (ß = 0.10 (0.02); p-value = 3.40E-05), were positively associated with the septal E/e’ ratio. No significant associations were observed between metabolites or metabolite composite scores from the TMA pathway and the E/A ratio or DT. DISCUSSION/SIGNIFICANCE OF IMPACT: This is the first population-based study to assess the role of TMA-associated metabolites in left ventricular diastolic function. Betaine, carnitine, dimethylglycine, and a metabolite score combining serum metabolites from the TMA pathway were positively associated with the septal E/e’ ratio, suggesting that a higher concentration of TMA-associated metabolites correlates with impaired diastolic function. These results suggest that both individual and grouped metabolites from the TMA pathway may serve as early biomarkers for pre-clinical diastolic dysfunction, an important causal factor for HFpEF. Future longitudinal, multi-omic studies incorporating microbiome, metabolomic and dietary analyses are needed to characterize the risk of ventricular diastolic function and HFpEF in the setting of exposure to TMA-associated metabolites.