A randomized trial of the effects of early cardiac serum marker availability on reperfusion therapy in patients with acute myocardial infarction - The Serial Markers, Acute Myocardial Infarction and Rapid Treatment Trial (SMARTT)

OBJECTIVES The purpose of this study was to assess whether the immediate av ailability of serum markers would increase the appropriate use of thromboly tic therapy. BACKGROUND Serum markers such as myoglobin and creatine kinase, MB fraction (CK-MB) are effective in detecting acute myocardial infarction (AMI) in th e emergency setting. Appropriate candidates for thrombolytic therapy are no t always identified in the emergency department (ED), as 20% to 30% of elig ible patients go untreated, representing 10% to 15% of all patients with AM I. Patients presenting with chest pain consistent with acute coronary syndr ome were evaluated in the EDs of 12 hospitals throughout North America. METHODS In this randomized, controlled clinical trial, physicians received either the immediate myoglobin/CK-MB results at 0 and 1 h after enrollment (stat) or conventional reporting of myoglobin/CK-MB 3 h or more after hospi tal admission (control). The primary end point was the comparison of the pr oportion of patients within the stat group versus control group who receive d appropriate thrombolytic therapy. Secondary end points included the emerg ent use of any reperfusion treatment in both groups, initial hospital dispo sition of patients (coronary care unit, monitor or nonmonitor beds) and the proportion of patients appropriately discharged from the ED. RESULTS Of 6,352 patients enrolled, 814 (12.8%) were diagnosed as having AM I. For patients having AMI, there were no statistically significant differe nces in the proportion of patients treated with thrombolytic therapy betwee n the stat and control groups (15.1%, vs. 17.1%, p = 0.45). When only patie nts with ST segment elevation on their initial electrocardiogram were compa red, there were still no significant differences between the groups. Also, there was no difference in the hospital placement of patients in critical c are and non- critical care beds. The availability of early markers was asso ciated with more hospital admissions as compared to the control group, as t he number of patients discharged from the ED was decreased in the stat vers us control groups (28.4% vs. 31.5%, p = 0.023). CONCLUSIONS The availability of 0- and l-h myoglobin and CK-MB results afte r ED evaluation had no effect on the use of thrombolytic therapy for patien ts presenting with AMI, and it slightly increased the number of patients ad mitted to the hospital who had no evidence of acute myocardial necrosis. (C ) 2000 by the American College of Cardiology.