Extensive Dysregulation of Phenylalanine Metabolism Is Associated With Stress Hyperphenylalaninemia and 30-Day Death in Critically Ill Patients With Acute Decompensated Heart Failure.

BACKGROUND: Stress hyperphenylalaninemia predicts elevated mortality rates in patients with acute decompensated heart failure (ADHF). This study investigated the metabolic pathways underlying this association and identified a unique metabolic phenotype underlying the association between stress hyperphenylalaninemia and adverse outcomes in ADHF. METHODS AND RESULTS: This was a retrospective cohort study. We enrolled 120 patients with ADHF in an intensive care unit (60 with a phenylalanine level ≥112 µM, 60 with a phenylalanine level <112 µM), and 30 controls. Plasma phenylalanine-derived metabolites were measured, and participants were evaluated for 30-day death. Patients with ADHF had extensive activations of the alternative pathways for metabolizing phenylalanine, leading to the levels of phenylalanine-derived downstream metabolites 1.5 to 6.1 times higher in patients with ADHF than in the controls (all P<0.001). Extensive dysregulation of these alternative pathways significantly increased phenylalanine levels and contributed to a distinct metabolic phenotype, characterized by increased phenylalanine, tyrosine, homogentisic acid, and succinylacetone levels but decreased benzoic acid and 3,4-dihydroxyphenylalanine levels. Throughout the 30-day follow-up period, 47 (39.2%) patients died. This distinct metabolic phenotype was associated with an increased mortality rate (odds ratio, 1.59 [95% CI, 1.27-1.99]; P<0.001). A multivariable analysis confirmed the independent association of this metabolic phenotype, in addition to phenylalanine and tyrosine levels, with 30-day death. CONCLUSIONS: In patients with ADHF, extensive dysregulation of the alternative pathways for metabolizing phenylalanine was correlated with stress hyperphenylalaninemia and a distinct metabolic phenotype on the phenylalanine-tyrosine-homogentisic acid-succinylacetone axis. Both stress hyperphenylalaninemia and metabolic dysregulation on this axis were associated with poor outcomes.

Prognostic Significance of Phenylalanine in Heart Failure: Clinical Insights and Inter-Organ Crosstalk Snapshot.

Background: Heart failure (HF) remains a leading cause of morbidity and mortality globally, necessitating the identification of reliable prognostic biomarkers to guide therapeutic interventions. Recent clinical observations have underscored phenylalanine (PHE) as a prognostic marker in HF, although the mechanisms involving inter-organ crosstalk remain understood. Methods: This study adopted a dull approach, with a retrospective analysis of 550 HF patients to establish the prognostic value of pre-discharge PHE levels and a study on the inter-organ crosstalk of PHE among 24 patients. We analyzed the correlations between PHE concentrations and clinical outcomes, alongside a comprehensive examination of PHE metabolism across the skeletal muscle, liver, heart, kidney, and lung. Results: In the clinical prognostic analysis of 550 patients hospitalized for acute decompensated HF, elevated PHE levels (≥65.6 µM) were significantly and independently associated with increased all-cause mortality during a median follow-up of 4.5 years (log rank = 36.7, p < 0.001), underscoring its value as a prognostic marker in HF. The inter-organic crosstalk study elucidated the mechanism associated with PHE elevation in patients with HF, characterized by an increase in PHE output in skeletal muscle and a decrease in hepatic and cardiac PHE uptakes. Notably, PHE concentration gradients across these organs were correlated with HF severity, such as the NYHA functional class, B-type natriuretic peptide levels, and the presence of acute HF. Conclusions: Our findings confirm the prognostic significance of PHE in patients with HF and unveil the complex metabolic interplay among key organs that contribute to PHE dysregulation. These insights not only reinforce the importance of metabolic monitoring in HF management but also open avenues for therapeutic targets.

2024 Guidelines of the Taiwan Society of Cardiology for the Diagnosis and Treatment of Heart Failure with Preserved Ejection Fraction.

Heart failure with preserved ejection fraction (HFpEF) is a multi-organ systemic syndrome that involves cardiac and extra-cardiac pathophysiological abnormalities. Its growing prevalence causes a major public concern worldwide. HFpEF is usually associated with multiple comorbidities, and non-cardiovascular death is common in patients with HFpEF. In Asia, patients with HFpEF has a younger age, higher prevalence of diabetes and chronic kidney disease than Western countries. A 2-step diagnostic algorithm is recommended in this guideline. In the first step, the diagnosis of HFpEF can be made if patients have symptoms and/or signs of heart failure, left ventricular ejection fraction ≥ 50%, increased natriuretic peptide, and objective evidence of left atrial or left ventricular abnormalities or raised left ventricular filling pressure. If diagnosis is still uncertain, invasive or noninvasive stress test can be performed in the second step. Comorbidities need to be controlled in HFpEF. Weight reduction for obesity and supervised exercise training are recommended for HFpEF. For pharmacological therapy, diuretic is used to relieve congestion and sodium-glucose cotransporter 2 inhibitor, empagliflozin or dapagliflozin, is recommended to improve prognosis of HFpEF. The research on HFpEF is advancing at a rapid pace. It is expected that newer modalities for diagnosis and management of HFpEF could appear in the near future.

Combining Phenylalanine and Leucine Levels Predicts 30-Day Mortality in Critically Ill Patients Better than Traditional Risk Factors with Multicenter Validation.

In critically ill patients, risk scores are used; however, they do not provide information for nutritional intervention. This study combined the levels of phenylalanine and leucine amino acids (PLA) to improve 30-day mortality prediction in intensive care unit (ICU) patients and to see whether PLA could help interpret the nutritional phases of critical illness. We recruited 676 patients with APACHE II scores ≥ 15 or intubated due to respiratory failure in ICUs, including 537 and 139 patients in the initiation and validation (multicenter) cohorts, respectively. In the initiation cohort, phenylalanine ≥ 88.5 µM (indicating metabolic disturbance) and leucine < 68.9 µM (indicating malnutrition) were associated with higher mortality rate. Based on different levels of phenylalanine and leucine, we developed PLA scores. In different models of multivariable analyses, PLA scores predicted 30-day mortality independent of traditional risk scores (p < 0.001). PLA scores were then classified into low, intermediate, high, and very-high risk categories with observed mortality rates of 9.0%, 23.8%, 45.6%, and 81.8%, respectively. These findings were validated in the multicenter cohort. PLA scores predicted 30-day mortality better than APACHE II and NUTRIC scores and provide a basis for future studies to determine whether PLA-guided nutritional intervention improves the outcomes of patients in ICUs.