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Stent or PTCA for acute myocardial infarction?

Review
Results
Comment
In acute myocardial infarction there is now a choice of reperfusion strategies between balloon angioplasty and the use of a stent. Which is better? A meta-analysis suggests that the use of stents leads to lower rates of target vessel revascularisation and major adverse cardiac outcomes [1].

Review


The review sought trials comparing randomised trials of primary stent implantation compared with primary balloon angioplasty for acute myocardial infarction having outcomes of interest. These outcomes were death, reinfarction, target vessel revascularisation and major adverse cardiac events (including death, reinfarction, disabling stroke and target vessel revascularisation). MEDLINE was searched to December 2000, as well as abstracts of medical meetings carried in major cardiology journals and reference lists of papers and reviews.

Outcomes had to be reported for at least six months of follow up, and for each trial results at the longest follow up were used. Investigators were contacted when results of particular outcomes were not reported.

Results


There were nine included studies varying in size from 88 to 2,082 patients (4,120 in total). Five trials have yet to be published in full, but contained over half of the patient information. In all studies patients were within 24 hours of onset of symptoms, and vessel diameters were generally larger than 2.5 to 4.5 mm. Six different stents were represented, one with and one without heparin coating. Follow up was six months for about 2,400 patients.

There was no difference between procedures for death or reinfarction, occurring at about 2-4% (Table 1).

Table 1: Outcomes in randomised trials comparing stents and PTCA in acute myocardial infarction

    Patients with events/total (%)    
Outcome Number of trials Stent PTCA Relative risk (95%CI) NNT (95%CI)
Death 9 77/2050 (3.8) 75/2070 (3.6) 1.0 (0.8 to 1.4) Not calculated
Reinfarction 7 40/1873 (2.1) 56/1889 (3.0) 0.7 (0.5 to 1.1) Not calculated
Target vessel revascularisation 9 165/2050 (8.0) 352/2070 (17.0) 0.5 (0.4 to 0.6) 11 (9 to 14)
Major adverse cardiac event 8 258/1940 (13.3) 440/1958 (22.5) 0.6 (0.5 to 0.7) 11 (9 to 15)

Target vessel revascularisation (Figure 1) was needed about half as often with stents (8%) as with balloon angioplasty (17%). For every eleven patients treated with a stent rather than balloon angioplasty, one fewer needed a revascularisation procedure.

Figure 1: Target vessel revascularisation needed with stents and PTCA in randomised trials



Major adverse cardiac events, including death, revascularisation, disabling stroke and target vessel revascularisation (Table 1), occurred about half as often with stents (13%) as with balloon angioplasty (23%). For every eleven patients treated with a stent rather than balloon angioplasty, one fewer had a major adverse cardiac event.

Comment


This review packs an awful lot into very few pages, and one result is that we know precious little about the patients themselves, making it difficult to know whether they were like any patients we might treat. The low death and reinfarction rates suggest that they were at relatively low risk. We do know they were mostly without cardiogenic shock and with cardiac anatomy suitable for stenting. Also, five trials have yet to be published in full, but contained over half of the patient information.

So these results need to be treated with a degree of caution. Even so, they represent what might be an important result for anyone designing or running a cardiac service. The lower rates of target vessel revascularisation and major adverse cardiac events, affecting about 10% of patients, suggest that stents might be a useful treatment, despite likely higher initial costs. Whether lower reinfarction or mortality might be found in patients at higher risk remains unknown.

References:

  1. MM Zhu et al. Primary stent implantation compared with primary balloon angioplasty for acute myocardial infarction: a meta-analysis of randomized clinical trials. American Journal of Cardiology 2001 88: 297-301.
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