FLOWER-MI: No Benefit to FFR-Guided PCI versus Angiography-Guided Procedure

Etienne Puymirat, MD

Results of the FLOWER-MI study suggest a fractional flow reserve (FFR)-guided approach to revascularization provided no benefit over an angiography-guided strategy in patients with STEMI who have multivessel disease.

Presented at the American College of Cardiology’s 70th Annual Scientific Session (ACC.21), results of the study demonstrate an FFR-guided strategy provided no benefit in terms of risk of death, myocardial infarction, or urgent revascularization at 1 year and a secondary cost analysis suggested this strategy was also more expensive.

“The strategy of using FFR to guide the stenting procedure is not superior to the standard technique of using angiography to treat additional partially blocked arteries,” said lead investigator Etienne Puymirat, MD, professor of cardiology at the University of Paris, director of intensive care at the Georges Pompidou Hospital in Paris, in a statement. “In addition to having no benefit, we have also shown that, based on costs in France, the FFR-guided strategy is more expensive.”

With some data suggesting an FFR-guided approach resulted in a lower frequency of revascularization, the Flow Evaluation to Guide Revascularization in Multivessel ST-Elevation Myocardial Infarction (FLOWER-MI) trial was designed to assess whether use of FFR resulted in better clinical outcomes than use of angiography for complete revascularization of patients with STEMI and multivessel disease. Conducted from December 18, 2016-December 6, 2018, FLOWER-MI was designed as a randomized, open-label, multicenter trial with blinded endpoint evaluation and randomized 1171 patients from 41 sites in France to angiography-guided or FFR-guided PCI.

For inclusion in the study, patients had to be at least 18 years of age with STEMI and had undergone successful PCI of an infarct-related artery. Exclusion criteria included hemodynamic instability, previous CABG, coronary artery calcification or chronic total occlusion, and referral for CABG. In total, 581 were assigned to angiography-guided PCI and 590 were assigned to FFR-guided PCI. Of these, 577 in the angiography group and 586 in the FFR group were included in the final analysis.

For the primary outcome of the trial, investigators chose a composite endpoint consisting of death from any cause, nonfatal myocardial infarction, or unplanned hospitalization leading to urgent revascularization at 1 year. Investigators also planned to assess multiple secondary outcomes including individual components of the primary outcome. Investigators pointed out that while complete revascularization during the initial procedure was encouraged, all patients underwent complete revascularization before discharge from the hospital and within 5 days of the initial procedure.

No major differences were noted between either study arm. The mean age of the overall population 62.2±11.1 years, the mean number of lesions in the infarct-related artery was 1.2±0.5 (median, 1; IQR, 1-1), and drug-eluting stents were used in 99% of patients. The mean number of stents used per patient for nonculprit lesions was 1.01±0.99 in the FFR-guided group and 1.50±0.86 in the angiography-guided group.

At 1 year, a primary outcome event had occurred among 32 of 586 patients in the FFR-guided group and 24 of 577 in the angiography-guided group (HR, 1.32; 95% CI, 0.78-2.23; P=.31). When assessing secondary outcomes at 1 year, investigators found 9 patients in the FFR group and 10 patients in the angiography group had died, nonfatal reinfarction occurred in 18 FFR-guided patients compared to 10 angiography-guided patients (HR, 1.77; 95% CI, 0.82-3.84), and unplanned hospitalization leading to urgent revascularization was needed in 15 FFR-guided patients compared to 11 angiography-guided patients (HR, 1.34; 95% CI, 0.62-2.92).

In the aforementioned statement, Puymirat noted the overall rate of cardiovascular events in both groups was lower than they had expected.

“These patients were at high cardiovascular risk because of having multi-vessel disease,” Puymirat said. “Using data from previous trials and registries in this population, we estimated that about 15% of patients would have an adverse event within one year, but in our study the rate was 5% at one year.”

This study, “Multivessel PCI Guided by FFR or Angiography for Myocardial Infarction,” was presented at ACC.21 and simultaneously published in the New England Journal of Medicine.