Factors that influence the use of ambulance in acute coronary syndrome.

Background: National guidelines recommend activation of the emergency medical service by patients who have symptoms of acute coronary syndrome (ACS). In spite of this, only 50% to 60% of persons with myocardial infarction initiate care by using the emergency medical service. The aim of this study was to define factors influencing the use of ambulance in ACS.

Methods: The method used in this study was a national survey comprising intensive cardiac care units at 11 hospitals in Sweden; 1,939 patients with diagnosed ACS and symptom onset outside the hospital completed a questionnaire a few days after admission.

Results: Half of the patients went to the hospital by ambulance. Factors associated with ambulance use were knowledge of the importance of quickly seeking medical care and calling for an ambulance when having chest pain (odds ratio [OR] 3.61, 95% CI 2.43-5.45), abrupt onset of pain reaching maximum intensity within minutes (OR 2.08, 1.62-2.69), nausea or cold sweat (OR 2.02, 1.54-2.65), vertigo or near syncope (OR 1.63, 1.21-2.20), ST-elevation ACS (OR 1.58, 1.21-2.06), increasing age (per year) (OR 1.03, 1.02-1.04), previous history of heart failure (OR 2.48, 1.47-4.26), and distance to the hospital of >5 km (OR 2.0, 1.55-2.59). Those who did not call for an ambulance thought self-transport would be faster or did not believe they were sick enough.

Conclusions: Symptoms, patient characteristics, ACS characteristics, and perceptions and knowledge were all associated with ambulance use in ACS. The fact that knowledge increases ambulance use and the need for behavioral change pose a challenge for health-care professionals.