Incidence and predictors of delirium on the intensive care unit after acute myocardial infarction, insight from a retrospective registry

Objectives: This study aimed to identify the incidence and potential risk factors for delirium after myocardial infarction (MI).

Background: Delirium is a common complication on intensive care units. Data on incidence and especially on predictors of delirium in patients after acute MI are rare.

Methods: In this retrospective study, all patients hospitalized for MI treated with coronary angiography in an university hospital in 2018 were included and analyzed. Onset of delirium within the first 5 days after MI was attributed to the MI and was defined by a Nursing Delirium screening scale (NuDesc) ≥2. This score is taken as part of daily care in every patient on intensive care unit three times a day by especially trained nurses.

Results: A total of 624 patients with MI (age 68.5 ± 13.2 years, ST-elevation MI 41.6%, hospital mortality 3.2%) were included in the study. Delirium was detected in 10.9% of all patients. In the subgroup of patients with a stay on the intensive care unit (ICU) for more than 24 hr (n = 229), delirium was detected in 29.7%. Hospital and ICU stay were significantly longer in patients with delirium (p < .001). Delirium was an independent predictor of prolonged ICU-stay. Independent predictors of delirium were age, dementia, alcohol abuse, cardiac arrest, hypotension, and leucocytosis. Infarct size or presentation with ST-elevation were not associated with incidence of delirium.

Conclusion: Development of delirium is frequent after acute MI and prolongs hospitalization. Incidence of delirium is associated with clinical instability, preexisting comorbidity, and age rather than MI type or size.