Complete revascularisation after STEMI is already recommended. What has not been settled is how to choose the non-culprit lesions. AIR-STEMI randomised 1,823 patients with STEMI and multivessel disease, after successful culprit treatment, to complete revascularisation guided by functional coronary angiography or by conventional angiography alone. Median age was 66, and 24% were women.
At a median 17.9 months, the primary composite of death, myocardial infarction, stroke or transient ischaemic attack, or ischaemia-driven revascularisation occurred in 81 patients (8.9%) in the physiology-guided arm and 125 (13.7%) in the angiography-guided arm, hazard ratio 0.62 (95% CI 0.47 to 0.83, p<0.001).
The safety result is the one that closes the argument. Contrast-associated acute kidney injury or major bleeding occurred in 4.6% of the physiology-guided group versus 7.1% of the angiography-guided group, hazard ratio 0.63 (95% CI 0.43 to 0.93, p=0.02). The usual objection to a physiological assessment — extra time, extra contrast, extra risk in an acute setting — went the other way. Judging lesions by physiology rather than by appearance meant fewer of them were treated, and fewer procedures means less contrast and less access-site bleeding.
For a catheter laboratory that already runs functional angiography, this is straightforward. For one that does not, it is an argument for acquiring it, and the resource argument is favourable: it reduces the number of stents deployed. In an Indian setting where stent cost is often paid out of pocket, a strategy that treats fewer lesions with better outcomes is worth the capital investment in software.
- Assess non-culprit lesions after STEMI by functional angiography rather than by visual stenosis severity
- Expect to stent fewer lesions, not more — the benefit came partly from avoiding unnecessary intervention
- Anticipate less contrast nephropathy and less major bleeding, not more, from the added assessment
- Do not extrapolate to the culprit lesion itself, which was treated conventionally in all patients before randomisation
- Where functional angiography is unavailable, this strengthens the case for pressure-wire physiology rather than eyeballing the angiogram
The statistics, in plain English
Both the efficacy and the safety confidence intervals sit entirely below 1.0, which is unusual and important: normally a more effective strategy carries some safety cost, and the trade-off has to be argued. Here there is none to argue. The absolute difference on the primary endpoint is 4.8 percentage points over about 18 months, so roughly 21 patients need treating by this strategy rather than the other to prevent one event — a low number for a change that costs no additional hardware.
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