Cardiac mechanical efficiency in patients with cardiogenic shock

BACKGROUND: Cardiogenic shock (CS) is characterized by impaired left ventricular (LV) mechanical performance and adverse remodeling. We evaluated whether transthoracic echocardiography (TTE)-derived modified cardiac efficiency (mCE), integrating stroke work and residual LV volume, is associated with short- and long-term mortality in CS and whether its prognostic value differs by shock etiology. METHODS: In this retrospective cohort study, consecutive adults admitted with CS to the cardiac intensive care unit at Mayo Clinic (2007-2018) were included if TTE was performed within 24 hours. mCE was calculated as (stroke volume × estimated LV end-systolic pressure) divided by LV end-systolic volume and categorized into quartiles. Primary outcome was in-hospital mortality; secondary outcome was 1-year mortality. Multivariable logistic and Cox models adjusted for illness severity, comorbidity burden, shock etiology, cardiac arrest, vasoactive therapy, and mechanical circulatory support. RESULTS: Among 667 patients, median mCE was 48 mmHg (IQR 32-74). In-hospital mortality was 28% and increased stepwise across decreasing mCE quartiles. The lowest quartile had a 2.5-fold higher adjusted odds of in-hospital death (OR 2.53; 95%CI: 1.49-4.37; P < 0.001). One-year mortality was 41%; the lowest quartile had a twofold higher adjusted hazard of death (HR 2.05; 95%CI: 1.45-2.89; P < 0.001). Associations were stronger in acute coronary syndrome-related CS (interaction P = 0.035 for in-hospital; P = 0.015 for 1-year). Within the lowest quartile, reduced systolic pressure further amplified mortality risk. CONCLUSIONS: Early TTE-derived mCE was independently associated with short- and long-term mortality in CS, particularly in acute coronary syndrome-related CS, and captured the interaction between ventricular remodeling and mechanical performance underlying high-risk phenotypes.