Heart failure with reduced ejection fraction patients defy uniform management despite guideline-directed medical therapy, prompting researchers to apply machine learning across clinical, ECG, echocardiographic, biomarker, and proteomic data from 564 VICTORIA trial participants. The analysis was published in the Circulation: Heart Failure. 
The Three Faces of HFrEF
Phenogroup 1 represents younger patients optimally treated with guideline-directed medical therapy who are least likely to have implantable cardioverter defibrillators and serve as the lowest-risk reference cohort. Phenogroup 2 carries the highest prevalence of atrial fibrillation alongside pathological Q-waves, suggesting prior infarction or scar burden, positioning this group at intermediate risk. Phenogroup 3 encompasses the oldest patients exhibiting biventricular dysfunction and advanced renal disease, manifesting the highest event rates with a hazard ratio of 7.0 compared to phenogroup 1.
GDF-15 Emerges as Master Biomarker
Multinomial logistic regression identified growth differentiation factor 15 as the most critical protein discriminating all three phenogroups in both VICTORIA and the external validation cohort BIOSTAT-CHF. This mitokine integrates multisystem physiologic stress beyond traditional markers, offering superior phenogroup separation.
External Validation Confirms Phenogroup Stability
BIOSTAT-CHF replication demonstrated phenogroup 3 consistency through older age, renal dysfunction, and elevated event rates, establishing these machine learning-derived subgroups as robust across independent international datasets rather than cohort-specific artifacts.
Precision Heart Failure Management Achieved
Machine learning transforms HFrEF from a heterogeneous syndrome to three biologically coherent phenogroups spanning sevenfold outcome differences, externally validated across continents with GDF-15 as master discriminator. Clinicians gain precision risk stratification, while patients gain therapies matched to underlying pathophysiology. HFrEF management enters its precision medicine era.