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PLATFORM: FFR-CT reduces unnecessary invasive catheterization in patients with suspected CAD
LONDON — Patients with suspected CAD planned for invasive catheterization were less likely to undergo an unnecessary procedure if their diagnosis was guided by CTA and CT-derived fractional flow reserve, according to the results of the PLATFORM study.
Researchers investigated whether use of CT-derived fractional flow reserve (FFR-CT) would enable clinicians to safely and effectively lower their rate of performing cardiac catheterizations in patients without obstructive CAD. The results were simultaneously presented at the European Society of Cardiology Congress and published in the European Heart Journal.
Pamela S. Douglas
Pamela S. Douglas, MD, MACC, FASE, FAHA, and colleagues prospectively assigned 584 patients with new-onset stable chest pain (mean age, 60.9 years; 40% women; mean pretest CAD probability, 49%) to receive the usual testing or CTA/FFR-CT; FFR-CT was performed via a central analysis (HeartFlow). They further separated the patients into two cohorts: those who would undergo invasive coronary angiography according to usual care and those who would receive a standard noninvasive test.
All patients assigned CTA/FFR-CT underwent CTA. If the CTA revealed stenosis of at least 30% or the patient was referred to invasive coronary angiography, investigators were to request FFR-CT, Douglas, from Duke University Clinical Research Institute and Duke University School of Medicine, said at a press conference.
The primary outcome was the percentage of patients who underwent invasive catheterization despite not having obstructive CAD, defined as not having stenosis of 50% or higher or FFR of 0.8 or lower, at 90 days. Secondary outcomes included MACE (defined as death, MI or unstable angina) and radiation exposure. Researchers also collected data on cost and quality of life; those will be published and presented at a later date, Douglas said at the press conference.
Among patients with planned invasive coronary angiography, 12.4% in the FFR-CT arm and 73.3% in the usual care arm had the procedure despite the absence of obstructive CAD (risk difference, 60.8%; 95% CI, 53-68.7; P < .0001), Douglas said. In fact, she noted, 61% of the FFRCT group had their invasive coronary angiography cancelled following the FFR-CT results.
Radiation exposure did not differ between the groups (FFR-CT, 9.9 mSv; usual care, 9.4 mSv; P = .2), and rates of revascularization were similar, though FFR-CT doubled the availability of functional data at the time of PCI or CABG, she said.
Among those with planned noninvasive testing, 12.5% of the FFR-CT arm and 6% of the usual care arm underwent invasive coronary angiography despite the absence of obstructive CAD (P = .95), though Douglas noted that these were low-risk patients. Mean radiation exposure was higher in the FFRCT arm (8.8 mSv vs. 5.8 mSv; P = .0002), the researchers found.
Only two reports of MACE occurred, both in the FFR-CT arm of the group with planned invasive testing, Douglas said. The rate of MACE or vascular complications among those with planned invasive testing was 3.6% in the FFR-CT arm and 1.1% in the usual care arm. Among those with planned noninvasive testing, the rate was 1% in the FFR-CT arm and 0% in the usual care arm.
“Use of a combined noninvasive anatomic and functional strategy employing [FFR-CT] was safe and improved patient selection for invasive catheterization,” Douglas said. – by Erik Swain
References:
Douglas PS, et al. Hot Line VI: Coronary Artery Disease. Presented at: European Society of Cardiology Congress; Aug. 29-Sept. 2; London.
Douglas PS, et al. Eur Heart J. 2015;doi:10.1093/eurheartj/ehv444.
Disclosures: The study was funded by HeartFlow. Douglas reports receiving grants from HeartFlow and other support from GE Medical Systems.
Perspective
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We are still looking for ways to combine anatomical and functional testing into practice. We are still looking for more data on downstream effect, and we have to see what the costs are; we don’t know those yet. Because of that, right now, I think it’s a little too early for the FFR-CT approach to have an impact. Once we know the costs, we will have to compare them with other noninvasive functional tests. There will probably be some place for it, but we will have to assess that in the context of other noninvasive exams. We have to do more studies.
Perspective
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PLATFORM was an interesting nonrandomized study examining the potential utility FFR-CT in patients with chest pain intended for invasive catheterization. It suggests that one might be able to use this noninvasive test to avoid many unnecessary coronary angiograms that will demonstrate nonobstructive CAD, while still being able to detect an equivalent number of patients with obstructive CAD who need revascularization. This sets the stage for a randomized clinical trial powered for outcomes as well as for reduced procedures and costs.