Metformin associated lactic acidosis in critically ill cardiac intensive care unit patients

Introduction

Metformin-associated lactic acidosis (MALA) is a potential lethal complication of metformin use, particularly in critically ill patients. While MALA has been studied in general patient populations, limited data are available on its occurrence in critically ill patients hospitalized in the cardiac intensive care unit (CICU). We aimed to describe the incidence, associated factors, and clinical course of MALA in critically ill patients admitted to the cardiac intensive care unit (CICU).

Materials and Methods

We included patients with cardiogenic shock caused by acute myocardial infarction (AMI-CS), heart failure (HF-CS) and complete atrio-ventricular block (CAVB-CS) and MALA hospitalized in the CICU of a tertiary center between January 1st 2023-December 1st 2024. The diagnosis and classification of cardiogenic shock were based on the Society for Cardiovascular Angiography and Interventions (SCAI) consensus statement. The diagnosis of MALA was confirmed by the occurrence of disproportionate acidosis with lactatemia that could not be attributed to hypoperfusion due to low cardiac output, following an in-depth review of patients` records.

Results

Overall, the incidence of CS with MALA among all patients during the study period was 8.3% (10/121 patients; 6 females; mean age 77.1±5 y/o). Of these, four patients presented with HF-CS, five patients with AMI-CS and one patient with CAVB-CS. Mean lactate level was 10.9±6.2 mmol/L. Six and five patients, respectively, underwent coronary angiography and percutaneous coronary intervention upon presentation. Renal replacement therapy was initiated in seven patients. Nine patients required any vasopressor or inotrope therapy. Mean CICU stay was 5.8±5.4 days and the mortality rate was 60% (six patients; 3 HF-CS, 2- AMI-CS and 1- CAVB-CS).

Conclusion

The incidence of MALA in patients with CS is substantial and is associated with high therapeutic burden and mortality rate. Early recognition of this pathology may improve patients outcomes; however larger studies are required to confirm this.