FFR strategy may not top angiography strategy in STEMI, complete revascularization
Among patients with STEMI who underwent complete revascularization, a fractional flow reserve-guided strategy did not improve outcomes compared with an angiography-guided strategy, according to results of the FLOWER-MI trial.
The researchers randomly assigned 1,171 patients (mean age, 62 years; 83% men) who had STEMI and multivessel disease and underwent successful PCI of the culprit artery to receive an FFR-guided or angiography-guided strategy for complete revascularization. Etienne Puymirat, MD, PhD, professor of cardiology at the University of Paris and director of the cardiology ICU at Georges Pompidou European Hospital, presented the results, which were simultaneously published in The New England Journal of Medicine, at the American College of Cardiology Scientific Session.
Previous studies determined that FFR-guided PCI is superior to angiography-guided PCI in patients with chronic coronary syndromes, and that FFR-guided and angiography-guided strategies for complete revascularization are superior to a culprit-lesion-only treatment strategy in patients with STEMI and multivessel disease, but FLOWER-MI was needed “to determine whether FFR-guided complete revascularization translates into better clinical outcomes compared with angiography-guided complete revascularization in STEMI patients with multivessel disease,” Puymirat said during his presentation.
Operators opted for staged procedures in 96% of both groups, he said.
In the angiography-guided group, the mean number of stents placed in nonculprit lesions was 1.5, whereas in the FFR-guided group, it was 1.01, according to the researchers.
The primary outcome of all-cause death, nonfatal MI or unplanned hospitalization leading to urgent revascularization at 1 year occurred in 5.5% of patients in the FFR group compared with 4.2% of those in the angiography group (HR = 1.32; 95% CI, 0.78-2.23; P = .31), Puymirat said during his presentation.
There were also no differences in all-cause death (FFR, 1.5%; angiography, 1.7%; HR = 0.89; 95% CI, 0.36-2.2), nonfatal MI (FFR, 3.1%; angiography, 1.7%; HR = 1.77; 95% CI, 0.82-3.84) or unplanned hospitalization leading to urgent revascularization (FFR, 2.6%; angiography, 1.9%; HR = 1.34; 95% CI, 0.62-2.92) at 1 year, according to the researchers.
At 1 year, Puymirat said, there were no differences between the groups in stent thrombosis, any revascularization, hospitalization for HF, recurrent ischemia, hospitalization for recurrent ischemia, quality-adjusted life-years or number of anti-anginal medications used, but the FFR group had a higher rate of any CV-related hospitalization (11.6% vs. 8%; HR = 1.49; 95% CI, 1.03-2.17).
Adjusted costs at 1 year were higher in the FFR group than in the angiography group (P < .01), Puymirat said, noting all patients were treated in France.
“In patients presenting with STEMI and multivessel disease ... the event rate at 1 year is very low,” he said. “FFR-guided PCI of non-infarct-related lesions does not reduce the risk of the composite outcome ... compared with angiography-guided PCI.”
In a discussion after the presentation, William Fearon, MD, professor of medicine and director of interventional cardiology at Stanford University School of Medicine and chief of the cardiology section at the VA Palo Alto Health Care System, questioned whether the study was underpowered.
“Both groups of patients suffered a STEMI treated with primary PCI, which is likely the most important predictor of future adverse events,” he said. “We wouldn’t expect any difference between the two groups from this. In the FFR group, 55% had a nonculprit lesion that was positive, and 66% actually had PCI of a nonculprit lesion, meaning that all of these patients were treated in a similar fashion to the angio-guided patients. Therefore, we wouldn’t expect any difference in outcomes in those, either. This means that only about one-third of the FFR-guided patients, or about 200 patients, did not receive nonculprit PCI, and therefore only in this small group could we expect a difference in outcomes from the angio-guided group. In addition, it sounds like you expected almost a twofold higher event rate with the angio-guided group, with 15% compared to 9.5% ... making me wonder whether this was a little overly optimistic.”
Puymirat said the study was designed in 2015 based on the event rates from data available at that time.
Reference:
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We know that after acute MI, it is best to try to revascularize not only the artery that caused the MI, but also the other arteries that are severely stenosed. However, the determination of which arteries should be treated, and the timing of the treatment, has continued to be debated. It appeared using FFR would be the best way to determine which nonculprit arteries would need treatment.
FLOWER-MI is interesting because patients for whom angiography determined which of their arteries should be treated did just as well as patients for whom FFR made that determination. That broadens the population that can be treated and perhaps even the timing of when these arteries can be treated after MI. These determinations can now be made in centers that do not have FFR technology — though it is now pretty widely distributed in Western Europe and the United States — and the timing can be more flexible if an additional technology is not required.
However, the investigators included a disclaimer that the confidence intervals were so wide that one should not draw conclusions, and further study needs to be done. Nonetheless, this is one of the first studies suggesting angiography alone is sufficient to determine which arteries need to be treated and which do not. That may be controversial because other studies have shown that FFR is the gold standard for determining which arteries need to be treated. A benefit of FFR is that it is binary; it produces a number and does not require reliance on a subjective opinion. I would think there will be further study on this topic.
Of note, in patients with non-ST-segment elevation ACS, FFR has been determined to be superior to angiography alone to decide which arteries need to be treated. These results ought to stimulate further debate.
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Puymirat E, et al. Joint American College of Cardiology/New England Journal of Medicine Late-Breaking Clinical Trials. Presented at: American College of Cardiology Scientific Session; May 15-17, 2021 (virtual meeting).