FLOWER-MI Shows No Benefit of FFR-Guided PCI in STEMI Patients With Multivessel Disease

May 16, 2021—The FLOWER-MI trial evaluated the use of fractional flow reserve (FFR) in guiding stent placement during percutaneous coronary interventions to determine if a second stenting procedure is needed in patients with multivessel disease experiencing an ST-segment elevated myocardial infarction (STEMI). The French study found that use of FFR did not improve outcomes and was more costly than using angiography alone to guide the procedure.

“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,” commented Principal Investigator Etienne Puymirat, MD, in a press release from the American College of Cardiology (ACC). “In addition to having no benefit, we have also shown that, based on costs in France, the FFR-guided strategy is more expensive.”

Dr. Puymirat, who is professor of cardiology at the University of Paris, director of intensive care at the Georges Pompidou Hospital in Paris, France, presented the findings virtually at the ACC’s 70th annual scientific session. The study was simultaneously published online by Dr. Puymirat et al in The New England Journal of Medicine.

According to ACC, the FLOWER MI trial is the first study to perform a head-to-head comparison of outcomes in STEMI patients with multivessel disease who underwent either FFR-guided stenting or stenting guided by angiography alone. Previous studies have shown that STEMI patients treated with FFR-guided stenting had better outcomes than those treated with medication alone, without the insertion of a stent.

FLOWER-MI, which was conducted at 41 centers in France, enrolled 1,171 patients who had a received a stent after experiencing a STEMI and who also had a second coronary artery that was at least 50% blocked.

The patients’ average age was 62 years and 83% were men. Immediately after their first stenting procedure, all patients were randomly assigned to undergo a second stenting procedure in the partially blocked artery, guided either by FFR or by angiography alone. The second procedure was performed within 5 days of the first during the same hospitalization.

As summarized in the ACC press release, the investigators found that at 12 months 5.5% of patients in the FFR-guided group had died, had another nonfatal heart attack, or had undergone an additional stenting procedure, compared with 4.2% of those in the angiography-guided group, not a statistically significant difference. Moreover, the FFR-guided procedure was more expensive than the procedure guided by angiography alone.

The incidence of major adverse cardiovascular events in both groups of patients was considerably lower than investigators expected, noted Dr. Puymirat in the ACC announcement. He stated, “These patients were at high cardiovascular risk because of having multivessel disease. Using data from previous trials and registries in this population, we estimated that about 15% of patients would have an adverse event within 1 year, but in our study the rate was 5% at 1 year.”

The study failed to meet its primary endpoint, a composite of death from any cause, nonfatal heart attack, or urgent need for an additional stenting procedure within 12 months.

A secondary endpoint looking at cost-effectiveness favored the use of angiography alone. However, the cost-effectiveness analysis was based on the costs of the two treatment approaches in France and might not be applicable in other countries, advised Dr. Puymirat.

The FLOWER-MI investigators will continue to follow the patients in the study for another 2 years, noted the ACC press release.