Should We Intervene Following Thrombolysis? - SWIFT

Description:

Invasive vs. conservative management after APSAC thrombolysis for acute MI.

Hypothesis:

To assess routine angiography and revascularization versus conservative treatment after thrombolysis with anistreplase (APSAC) in acute myocardial infarction.

Study Design

Study Design:

Patients Screened: 993
Patients Enrolled: 800
Mean Follow Up: 12 months
Mean Patient Age: 56
Female: 18

Patient Populations:

Age < 70 years
Clinical evidence of first acute myocardial infarction
Three hours or less after the onset of major symptoms
ST elevation > 0.1 mV in two or more standard leads or > 0.2 mV in two or more precordial leads

Exclusions:

Contraindications to thrombolysis
Life expectancy < 2 years
Perceived need for immediate surgical intervention.
Cardiogenic shock
History of bleeding diathesis or recent bleeding
Cerebrovascular accident within 3 months
Surgery or major trauma within 3 months
Previous streptokinase or anistreplase treatment within 6 months
Hypertension > 200/100 mmHg
Menstruation or possibility of pregnancy
Pulmonary edema

Primary Endpoints:

Death or reinfarction within 12 months

Secondary Endpoints:

Angina
LV function
Duration of hospital stay

Drug/Procedures Used:

Routine early coronary angiography, or angiography followed by intervention.

Concomitant Medications:

APSAC (30 U IV over 5 min); heparin, warfarin, timolol.

Principal Findings:

A total of 397 patients were randomised to early angiography; of these, 377 patients (95%) underwent arteriography. Revascularization was performed in 60% of patients catheterized: 169 underwent angioplasty and 59 underwent CABG.

Of the 403 patients randomized to conservative care, 13% underwent angiography, and 19 required revascularization during the initial admission (12 PTCA, 7 CABG).

One year infarction-free survival did not differ between treatment strategies. (P = 0.32)

By 12 months mortality was slightly higher in the early angiography group (5.8%) compared to the conservative group (5.0%), although this difference was not statistically significant (odds ratio [OR] 1.18; 95% CI 0.64 to 2.10 P = 0.6). Rates of reinfarction were also similar in the two groups (15.1% invasive vs 12.9% conservative, (OR 1.16, CI 0.77 to 1.75, P = 0.4)).

No significant differences in rates of angina or rest pain were found at 12 months.

Left ventricular ejection fraction at three and 12 months was the same in both groups.

Median hospital stay was longer in the intervention group (11 days vs. 10 days; p less than 0.0001).

Interpretation:

Several trials have evaluated the utility of routine coronary angiography following alteplase or streptokinase thrombolytic therapy for myocardial infarction. The SWIFT study is consistent with the finding that routine angiography and 'prophylactic' revascularization is not warranted after intravenous thrombolysis.

For most patients given thrombolytic treatment for acute myocardial infarction, a strategy of angiography and intervention is most appropriate when required for clinical indications.

References:

1. Brit Med J 1991;302:555-60. Final results

Clinical Topics: Dyslipidemia, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Lipid Metabolism, Novel Agents, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: Odds Ratio, Thrombolytic Therapy, Myocardial Infarction, Streptokinase, Coronary Angiography, Stroke Volume, Anistreplase, Tissue Plasminogen Activator, Angioplasty


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