Left ventricular myocardial work efficiency identifies a mechanically inefficient heart failure phenotype across ejection fraction

Background Left ventricular ejection fraction (LVEF) remains the cornerstone for heart failure (HF) classification, yet it incompletely reflects myocardial performance and symptom burden. Myocardial work (MW), integrating myocardial deformation and afterload, may provide a more comprehensive assessment of mechanical efficiency across the HF spectrum. Purpose To explore whether left ventricular myocardial work efficiency (GWE) identifies a clinically relevant HF phenotype across different LVEF categories, independent of ejection fraction. Methods We studied 178 consecutive patients with chronic HF undergoing comprehensive transthoracic echocardiography. Patients were classified according to LVEF into HF with preserved EF (HFpEF, ≥50%), HF with mildly reduced EF (HFmrEF, 41–49%), and HF with reduced EF (HFrEF, ≤40%). LV myocardial work indices, including global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE), were derived from non-invasive LV pressure–strain loops using brachial blood pressure. Mechanical inefficiency was defined as LV GWE <90%, corresponding to the lower tertile of the study population. Clinical status was assessed using NYHA functional class, NT-proBNP levels, left atrial volume index, and E/e′. Results Reduced LV GWE was observed across all LVEF categories, including approximately one-third of patients with preserved LVEF. Patients with impaired LV GWE exhibited higher NT-proBNP levels (median 1,380 [IQR 820–2,240] vs 610 [360–1,090] pg/mL, p<0.01), worse NYHA functional class, higher E/e′ (16.2±4.8 vs 12.4±3.9, p<0.01), and larger left atrial volume index (38±9 vs 34±6 ml/m², p<0.01) compared with those with preserved GWE. LV GWE demonstrated greater discrimination for elevated NT-proBNP than GLS or LVEF (AUC 0.76 vs 0.64 and 0.61, respectively, p<0.01 for all comparisons)). Notably, patients with preserved LVEF but reduced GWE showed clinical characteristics comparable to those with reduced LVEF. The association between LV GWE and markers of HF severity was consistent across LVEF categories. Conclusions Left ventricular myocardial work efficiency identifies a mechanically inefficient heart failure phenotype across ejection fraction. By accounting for loading conditions, LV GWE provides complementary information beyond conventional measures and may refine phenotyping of HF across EF categories.