Hyperlactataemia and acid–base disturbances in normotensive patients with acute heart failure

Acute heart failure (AHF) may be associated with low-tissue perfusion and/or hypoxaemia leading to increased lactate levels and acid–base perturbations. Few data are available on the clinical significance of elevated lactate levels and primary acid–base disorders in the setting of AHF.

Arterial blood gas was obtained at admission in 4012 normotensive (systolic blood pressure ≥ 90 mmHg) patients with AHF. The association between lactate levels and acid–base status and in-hospital mortality was determined using multivariable logistic regression. Hyperlactataemia (>2 mmol/L) was present in 38.0% of patients and was strongly associated with markers of sympathetic activation, such as hyperglycaemia. Hyperlactataemia was present in 31.0%, 43.7%, and 42.0% of patients with normal pH, acidosis, and alkalosis, respectively. In-hospital mortality occurred in 16.4% and 11.1% of patients with and without hyperlactataemia [adjusted odds ratio (OR) 1.49; 95% confidence interval (CI) 1.22–1.82, P < 0.0001]. Compared with normal pH, the OR for in-hospital mortality was 2.48 (95% CI 1.95–3.16, P < 0.0001) in patients with acidosis and 1.77 (95% CI 1.32–2.26, P < 0.0001) in patients with alkalosis. The risk for in-hospital mortality was high with acidosis (18.1%) or alkalosis (10.4%) even with normal lactate. The most common primary acid–base disturbances included metabolic acidosis, respiratory acidosis, and metabolic alkalosis with respiratory acidosis having the highest risk for in-hospital mortality.

Hyperlactataemia was common in patients without hypotension and was associated with increased risk for in-hospital mortality. Hyperlactataemia is not associated with any specific acid–base disorder. Acute heart failure patients also present with diverse acid–base disorders portending increased in-hospital mortality.