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Abstract

BackgroundThe existing classifications of heart failure (HF) remain a topic of debate within the cardiology community. Metabolomic profiling (MP) offers a means to define HF phenotypes based on pathophysiological changes, allowing for more precise characterization of patient groups with similar clinical profiles. MP may thus aid in refining HF classifications and offer a novel approach to phenotyping. MethodsMP was performed to 408 patients with different stages of HF. Patients with symptomatic HF were divided into phenotypes by left ventricle ejection fraction (LVEF). Liquid chromatography combined with mass-spectrometry were used for the MP. Data were analyzed using machine learning. The relationship between the incidence of all-cause death and LVEF trajectory changes and metabolomic clusters was evaluated. Follow-up period was 542 days [16;1271] in average. ResultsThe classification model achieved an AUC ROC - 0.91 for distinguishing of Stage A from Stage B and an AUC ROC - 0,97 for Stage B vs. Stage C using metabolomic analysis, models performance for differentiating Stages C and D was lower (AUC ROC 0.81). For HF phenotypes, the HFrEF, HFmrEF, and HFpEF model demonstrated moderate accuracy (AUC ROC 0.74), whereas the model distinguishing HFpEF from HF with EF 40% model, however, displayed low accuracy. Biostatistical processing of MP identified four metabolomic clusters, and 26 metabolites demonstrated the greatest significance (metabolites of the kynurenine and serotonin pathways of tryptophan catabolism, glutamine, riboflavin, norepinephrine, serine, long- and medium-chain acylcarnitines). Patients with reduced LVEF had the poorest prognosis (HR 1,896; 0,711-5,059), with an LVEF decrease linked to a threefold rise in all-cause mortality risk. Cluster 3 was associated with a 2,880-fold increase in all-cause mortality. ConclusionsOur findings suggest that MP provides an effective alternative approach for stratifying HF patients by stage. The observed metabolic similarities between HFpEF and HFrEF phenotypes highlight limitations in the current classification, underscoring the need to refine HF phenotyping into two primary categories. Hierarchical clustering by metabolomic profile produced a high-accuracy model, supporting MP as a valuable tool for HF classification. Novelty and SignificanceO_ST_ABSWhat Is Known?C_ST_ABSO_LIClassifying HF by stages offers the advantage of incorporating preventive aspects, however, diagnosing Stage B can be challenging due to the necessity of analyzing numerous parameters for verification. C_LIO_LIThe classification by LVEF, particularly distinguishing HFmrEF, remains controversial because of limited evidence for specific treatment strategies. C_LIO_LIMetabolomic profiling (MP) offers a means to identify unique pathophysiological changes across phenotypes, presenting a promising approach for diagnosing HF and developing targeted therapies. C_LI What New Information Does This Article Contribute?O_LIThis study demonstrates high accuracy in HF stage classification by integrating chromatography-mass spectrometry data with bioinformatic analysis through multiparametric machine learning (ML) models. C_LIO_LISimilarities between metabolomic profiles of patients with LVEF View larger version (65K): org.highwire.dtl.DTLVardef@173f141org.highwire.dtl.DTLVardef@e41c97org.highwire.dtl.DTLVardef@11386eorg.highwire.dtl.DTLVardef@8fee01_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstractC_FLOATNO EF - ejection fraction; HF - heart failure; HFmrEF - heart failure with mid-range ejection fraction; HFpEF - heart failure with preserved ejection fraction; HFrEF - heart failure with reduced ejection fraction. C_FIG

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02 /Specification & Classification

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Claude Opus 5.5 · xhigh effort · 8 Nov 2026 · from the full text of version 1 (14 Nov 2024) · CC BY 4.0

Plasma metabolomics with random forests separated heart failure stage B from C (AUC 0.97) and HFpEF from EF <50% (AUC 0.96), suggesting HFmrEF resembles HFrEF metabolically.

Heart failure (HF) is classified by stage and by left ventricular ejection fraction (LVEF), yet diagnosing stage B requires many imaging and biomarker measurements and the mid-range EF group (HFmrEF) lacks specific treatment evidence. The study tests whether targeted plasma metabolomics plus machine learning can reproduce these classes, place HFmrEF, and define metabolism-based subgroups linked to mortality.

Key results

  1. SuggestedRandom forest models trained on plasma metabolite profiles separated asymptomatic stage B from both stage A and symptomatic stage C with high discrimination. Separating stage C from stage D was weaker.

    AUC ROC with a 70%/30% discovery/test split: stage B vs C 0.97 (accuracy 0.89, F1 0.89); stage A vs B 0.91 in abstract, 0.93 in Figure 2A legend (accuracy 0.88); stage C vs D 0.81 in abstract, 0.89 in legend (accuracy 0.79). · Abstract; Statistical analysis; Metabolomic profile in patients with different…; Figure legends

  2. SuggestedA three-class HFpEF/HFmrEF/HFrEF model performed only modestly. Grouping HFmrEF with HFrEF (HFpEF vs EF <50%) separated the groups well, but grouping HFmrEF with HFpEF did not. The authors read this as HFmrEF being metabolically closer to HFrEF.

