A systematic review 1 to compare the effectiveness of primary percutaneous transluminal coronary angioplasty (PTCA) and thrombolysis in acute myocardial infarction (MI) during a 6-month follow-up period was abstracted in DARE. The review included 10 studies with a total of 2725 subjects. The specific thrombolytic drug therapies were streptokinase, 3- and 4-hour tissue type plasminogen activator (tPA), 90-minute accelerated tPA and duteplase.
There was a statistically significant difference in favour of PTCA in mortality at 30 days (4.3% vs. 6.9%; RR 0.62, 95% CI: 0.44, 0.86, p=0.004). At 6 months the difference was still statistically significant (RR 0.73, 95% CI: 0.55, 0.98, p=0.04). The combined death and reinfarction rates at 30 days were 7.0% for PTCA and 12.9% for thrombolysis, with a sustained effect at 6 months (RR 0.60, 95% CI: 0.48, 0.75, p<0.0001). The risk of haemorrhagic stroke at 30 days was lower in the PTCA group (RR 0.06, 95% CI: 0.01, 0.5, p=0.009). The rate of major in-hospital bleeding was similar in both treatment groups.
Another review 2 abstracted in DARE included 23 studies with 7739 participants. Streptokinase was used in 8 studies (1837 participants) and t-PA in 15 (5902 participants). The patients assigned to PTCA were less likely to die (OR 0.73, 95% CI: 0.62, 0.86), have a nonfatal infarction (OR 0.35, 95% CI: 0.27, 0.45), have a haemorrhagic stroke (OR 0.05, 95% CI: 0.006, 0.35) or experience the combined end point of death, reinfarction or stroke (OR 0.53, 95% CI: 0.45, 0.63), than those assigned to thrombolysis. This applies for both short- and long-term outcomes. Major bleed was the only end point for which individuals were at greater risk when treated with primary PTCA (OR 1.30, 95% CI: 1.02, 1.65).
The latter systematic review was updated and abstracted in DARE 3. 22 studies with a total of 7518 subjects were included. Angioplasty was associated with a mean time delay (over and above time to thrombolysis) of 54.3 minutes. For this delay, mean event probabilities for all outcomes were lower for primary angioplasty than for thrombolysis at 1 month (mortality OR 0.68, 95% CI 0.46 to 1.01; non-fatal reinfarction OR 0.32, 95% CI 0.20 to 0.51; non-fatal stroke OR 0.24, 95% CI 0.11 to 0.50), and the results were similar at 6 months post-intervention. The benefit of primary angioplasty, over thrombolysis, depends on the additional time delay for angioplasty. Angioplasty is superior to thrombolysis where the time delay is 30 to 90 minutes. Where the time delay is around 90 minutes thrombolysis may be preferable, as assessed by 6-month mortality, but longer time delays are subject to considerable uncertainty.
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