Providing Rapid Out of Hospital Acute Cardiovascular Treatment 3 (PROACT-3)

Background: The outcomes of acute cardiovascular symptom presentations are potentially modifiable with the use of biomarkers to accelerate accurate diagnosis. This randomized trial tested troponin and B-type natriuretic peptide before hospital guidance in patients with acute cardiovascular symptoms.

Methods: Patients with either chest pain or shortness of breath were randomized to usual care or biomarkers analyzed using a point-of-care device in the ambulance. The primary end point was time to final disposition (discharge from the emergency department or admission to hospital). The trial was stopped prematurely because of less than expected enrollment of patients of interest and no difference in the primary end point.

Results: We randomized 491 patients; 480 formed the final cohort. Patients were 49% male; median age 70 years; 42% had previous acute coronary syndrome; and 28% diabetes. The B-type natriuretic peptide level before hospital arrival was ≥ 100 pg/mL in 36.4%. Troponin was > 0.03 ng/mL in 13.4%; 3.6% had troponin > 0.1 ng/mL. After adjudication, 16% had acute coronary syndrome, 6.5% acute heart failure, 3.3% angina, and 74.2% another diagnosis. The primary end point was 9.2 (interquartile range, 7.3-11.1) hours in the biomarker group and 8.8 (interquartile range, 6.3-12.1) hours in the usual care group (P = 0.6). None died in the ambulance or in the emergency department: all-cause 30-day mortality was 2.1% (usual care) and 1.7% (biomarker).

Conclusions: To our knowledge, this is the first randomized trial of biomarkers before hospital arrival to guide emergency management of suspected acute cardiovascular disease which showed no benefit and was terminated early because of futility. The results have important implications for the use of biomarkers in emergency management of heart disease and for the design of future randomized trials on this important topic.