Inpatient versus outpatient onsets of acute myocardial infarction

Abstract

Background: There are few studies on patients suffering acute myocardial infarction (AMI) when already in hospital for other reasons; therefore, this study aimed to compare patients with in-hospital-onset AMI admitted for either medical or surgical reasons versus patients with outpatient-onset AMI.

Methods: Patients enrolled in the AMIS Plus registry from 2002 to 2014 were analyzed. The main endpoint was in-hospital mortality.

Results: Among 35,394 AMI patients, 356 (1%) had inpatient-onset AMI following hospital admission due to other pathologies (surgical 175, non-surgical 181). These patients were older (74 vs. 66 years; P<0.001), more often female (35% vs. 27%; P<0.001), had less frequently ST-elevation myocardial infarction (35.5% vs. 55.5%; P<0.001), but higher risk profiles: hypertension (83% vs. 62%; P<0.001), diabetes (28% vs. 20%; P=0.001), known coronary artery disease (54% vs. 35%; P<0.001), and more comorbidities (Charlson Comorbidity Index above 1 in 51% vs. 22%; P<0.001) than those with outpatient-onset AMI. Percutaneous coronary intervention was less frequently applied (OR 0.45; 95% CI 0.36-0.57), and they were less likely to be treated with aspirin (OR 0.43; 95% CI 0.37-0.59), P2Y12 blockers (OR 0.42; 0.34-0.52) or statins (OR 0.51; 95% CI 0.41-0.63). Crude mortality was higher (14.3% vs. 5.5%; P<0.001) and inpatient-onset AMI was an independent predictor of in-hospital mortality (OR 2.35; 95% CI 1.63-3.39; P<0.001).

Conclusions: Patients with in-hospital-onset AMI were at greater risk of death than those with outpatient-onset AMI. More work is needed to improve the identification of hospitalized patients at risk of AMI in order to provide the appropriate management.

Keywords: Acute myocardial infarction; Outcome; Symptom in hospital.