No benefit to FFR-guided PCI over angiographic-guided PCI of Nonculprit Lesions after STEMI: Results from FLOWER-MI Show

Key Points:

• While FFR-guided PCI is superior in chronic coronary syndrome, its role in primary PCI of acute coronary syndrome remained unknown.
• Patients with STEMI and multivessel disease, were randomized to undergo FFR-guided PCI versus angiography-guided PCI of non-culprit lesions after treatment of the culprit.
• There was no difference in MACE at one year between the two intervention arms at one year.

Background: The COMPLETE trial showed that in patients presenting with STEMI and multivessel disease, complete revascularization of non-culprit lesions was associated with favorable outcomes. While Fractional Flow Reserve (FFR) has been validated in stable coronary disease, its role in the treatment of non-culprit vessels in acute coronary syndrome is yet to be evaluated.

The FLOWER-MI study hoped to assess the role of FFR-guided PCI of such vessels. In a late-breaking clinical trial session at the 2021 American College of Cardiology Scientific Sessions meeting today, Dr. Etienne Puymirat of Paris, France presented the results of their study. In the trial, STEMI patients who underwent treatment of their culprit lesion and found to have at least 50% stenosis in one other vessel, were randomized in a 1:1 fashion to receive complete revascularization via either an angiographic-guided or FFR-guided PCI approach. Revascularization occurred within the index hospitalization. Patients with cardiogenic shock, prior coronary artery bypass surgery, chronic total occlusions were among those excluded from the trial.

1141 patients across 41 centers in France were randomized to either arm. The population was mostly male (>80%) with a mean age of 62 years and a mean LVEF of 50%. Almost half of the patients were treated for a right coronary artery STEMI and returning for PCI of the left anterior descending artery. Almost all patients received second-generation drug eluting stents.

Results

At one year there was no difference in MACE-free survival between the two arms. In fact, FFR-guided PCI had a no significant increase in MACE compared to angio-guided PCI (HR 1.32, 95% CI 0.78-2.23, p = 0.31). There was also no significant difference in the pre-specified secondary outcomes of stent thrombosis, any revascularization, hospitalization for heart failure, or hospitalization for recurrent ischemia. The authors went one step further to perform a cost-effectiveness analysis, finding FFR-guided strategy to have a significant higher cost, favoring angiography-guided PCI.

“While I am a huge proponent of the use of physiology, I’m not very surprised by these data,” said Dr. Marie-France Poulin, Assistant Director of Structural Interventions at Beth Israel Deaconess Medical Center in an interview with CardiologyNowNews. “The event rates were so low that a difference would have been hard to detect. What is interesting is that the curves start to separate at 7 months, so I would be interested to see what happens with longer-term follow-up. Overall the authors should be congratulated on a very well-designed study in an area that requires more study.” When asked whether she would alter her current practice, Dr. Poulin stated that it is too soon to do so, but she looks forward to future studies in this space to inform her decision.