Biomarker Panel Development for Early Identification of Worsening Heart Failure and Improved Post-acute Care

Overview

Heart failure is a complex clinical syndrome with high hospitalization rates and high mortality risks. While NT-proBNP is widely used in clinical practice to assist in diagnosis and assessment, its ability to detect prognosis in heart failure remains insufficient. Recent scientific research has found that phenylalanine in the blood and its endogenous toxic substance phenylpyruvate are closely related to impaired energy synthesis in heart muscle cells, making them highly promising next-generation long-term biomarkers. Our research team has previously developed a "risk score" prediction model that combines phenylpyruvate levels in the blood with clinical data; this project aims to further confirm its clinical value. Therefore, we cordially invite heart failure patients who are being followed up in the cardiology outpatient clinic to have their "phenylalanine" and "phenylpyruvic acid" concentrations measured in a small amount of blood. This data, combined with clinical data, will be used to calculate a "Risk Score" to identify high-risk heart failure patients earlier.

I. Background: Heart failure is a complex syndrome. Any abnormality in cardiac structure or function that affects ventricular congestion or ejection can lead to heart failure. Clinically, heart failure is classified into four categories based on the presence or absence of abnormal left ventricular ejection fraction (LVEF): heart failure with reduced ejection fraction (HFrEF), heart failure with mildly reduced ejection fraction (HFmrEF), heart failure with normal left ventricular ejection fraction (LVEF ≥ 50%), and heart failure with improved ejection fraction (HFimpEF) (previously LVEF ≤ 40%, followed by follow-up to LVEF \> 40%). The New York Heart Association functional classification (NYHA Fc) further classifies patients into grades I through IV based on the degree of limitation in physical activity. Patients diagnosed with HFrEF who exhibit symptoms of NYHA Fc grades 2 to 4 require guideline-directed medical therapy (GDMT). However, a good assessment strategy for long-term follow-up after treatment remains lacking. Among existing diagnostic and treatment strategies, NT-proBNP is the most widely used biomarker for diagnosis and prognostic assessment. However, its ability to identify early abnormalities of heart failure relapse, quantify metabolic abnormalities caused by heart failure, and detect endogenous toxicities caused by heart failure is still insufficient, and its assessment of heart failure prognosis is also imprecise. Elevated blood concentrations of phenylalanine and its metabolite phenylpyruvate are currently considered highly relevant to the pathophysiological mechanisms of heart failure exacerbation and can lead to the accumulation of phenylalanine and its downstream metabolite phenylpyruvate in the body fluids and tissues of heart failure patients, further worsening cardiac function. Furthermore, these metabolic disorders are closely associated with oxidative stress, mitochondrial dysfunction, and impaired energy synthesis. These alterations have been confirmed in animal models and clinical patients. They hold great potential as biomarkers for long-term monitoring by capturing early metabolic abnormalities and endogenous toxicities in heart failure. Therefore, this study focuses on phenylalanine and phenylpyruvate metabolites to assess their correlation with patient prognosis. In another part, we used the Chang Gung database for data analysis and integrated metabolite testing and clinical data into a "Risk Score" to identify high-risk patients. This aims to provide heart failure patients with more precise metabolic assessment and clinical management tools, thereby improving their quality of life and reducing disease-related mortality and hospitalization rates. II. Objectives: 1. To uniformly quantify phenylalanine and phenylpyruvate using high-order mass spectrometry and verify their correlation with the worsening of heart failure. 2. To use the developed "Risk Score" in prospective, multicenter, observational validation studies (including Chang Gung Memorial Hospital, Mackay Memorial Hospital, Cheng Hsin General Hospital, and National Taiwan University Hospital) to assess its clinical predictive ability, calibration, discrimination, and cross-center generalization ability in patients with chronic outpatient heart failure. III. Methods We will enroll patients at outpatient clinic at different hospitals. Then, fasting blood (3 ml) will be collected once to get the plasma after centrifugation. Phenylpyruvate (PPA) concentration will be measured by LC-MS/MS. Based on clinical information and the blood levels of NT-proBNP and PPA, a risk score will be calculated. For clinical outcomes, we will follow up patients' events of recurrent worsening heart failure, which will be explained in the primary and secondary outcome section. We will do statistical analysis to see the prognostic value of PPA concentrations and the risk scores.