    Three-class model AUC ROC 0.74 (abstract) or 0.72 (legend), accuracy 0.66; HFpEF vs EF <50% AUC 0.96, accuracy 0.88; HFrEF vs EF >40% AUC 0.66, accuracy 0.70. Groups: HFrEF 81, HFmrEF 50, HFpEF 87 patients. · Abstract; Study population; Metabolomic profile in patients with different…; Figure legends

  3. ShownWard clustering of stage C/D metabolomes gave four clusters: cluster 3 with kynurenine-pathway activation, more riboflavin and less serine; cluster 4 with raised acylcarnitines; cluster 2 with high norepinephrine; cluster 1 with low serotonin-pathway metabolites.

    A random forest recovered the 4 clusters with AUC ROC 0.96, accuracy 0.95, F1 0.95 (max_depth=30, n_estimators=20). The 26 top metabolites included 3-OH-anthranilic, quinolinic and xanthurenic acids (raised in cluster 3), glutamine, norepinephrine, serine and medium/long-chain acylcarnitines. · Statistical analysis; Clustering by metabolomic profile; Figure legends

  4. SuggestedIn Cox models, metabolomic clusters 3 and 4 carried the highest all-cause mortality risk among symptomatic patients, although cluster 3 also showed the best three-year survival after early deaths. Cluster 3 stayed a significant predictor, alongside age and declining LVEF, in a combined Cox model.

    Cluster Cox model: cluster 4 HR 2.586 (1.047 to 6.386), p = 0.041; cluster 3 HR 1.995 (CI 0.986 to 4.036), p = 0.04. Survival curves across clusters, likelihood ratio test p = 0.082075. Combined model: LVEF decrease about threefold risk, cluster 3 2,88-fold. · Survival of patients with chronic heart failure; Predictors of all cause death

  5. SuggestedMortality during follow-up was substantial. In the subset with serial records, patients whose LVEF fell had the worst early survival regardless of baseline EF, but differences between trajectory groups were not statistically significant.

    57 (26.14%) deaths among 218 followed patients; 2-year survival 74.8%, three-year death risk 41.9%. Of 98 with records, 16 (16.3%) had EF decline and 33 (33.7%) improved; decreased-EF HR 1.896 (0.711 to 5.059) vs improved-EF HR 0.829 (0.325 to 2.114); p = 0.337096. · Clinical follow-up; Survival of patients with chronic heart failure; Predictors of all cause death

Methods, data and reproducibility

Targeted LC-MS/MS with phenyl isothiocyanate derivatization quantified plasma metabolites in 408 patients. Random forest classifiers (70/30 split, grid-search tuning) tested stage and LVEF contrasts, Ward hierarchical clustering defined metabolic clusters, and Cox and Kaplan-Meier models linked clusters and LVEF trajectory to all-cause death.

  • Patients across AHA heart failure stages A to D, including stage A (130) and stage B (60), mainly with hypertension or coronary artery disease · human · n = 408
  • Symptomatic (stage C/D) HF patients grouped by LVEF (HFrEF 81, HFmrEF 50, HFpEF 87) and followed for all-cause death (average 542.37 days) · human · n = 218
  • Symptomatic HF subset with medical records and repeat echocardiography, used for LVEF trajectory and therapy analysis · human · n = 98
Methods & tools
Targeted LC-MS/MS (Agilent 1200 HPLC, Agilent 6460 triple quadrupole, scheduled MRM), Phenyl isothiocyanate (PITC) derivatization with isotope-labeled internal standards, Acquity UPLC BEH C18 column, Agilent MassHunter, scikit-learn 1.5.2 (random forest, PCA, GridSearchCV), Simca-P+ 14.1 (Ward hierarchical cluster analysis), pandas 2.2.3, numpy 2.1.2, scipy 1.14.1, SPSS 25.0, R 3.6.2, Kaplan-Meier survival analysis, Cox proportional hazards regression
Reagents & environment
Python 3.11 with pandas 2.2.3, numpy 2.1.2, scipy 1.14.1 and scikit-learn 1.5.2; SPSS 25.0; R 3.6.2; Simca-P+ 14.1; Agilent MassHunter for LC-MS/MS quantification.
Reproducibility gaps
No code repository, data deposition or data availability statement is given; MRM transitions, most random forest hyperparameters and per-model metabolite rankings are reported only in supplementary Tables S1-S11.
Limitations (5)
  • The relatively small sample size may reduce the accuracy of the machine learning classifiers, and larger cohorts are needed to establish sensitivity and specificity. · stated by the authors
  • Repeat echocardiography was done only for patients who regularly attended the center (n = 98), so LVEF trajectory data may be incomplete and temporal dynamics are hard to assess. · stated by the authors
  • The lack of significant survival differences between EF trajectory groups may reflect small group sizes. The late mortality rise in the improved-EF group after 1000 days should be read with caution given few participants. · stated by the authors
  • Reported figures conflict across sections: stage A vs B AUC 0.91 (abstract) vs 0.93 (Figure 2 legend), stage C vs D 0.81 vs 0.89, three-class model 0.74 vs 0.72, cluster 3 effect 2,880-fold vs 2,88-fold; cluster 3 HR CI 0.986 to 4.036 spans 1 yet p = 0.04. · noted in this summary
  • The cluster classifier (AUC 0.96) predicts labels derived by clustering the same metabolomic data, so it measures cluster separability rather than diagnostic validity. All models rely on one cohort with a single random split and no external validation. · noted in this summary

Who should read:Read this if you study heart failure classification or plasma metabolomic biomarkers and want evidence on stage B detection, where HFmrEF belongs, and metabolism-defined prognostic clusters.

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