Elevated lactate in acute heart failure patients with intracellular iron deficiency as identifier of poor outcome.

BACKGROUND: We believe that there is a physiological link between intracellular iron status (assessed by sTfR (soluble transferrin receptor)) and efficiency of energy production/consumption (assessed by lactate, a product of anaerobic cell metabolism), which may further impact the outcome of patients with acute heart failure (AHF).

AIM: To examine if elevated lactates (>2 mmol/L) accompanied with unmet cellular iron requirements (defined by sTfR of >1.59 mg/L) identify AHF patients with an unfavourable outcome.

METHODS: The study is a single centre, retrospective analysis of AHF patients in whom lactate and iron status was assessed on admission. The end-point of the study was 1-year mortality.

RESULTS: The study population consisted of 89 patients with mean± SD age: 65±13 (years), systolic blood pressure: 135±36 (mmHg), creatinine: 1.3±0.6 (mg/dL); median [25th-75th percentile] lactate on admission was 2.0 [1.6-2.6] (mmol/L). Seventeen (19%) patients had both lactate and sTfR below cutoff values (group 1). Thirty-eight (43%) individuals had separate elevation of either lactates or sTfR (group 2). The remaining 34 (38%) patients had both markers above predefined cutoffs (group 3). There was no difference in clinical and laboratory variables between the groups. During one-year follow-up 23 (26%) patients died. Group 3 had significantly higher mortality risk when compared to the rest of the population: HR (95% CI): 5.6 [2.2-14], p=0.0003 and the risk remained significant after adjustments for well-defined prognostic factors.

CONCLUSIONS: Patients with unmet iron cell requirements and hyperlactaemia on admission have significantly higher mortality risk when compared to individuals without those pathologies.