SAN FRANCISCO – Estimating fractional flow reserve with computed tomography appears to reduce resource use and costs when compared with invasive coronary angiography in stable patients with possible symptoms of coronary disease, according to a substudy of the prospective, multicenter PLATFORM trial.
Fractional flow reserve estimated by CT (FFR-CT) was also associated with greater improvement in quality of life measures during the 90-day study period, when compared with usual noninvasive testing, Dr. Mark A. Hlatky of Stanford (Calif.) University reported at the Transcatheter Cardiovascular Therapeutics annual meeting.
Sharon Worcester/Frontline Medical News
Dr. Mark A. Hlatky
The PLATFORM trial and substudy data are “game changers,” according to the discussant, Dr. Bernard de Bruyne of Cardiovascular Center Aalst, Belgium, who predicted that if the findings are confirmed in other studies, “this kind of approach will probably largely replace the presently available noninvasive approaches and noninvasive stress testing.”
To assess the effect of using FFR-CT rather than usual care on cost and quality of life, patients with stable symptoms, intermediate probability of CAD (the pretest CAD probability was 49%), and no established CAD diagnosis were enrolled into one of two strata based on whether invasive or noninvasive diagnostic testing was planned. Among 193 patients in the planned invasive testing group who underwent FFR-CT, costs were reduced by 32%, compared with 187 patients in the group who received usual care ($7,343 vs. $10,734). The difference was highly statistically significant.
Among 104 patients in the planned noninvasive testing group who underwent FFR-CT, costs did not differ significantly, compared with 100 in that group who received usual care ($2,679 vs. $2,137), Dr. Hlatky reported at the meeting, which was sponsored by the Cardiovascular Research Foundation.
These findings persisted after propensity score matching, he noted.
Furthermore, scores on each of three quality of life measures improved in the overall study population, and scores in the noninvasive stratum improved more with FFR-CT than with usual care. For example, Seattle Angina Questionnaire scores were 19.5 vs. 11.4, EuroQOL scores were 0.08 vs. 0.03, and visual analog scale scores were 4.1 vs. 2.3 in the groups, respectively. The improvements in the invasive cohort were similar with FFR-CT and usual care, Dr. Hlatky noted.
The findings, published simultaneously online (J Am Coll Cardiol. 2015. doi:10.1016/j.jacc.2015.09.051), suggest that the combination of anatomic and functional data provided by an FFR-CT–guided testing strategy may lead to more selective use of invasive procedures than relying solely on the anatomic data provided by invasive coronary angiography, Dr. Hlatky reported.
He explained that FFR, which assesses the functional significance of individual coronary lesions, can be estimated noninvasively from standardly acquired CT data based on computational fluid dynamics. FFR-CT was recently approved for clinical use by the Food and Drug Administration and the European Medicines Agency based on its diagnostic accuracy, he said.
The clinical effectiveness of the strategy was demonstrated in the PLATFORM trial which showed a reduction in the rate of invasive angiography without obstructive coronary artery disease from 73% to 12% with the use of FFR-CT. The current findings further demonstrate that the approach improves quality of life outcomes.
Though limited by the use of a consecutive observational design, as opposed to a randomized trial design, the large effect sizes suggest that findings would be similar in a randomized study, Dr. Hlatky said.
“I don’t think this is by chance. The plausibility of it has been explained,” he said, adding that while most people are happy with a normal CT angiography because of the high sensitivity, estimated FFR using the CT technique can be helpful in the setting of uncertainty.
“If you see something and you’re not sure if it’s significant, and if the estimated FFR from this technique is normal, that’s extremely reassuring that it’s just something you’re seeing but it’s not necessarily obstructing flow,” he said.
He added that “this would be best tested by doing a real, true, randomized study,” but said he considers the findings to be “quite interesting and completely in line with the clinical results.”
The technique is “entering progressively into practice in Europe,” said Dr. de Bruyne, who is a PLATFORM coinvestigator. “It is already used in clinical practice. You get the anatomy and physiology at the same time and same place. It is a really important paradigm change,” he said.
Dr. Hlatky and Dr. de Bruyne reported receiving research grants from HeartFlow, which supported the study.