The clinical utility of FFR_CT stratified by age

Background: CT coronary angiography (CTA) with Fractional Flow Reserve as determined by CT (FFR_CT) is a safe alternative to invasive coronary angiography. A negative FFR_CT has been shown to have low cardiac event rates compared to those with a positive FFR_CT. However, the clinical utility of FFR_CT according to age is not known.

Methods: Patients' in the ADVANCE (Assessing Diagnostic Value of Non-invasive FFRCT in Coronary Care) registry, were stratified into those ≥65 or <65 years of age. The impact of FFR_CT on clinical decision-making, as assessed by patient age, was determined by evaluating patient management using CTA results alone, followed by site investigators submitting a report on the treatment plan based upon the newly provided FFR_CT data. Outcomes at 1-year post CTA were assessed, including major adverse cardiovascular events (myocardial infarction, all-cause mortality or unplanned hospitalization for ACS leading to revascularisation) and total revascularisation. Positive FFR_CT was deemed to be ​≤ ​0.8.

Results: FFR_CT was calculated in 1849 (40.6%) subjects aged <65 and 2704 (59.4%) ​≥ ​65 years of age. Subjects ≥65 years were more likely to have anatomic obstructive disease on CTA (≥50% stenosis), compared to those aged <65 (69.7% and 73.2% respectively, p ​= ​0.008). There was a similar graded increase in recommended and actual revascularisation with either CABG or PCI, with declining FFR_CT strata for subjects above and below the age of 65. MACE and revascularisation rates were not significantly different for those ​≥ ​or <65, regardless of FFR_CT positivity or stenosis severity <50% or ≥50%. With a negative FFR_CT result, and anatomical stenosis ≥50%, those ​≥ ​and <65 years of age, had similar rates of MACE (0.2% for both, p ​= ​0.1) and revascularisation (8.7% and 10.4% respectively p ​= ​0.4). Logistic regression analysis, with age as a continuous variable, and adjustment for Diamond Forrester Risk, baseline FFR_CT and treatment (CABG, PCI, medical therapy), indicated a statistically significant, but small increase in the odds of a MACE event with increasing age (OR 1.04, 95% CI 1.006-1.08, p ​= ​0.02). Amongst patients with a FFR_CT > 0.80, there was no effect of age on the odds of revascularisation.

Conclusion: The findings of this study point to a low risk of MACE events or need for revascularisation in those aged ​≥ ​or <65 with a FFR_CT>0.80, despite the higher incidence of anatomic obstructive CAD in those ≥65 years. The findings show the clinical usefulness and outcomes of FFR_CT are largely constant regardless of age.