Myocardial Infarction Triage and Intervention Project--phase I - MITI I

Description:

Prehospital thrombolytics in acute myocardial infarction.

Hypothesis:

Prehospital initiation of thrombolytic therapy by paramedics could considerably reduce the time to treatment and possibly decrease the extent of myocardial necrosis in patients with acute coronary thrombosis.

Study Design

Study Design:

Patients Screened: Not given
Patients Enrolled: 2,742

Patient Populations:

<75 years old who were alert, oriented, and had ongoing chest discomfort of suspected cardiac origin for >15 minutes and <6 hours
Systolic blood pressure >80 and <180 mmHg
Diastolic blood pressure <120 mmHg and a systolic blood pressure difference between arms <20 mmHg (to minimize the possibility of aortic dissection)

Exclusions:

Any known bleeding condition
History of stroke, seizures, or transient ischemic attacks
Major surgery in the preceding 2 months
Gastrointestinal bleeding in the past year
Cancer or other terminal illnesses
Known liver disease or jaundice
Renal insufficiency
Insulin-dependent diabetes
History of active colitis
Recent trauma or central line placement
Warfarin therapy

Primary Endpoints:

Time to treatment

Drug/Procedures Used:

Thrombolytic therapy

Principal Findings:

677 patients had clinical findings consistent with possible AMI and no apparent risk of complications with potential thrombolytic therapy.

453 patients developed evidence of AMI in the hospital

163 of those 453 patients (36%) had met the strict prehospital screening history and examination criteria.

105 patients (23.9%) showed ST-segment elevation on the ECG, making them suitable candidates for prehospital thrombolytic treatment

The mean time to onset of chest pain to prehospital diagnosis was 72 ±52 minutes (median = 52 minutes). This was 73 ±44 minutes (median 62 minutes) earlier than the start of thrombolytic treatment in the hospital.

Interpretation:

Paramedic selection of appropriate patients for potential prehospital initiation of thrombolytic treatment is feasible with use of a directed checklist and cellular-transmitted ECG, and saves time. This strategy may reduce the extent and complications of infarction compared with results that can be achieved in a hospital setting.

References:

1. J Am Coll Cardiol 1990;15:925-31. Final results
2. Clin Cardiol 1990;13(Suppl 8):VIII-23-VIII-26. Review

Clinical Topics: Dyslipidemia, Stable Ischemic Heart Disease, Lipid Metabolism

Keywords: Thrombolytic Therapy, Myocardial Infarction, Chest Pain, Blood Pressure, Coronary Thrombosis, Fibrinolytic Agents, Electrocardiography, Tissue Plasminogen Activator


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