Design: international, randomised, open-label trial (AIR-STEMI)
Population: 1,823 patients with STEMI and multivessel disease after successful culprit treatment, median age 66, 24% women
Primary outcome: composite of death, myocardial infarction, stroke or TIA, or ischaemia-driven revascularisation
Effect: 8.9% vs 13.7%, hazard ratio 0.62 (95% CI 0.47–0.83), p<0.001

Complete revascularisation is already recommended after successful treatment of the culprit lesion in ST-elevation myocardial infarction with multivessel disease. What has been unsettled is how to decide which non-culprit lesions to treat. AIR-STEMI randomised 1,823 such patients — median age 66, 24% women — to complete revascularisation guided by functional coronary angiography, meaning physiological assessment of each lesion, or by conventional angiographic appearance.

At a median 17.9 months, the composite of death from any cause, myocardial infarction, stroke or transient ischaemic attack, or ischaemia-driven revascularisation occurred in 81 of 913 physiology-guided patients (8.9%) against 125 of 910 angiography-guided patients (13.7%) — hazard ratio 0.62 (95% CI 0.47 to 0.83, p<0.001). The safety composite of contrast-associated acute kidney injury or major bleeding also favoured physiology: 4.6% against 7.1%, hazard ratio 0.63 (0.43 to 0.93, p=0.02).

That second result is the one that should move a service. Physiological guidance is often resisted on the grounds that it adds time, contrast and cost to a patient who has just had an infarct. Here it reduced the harms that argument is built on, presumably by identifying lesions that did not need treating at all. For a unit that already stocks pressure wires for stable disease, the change is procedural rather than capital: use them for the non-culprit lesions too.

Apply this to non-culprit lesions after the culprit has been successfully treated, not to the culprit itself
Expect fewer lesions to be stented, which is where the contrast and bleeding reduction comes from
Audit how many non-culprit lesions your unit currently treats on appearance alone
Record the physiological index used for each non-culprit lesion so the decision is traceable
Do not read this as licence to defer complete revascularisation — both arms were revascularised

Why it matters

The usual objection to physiology in the acute setting is that it adds risk; this trial found the opposite.

The statistics, in plain English

A hazard ratio of 0.62 with an interval of 0.47 to 0.83 means the physiology-guided strategy reduced the rate of the composite outcome by a little under 40%, and the interval stays clear of 1.0 throughout. The absolute figures are the more useful ones for consent: 13.7% down to 8.9%, so roughly one fewer event for every 21 patients managed this way over about 18 months. Because the primary outcome is a composite, check which component moved — ischaemia-driven revascularisation usually contributes most, and it is the softest of the four.