CT-derived FFR predicts infarction and death beyond what the stenosis looks like

Design

nationwide observational cohort, 27 sites, 3-year follow-up

Population

7,836 patients with stable coronary disease undergoing CT angiography with clinically indicated FFR-CT, 2017-2020

Primary outcome

myocardial infarction, cardiovascular death, all-cause death and revascularisation, analysed individually

Effect

stenosis-specific FFR-CT ≤0.7 adjusted HR 2.94-3.39 for MI; ≤0.5 adjusted HR 2.92 for cardiovascular death; 1.5% 3-year event rate when normal

Patients having coronary CT angiography with clinically indicated FFR-CT analysis at 27 English sites between 2017 and 2020 were followed for three years — 7,836 patients, median age 63, 37.4% women. Lower FFR-CT values tracked stepwise with worse outcomes across myocardial infarction, cardiovascular death, all-cause death and revascularisation. After adjustment for risk factors and for CAD-RADS stenosis severity, stenosis-specific FFR-CT at or below 0.7 remained associated with infarction (adjusted HR 2.94-3.39), and at or below 0.5 with cardiovascular death (adjusted HR 2.92) and all-cause death (adjusted HR 1.49). The optimal threshold for future events fell at 0.67 rather than the familiar 0.8.

The number worth carrying is the other end. Where stenosis-specific FFR-CT was normal, the three-year rate of infarction or cardiovascular death was 1.5%. That is a reassurance figure you can give a patient in clinic, and it is the part of this study most likely to be used.

Stenosis-specific and distal-vessel measurements disagreed in 36.4% of patients, which is a reminder that FFR-CT is not one number per patient. Where a report gives both, they are answering different questions, and the stenosis-specific value is the one these outcome data attach to. Against that, adding FFR-CT to risk factors and stenosis severity moved the C index by 0.012 — statistically clear in a cohort this size, but a small gain in discrimination, and not an argument for the test where anatomy already answers the question.

• Use the 1.5% three-year event rate to reassure patients with a normal stenosis-specific FFR-CT.
• Read the stenosis-specific value, not the distal one, when using FFR-CT for prognosis.
• Treat 0.67 as the value that flags high risk, while 0.8 remains the diagnostic cutoff.
• Check whether a report gives both measurements before quoting a number to a patient — they disagree in about a third.
• Availability and cost put FFR-CT out of reach in much of Indian practice; the finding does not change how to act on a CT angiogram alone.

Why it matters

A reassuring number after CT angiography is the thing clinics most often lack, and this gives one with a denominator behind it.

Don't overread it

Association, not causation — nobody was randomised to having FFR-CT, and a low value has not been shown to be worth acting on.

The statistics, in plain English

This is an observational cohort, so a low FFR-CT marks a patient at higher risk rather than showing that acting on the number improves anything. The hazard ratio ranges quoted reflect different comparison bands, not uncertainty. The change in C index of 0.012 is the honest measure of what FFR-CT adds once risk factors and stenosis severity are known: real, given P < 0.001 in 7,836 patients, but small.

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