Hemoglobin in cardiogenic shock: the lower, the poorer survival.

Background: Cardiogenic shock (CS) is a severe hemodynamic condition with high mortality. Although extremely frequent in daily practice, the impact of anemia in CS is largely unknown. This study focuses on the consequences of low hemoglobin (Hb) level on the outcomes of CS patients.

Methods: FRENSHOCK is a prospective registry including 772 CS patients from 49 centers. One-month and one-year mortalities were analyzed according to the admission level of Hb.

Results: Among 754 patients, 71.8% were male, with a mean age of 65.8 (± 14.8) years, and 361 (47.9%) presenting with anemia. Four groups were defined, depending on admission Hb levels by quartiles: Q1: Hb < 11.0 g/dL, Q2: Hb 11-12.6 g/dL, Q3: Hb > 12.6-14 g/dL, and Q4: Hb > 14.0 g/dL. Patients from the Q1 group required more frequent renal replacement therapy and norepinephrine. A significant increase in all-cause mortality was observed across Hb quartiles at 1 month (Ptrend = 0.035) and 1 year (Ptrend < 0.01). Q1 patients had 1.64 times higher mortality at 1 month (1.09-2.47, p = 0.02) and 2.53 times higher mortality at 1 year (1.84-3.49, p < 0.01) compared to Q4. The negative effect of low Hb level was confirmed in multivariate Cox regression adjusted for baseline characteristics, and was stronger in men, non-ischemic CS, patients without CKD and patients aged < 67 years.

Conclusion: Anemia is a common condition frequently intertwined with CS worsening both short- and long-term mortality. Further randomized studies are warranted to understand its mechanisms and adapt the transfusion strategy.