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) - SMARTT

Description:

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).

Hypothesis:

To assess whether the immediate availability of serum markers such as myoglobin and creatine kinase, MB fraction (CK-MB) would increase the appropriate use of thrombolytic therapy in patients with acute myocardial infarction (AMI).

Study Design

Study Design:

Patients Enrolled: 6352

Drug/Procedures Used:

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 hospital admission (control) of patients presenting to emergency department (ED) with chest pain suggestive of acute coronary syndromes.

Principal Findings:

AMI was diagnosed in 814 of 6,352 patients enrolled (12.8%). Patients having AMI treated with thrombolytic therapy did not differ between the stat and control groups (15.1% vs. 17.1%, P = 0.45; primary endpoint). When only patients with ST segment elevation on their initial electrocardiogram were compared, there were no significant differences between the groups (39.5% for stat vs 42.1% for control; p = 0.70). Reperfusion therapy (thrombolytic or PTCA) was also similar for the stat and control groups (58.5% vs 64.2%, p = 0.42). There was no difference in the hospital placement of patients in critical care and non--critical care beds (secondary endpoint). The availability of early markers was associated with more hospital admissions as compared to the control group, as the number of patients discharged from the ED was decreased in the stat versus control groups (28.4% vs. 31.5%, P = 0.023).

The availability of 0- and 1-h myoglobin and CK-MB results after ED evaluation had no effect on the use of thrombolytic therapy for patients presenting with AMI, but increased the number of patients admitted to the hospital without evidence of acute myocardial necrosis.

Interpretation:

Physicians do not institute thrombolytic/reperfusion therapy in absence of ECG evidence of ST elevation or new left bundle branch block. However, such patients may benefit from increased surveillance with frequent serial ECGs to identify ST elevation AMI so that an appropriate reperfusion strategy can be promptly instituted. In the current study, only 60% of patients in both groups received thrombolytic or reperfusion therapy within 3 hours of presentation. This represents a group where opportunity may exist to further improve care.

References:

1. Gibler WB, Hoekstra JW, Weaver WD, et al. J Am Coll Cardiol 2000;36:1500-6.

Clinical Topics: Acute Coronary Syndromes, Arrhythmias and Clinical EP, ACS and Cardiac Biomarkers, EP Basic Science

Keywords: Thrombolytic Therapy, Myocardial Infarction, Acute Coronary Syndrome, Biological Markers, Myoglobin, Creatine Kinase, MB Form, Bundle-Branch Block, Emergency Service, Hospital, Electrocardiography, Critical Care


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