All the randomised clinical trials of primary angioplasty have shown a reduced incidence of stroke, recurrent ischaemia, and need for new target vessel revascularisation (TVR) compared to fibrinolysis, even in low risk patients.7 In selected subsets, primary angioplasty preserves left ventricular ejection fractionw4 w9 and benefits patients with anterior AMI treated up to 24 hours after symptom onset.w10 The favourable effects on mortality and reinfarction appear to be more pronounced among high risk patients, in particular those with haemodynamic evidence of failure.8 Benefits in this setting are also apparent from non-randomised data.9 A quantitative overview by Weaver and colleagues10 pooling 2606 patients showed that the mortality reduction obtained with primary angioplasty compared to fibrinolysis was approximately 32% (table 4.1). If this result can be reproduced everywhere, the magnitude of such treatment effect would be similar to that observed when fibrinolysis was used instead of placebo. However, these excellent results
54% TIMI 3
1% Stroke 25% late Occlusion
Figure 4.1 Nearly all patients with acute myocardial infarction (AMI) could potentially benefit from reperfusion treatment with fibrinolytics, but less than 50% will actually be treated; only 50-60% of those will achieve a TIMI 3 grade coronary flow, 10% will suffer from early reocclusion, 1% will have a stroke, and 20-30% will have late reocclusion. On the other hand, angioplasty can be offered to only 10% of patients with AMI, but more than 90% of these will actually be treated; 90% will achieve a TIMI 3 grade coronary flow, less than 5% will have reocclusion, and less than 0.1% will have a stroke.
derive from the experience of selected centres working under the specific requirements of randomised investigation and may not be easily achieved in the community setting, as is suggested by the results of large national registries9 w11 w12
The GUSTO II-B trial7 addressed this particular issue by testing the effect of angioplasty when performed mainly in low volume centres on a low risk population. In fact, GUSTO II-B showed a less favourable outcome of angioplasty than expected from other trials, which was caused by a higher event rate in the angioplasty arm rather than by a lower event rate in the fibrinolysis arm. Furthermore, 36% of patients allocated to fibrinolysis received an angioplasty before discharge, which may blunt the differences between the two strategies at six months. Crossover to angioplasty in patients initially randomised to pharmacological treatment is a common and important confounding factor when analysing differences in long term outcome."11 Long term benefit of angioplasty has been observed in the one year analysis of the SHOCK trial.8
The mortality reduction obtained with the emergency revascularisation strategy compared to the approach involving initial medical stabilisation was not significant at 30 days (46.7% v 56%, p = 0.11), but became so at six months (50.3% v 63.1%, p = 0.027) and increased further at one year (55% v 70%, p = 0.008). Albeit a negative study statistically, the number of lives saved per 1000 patients treated with the strategy of emergency revascularisation is the highest ever reported in a reperfusion trial (tables 4.1 and 4.2). The recent availability of long term results of primary angioplasty trials confirms the long lasting efficacy of the invasive approach also in patients without haemodynamic failure, despite some initial concern that early benefit may not be sustainedw13 (table 4.2).
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