- Design
- Post hoc subgroup analysis of the randomised TARGET trial (NCT03901326)
- Population
- 1,216 patients with 30-90% coronary stenosis on CCTA, randomised to onsite CT-FFR-guided care or standard care
- Primary outcome
- Invasive angiography without obstructive CAD, or no intervention despite obstructive CAD, within 90 days; MACE at 2 years as secondary
- Effect
- 2-year MACE in women, adjusted HR 0.48 (95% CI 0.27-0.87, p=0.015); in men, adjusted HR 0.89 (0.59-1.33, p=0.574); no significant sex-by-treatment interaction
The argument for CT-FFR is that adding physiology to anatomy stops patients being sent for invasive angiography that finds nothing to treat. This post hoc subanalysis of the randomised TARGET trial asked whether that plays out the same way in both sexes.
TARGET randomised 1,216 patients with 30-90% stenosis on coronary CT angiography to onsite CT-FFR-guided care or standard care. The primary endpoint was the proportion undergoing invasive angiography without obstructive disease, or having no intervention despite obstructive disease, within 90 days. Women were older (62.3 ± 8.1 versus 58.2 ± 10.7 years, p<0.001) with comparable anatomical severity.
CT-FFR guidance significantly reduced angiography without obstructive disease and increased early revascularisation in men, but not in women. Over two years, women in the CT-FFR arm had a lower rate of major adverse cardiovascular events (adjusted HR 0.48, 95% CI 0.27-0.87, p=0.015), with no significant difference in men (adjusted HR 0.89, 95% CI 0.59-1.33, p=0.574).
The authors are careful, and the care is the message: there was no statistically significant interaction between sex and treatment strategy, which means the difference between the two hazard ratios could be chance. So what changes today is the first half — CT-FFR earns its place as a gatekeeper to the cath lab. The outcome signal in women is a question for a trial designed to answer it, and reporting it as a reason to image women differently would be running ahead of the evidence.
- Use CT-FFR where the aim is to avoid an angiogram that will find nothing to treat
- Do not offer CT-FFR preferentially to women on the strength of this analysis
- The absence of a significant interaction is the key statistic, not the two separate hazard ratios
- Onsite CT-FFR was what TARGET tested; offsite processing is a different pathway with different delays
- Women in this trial were older with equal anatomical disease — a reminder of the presentation difference, not a result
Why it matters
It is a clean example of why a significant result in one subgroup and a null in another is not a sex difference.
Don't overread it
This was a post hoc subanalysis with no significant sex-by-treatment interaction; the authors label it exploratory.
The statistics, in plain English
When one subgroup shows a significant result and another does not, that alone does not mean the treatment works differently in the two. The test for that is the interaction term, and here it was not significant — so the two hazard ratios, 0.48 and 0.89, are not established as different from each other. This is the most common way subgroup findings mislead, and the trial authors name it themselves.
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