Early angiography before coronary angioplasty or bypass surgery compared with conventional care had similar outcomes after thrombolysis for myocardial infarction
ACP J Club. 1991 July-Aug;115:12. doi:10.7326/ACPJC-1991-115-1-012
SWIFT (Should We Intervene Following Thrombolysis?) Trial Study Group. SWIFT trial of delayed elective intervention v conservative treatment after thrombolysis with anistreplase in acute myocardial infarction. BMJ. 1991 Mar 9;302:555-60.
To determine whether a strategy of early angiography with a view to coronary angioplasty or bypass surgery improves outcomes compared with conservative management in patients with acute myocardial infarction treated with anistreplase.
Randomized, unblinded, multicenter trial of 12 months duration.
21 centers in the United Kingdom and Republic of Ireland.
800 of 993 patients aged < 70 years old with clinical and electrocardiographic features of acute infarction within the first 3 hours of symptom onset were included. Patients were excluded if thrombolysis was contraindicated. In addition, patients were excluded for life expectancy < 2 years or a perceived need for immediate surgical intervention. Of 800 patients randomized, survival and reinfarction data at 1 year were available for 743 (93%) and 646 (81%) patients, respectively.
All patients received 30 units of intravenous anistreplase followed by a standard regimen of heparin, warfarin, and timolol. Aspirin was not used routinely. Within 24 hours of receiving anistreplase, patients were randomized to early (within 48 hours of randomization) coronary angiography with a view to angioplasty or coronary bypass grafting (n = 397) or to conservative management with angiography and intervention only if clinically indicated (n = 403).
Main outcome measure
Death or reinfarction at 1 year.
During the initial hospitalization, 377 of 397 patients (95%) in the intervention group had angiography, 169 (43%) had coronary angioplasty, 59 (15%) had coronary bypass grafting, and 169 (43%) had no further intervention. Of 403 patients in the conventional care group, 54 (13%) had angiography, 12 (3%) had coronary angioplasty, and 7 (2%) had coronary bypass grafting. The 12-month mortality was 5.8% (23 patients) in the intervention group and 5% (20 patients) in the control group (odds ratio [OR] 1.18; 95% CI 0.64 to 2.10 P = 0.6). Reinfarction occurred in 15% and 13%, respectively (OR 1.16, CI 0.77 to 1.75, P = 0.4). Survival without reinfarction to 1 year did not differ between treatment strategies. (P = 0.32)
In patients with acute myocardial infarction treated with anistreplase, mortality and reinfarction rates were similar whether patients received routine early angiography with a view to intervention with coronary angioplasty or bypass grafting, or conventional therapy with angiography and interventions done only for clinical indications.
Source of funding: Not stated.
Address for article reprint: Professor D.P. de Bono, Department of Cardiology, Glenfield General Hospital, Leicester LE3 9QP, England, UK.
This important trial provides further support for the premise that "routine" coronary angiography with a view to "prophylactic" revascularization is not warranted after intravenous thrombolysis. 3 trials have evaluated the role of immediate angioplasty after thrombolysis with tissue plasminogen activator (rt-PA) and 1 after streptokinase (1-4). Despite differences in study design, the results were consistent among the trials. Early "prophylactic" angioplasty does not prevent reocclusion of the infarct-related artery or improve left ventricular function beyond that achieved with intravenous thrombolysis alone. Further, a trend occurred toward less favorable clinical outcomes among patients who had immediate angioplasty.
2 previous trials have evaluated the strategy of routine delayed angiography with a view to angioplasty after thrombolysis (5, 6). They showed that this strategy does not improve left ventricular function or prevent clinically important adverse outcomes such as death or reinfarction.
On the basis of the results of these trials, conventional medical therapy is warranted after thrombolysis in most patients. Invasive intervention should be used only if symptoms of recurrent ischemia develop. 2 subsequent trials (7, 8) showed similar results as those reported in the SWIFT trial.
David Massel, MD
Hamilton General HospitalHamilton, Ontario, Canada
8. Ellis SG, Mooney MR, George BS, et al. Randomized trial of late elective angioplasty versus conservative management for patients with residual stenoses after thrombolytic treatment of myocardial infarction. Circulation. 1992;86:1400-6.