Coronary CT angiography with fractional flow reserve analysis (FFRCT) may be an effective alternative to invasive coronary angiography for suspected coronary artery disease (CAD), according to investigators of the PLATFORM study.
Sixty percent of patients scheduled for invasive testing had their invasive imaging cancelled in part due to FFRCT data. This FFRCT-guided cohort was less likely to have catheterization without obstructive CAD at 90 days (12.4% versus 73.3% in the invasive angiography arm, P<0.0001).
At 1 year, there was no difference in major adverse cardiac events (1.04% versus 1.07%) or the composite of adverse events and vascular complications (3.63% versus 2.14%). Quality of life scores and cumulative radiation exposure (mean 10.7 versus 10.4 mSv, P=0.21) were also even between groups.
The FFRCT-guided arm did stand out as having an advantage in terms of cost, however (mean $8,127 versus $12,145, P<0.0001), reported Pamela S. Douglas, MD, of Duke University Medical Center in Durham, N.C., and colleagues online in the Journal of the American College of Cardiology.
A separate cohort with planned non-invasive testing had FFRCT analyzed for some patients. Rates of catheterization without obstructive CAD at 90 days were not significantly different for this FFRCT subgroup than for their peers who got only CT angiography (12.5% versus 6.0%, P=0.95).
In addition, 1-year rates of major adverse cardiac events (1% versus 0%) were too close to give either group an advantage in clinical outcomes. Costs too were similar between the two arms ($3,049 versus $2,579, P=0.82).
Douglas and colleagues did found, however, that cumulative radiation exposure at 1 year was higher for the FFRCT arm (mean 9.55 mSv versus 6.42 mSv for CT angiography alone, P<0.001). Quality of life scores were largely similar between groups, although the 5-item EuroQOL scale showed greater improvement in the FFRCT group (mean change +0.12 versus +0.07, P=0.02).
René R. Sevag Packard, MD, of UCLA Medical Center, and Ronald P. Karlsberg, MD, of Cedars Sinai Heart Institute in Los Angeles, expressed concern with recommending FFRCT to all patients with suspected CAD.
In an accompanying editorial, they noted the lack of advantage among FFRCT patients in the non-invasive arm: “Costs were higher in the planned noninvasive cohort, even when FFRCT was assigned a cost weight equal to coronary CT angiography, emphasizing that FFRCT should not be universally proposed to patients during CAD work-up but considered in patients designated to invasive coronary angiography.”
The PLATFORM study included two prospective cohorts of a total 584 consecutive patients who had stable, new-onset chest pain and were deemed to have intermediate odds of obstructive CAD, divided into those with a planned noninvasive test or planned invasive angiography. Those two groups were further subdivided into sequential cohorts.
In the initial period, for the two cohorts respectively, patients got usual care testing — invasive or not, as planned by their local clinicians — or the planned standard invasive coronary angiography. In the second period, both cohorts got FFRCT instead of planned testing.
The authors acknowledged their small sample size and the relatively brief follow-up duration, one too short to detect an impact on clinical outcomes.
Packard and Karlsberg added that “the following caveats should be noted: the study was conducted in European centers and reflects local practice patterns, which cannot be assumed to be identical to American centers. Moreover, as the PLATFORM trial was not a randomized trial, the decision to medically manage or directly send patients to the cardiac catheterization laboratory must be examined more closely.”
“The study was underpowered to test whether this decrease in invasive coronary angiography led to significant differences in ‘hard’ cardiovascular events such as fatal myocardial infarction, acute coronary syndromes, or urgent revascularizations,” the editorialists also noted. What’s more, “FFRCT values were available in only 58% of noninvasive and 60% of invasive arm cases, respectively, for clinical decision making.”
The duo commented that their experience with FFRCT has not been easy, rattling off obstacles, such as the lack of insurance reimbursement and concern about relying on this modality alone.
Nonetheless, they acknowledged the advantage to FFRCT “in what remains an Achilles’ heel of coronary CT angiography: decreased accuracy in the setting of significant calcification.”
“For FFRCT to gain broader use, outcomes trials similar to the FAME trials should be performed to unequivocally demonstrate the central role this technology can play in managing patients with CAD,” they suggested.
“Currently, FFRCT is only being used as a ‘surrogate’ to invasive FFR. We should not assume this surrogate measure has the same outcome associations as invasive FFR until these measures meet the same standards in similarly designed rigorous trials.”
The PLATFORM study was funded by Heartflow.
Douglas reported receiving grants from HeartFlow during the conduct of the study; and has previously received other support from GE Medical Systems.
Journal of the American College of Cardiology
Douglas PS, et al “1-year outcomes of FFRCT-guided care in patients with suspected coronary disease: the PLATFORM study” J Am Coll Cardiol 2016; DOI: 10.1016/j.jacc.2016.05.057.
Journal of the American College of Cardiology
Packard RRS, et al “Integrating FFRCT into routine clinical practice: a solid PLATFORM or slippery slope?” J Am Coll Cardiol 2016; DOI: 10.1016/j.jacc.2016.05.056.