Stable versus Dynamic Cardiac Symptom Characteristics Are Associated With Adverse Outcomes Among Individuals Transported by Ambulance for Suspected Acute Coronary Syndrome

Introduction: Acute coronary syndrome (ACS) is a potential life-threatening emergency; therefore, rapid diagnosis and life-saving reperfusion therapies are essential to prevent adverse outcomes. Patients with suspected ACS experience an array of symptoms, which cause patients to seek care (9-1-1 or self-transport) to the emergency department [ED]). Little is known, however, about the prognostic value of symptom characteristics experienced in the very early period of evolving ACS and its impact on adverse patient outcomes. The purpose of this study was to determine if early symptom changes reported in the prehospital period are associated with adverse outcomes. Methods Adults > 21 years of age with non-traumatic chest pain and/or anginal equivalent symptoms transported by ambulance were included. Cardiac symptoms were measured prospectively with the ACS Symptom Checklist, a validated 13-item tool that takes approximately one-minute to complete. Trained EMS personnel administered the ACS Symptom Checklist during ambulance transport (T1) and research specialists measured symptoms again in the ED (T2), after acute triage care was completed. Symptom changes were categorized as an increase, decrease, or both from T1 to T2. Changes in symptoms between T1 and T2 were defined as stable (0-3 symptoms) or dynamic ( > 4 symptoms). Adverse hospital outcomes included death, reinfarction, and/or new onset heart failure. Results To date, a total of 280 patients presenting to the ED by ambulance with suspected ACS have been enrolled (mean age 60.1 + 15.5 years; 51.2% female; 14.3% final diagnosis of ACS). Of 255(91.1%) patients with complete data, 143(51.1%) experienced stable symptoms and 112(40%) experienced dynamic symptoms. Patients with stable changes had significantly higher rates of adverse outcomes compared to patients with dynamic changes (11.9 versus 2.9%, p=0.007). Patients reporting shortness of breath at T1 or T2 were over 4 times likely to experience an adverse event (p=0.003, p=0007). Conclusions Patients with suspected ACS who have stable symptom changes were more likely to have an adverse hospital outcome. The underlying mechanism of plaque rupture in ACS may account for these differences in symptom characteristics but needs further study.