The prognostic role (if any) of lactate for early mortality in patients with ST-elevation myocardial infarction (STEMI) submitted to primary percutaneous coronary intervention (PCI) is so far not elucidated. We therefore assessed whether lactic acid (LA) was a prognostic predictor for early mortality in 807 patients with STEMI submitted to primary PCI consecutively admitted to our intensive cardiac care unit (ICCU) from January 1, 2006, to December 31, 2009.

Higher levels of LA were found in older patients (P = .025) and were associated with a progressive decline in estimated glomerular filtration rate (P < .001) and in ejection fraction (P < .001). The increase in LA values paralleled the progressive increase in glucose values, peak glycemia, troponin I, N-terminal pro–brain natriuretic peptide, and uric acid (P < .001, P < .001, P < .001, P = .018, and P = .006, respectively). The in-ICCU mortality rate was highest in the third LA tertile (P < .001). Lactate levels were independent predictors for in-hospital mortality only in patients with Killip classes III to IV (odds ratio [OR], 1.17; 95% confidence interval [CI], 1.05-1.30, P = .003). In addition, age (OR, 1.11; 95% CI, 1.03-1.19, P = .006) and leukocytes (OR, 1.17; 95% CI, 1.03-1.33, P = .015) were independent predictors for in-hospital mortality when adjusted for PCI failure.

In patients with STEMI submitted to primary PCI, blood lactate is a prognostic marker for early mortality only in the subgroup with advanced Killip class. The degree of hemodynamic impairment (as indicated by Killip class), of myocardial ischemia (as inferred by troponin I), and glucose values are the main factors influencing lactate concentrations in the early phase of STEMI.