The FLOWER-MI (presented simultaneously at ACC 2021 and NEJM) hit FFR hard. Its outcomes showed that STEMI patients presenting other non-culprit lesions did not benefit from FFR guided revascularization vs PCI.
As it happens with most large studies with unexpected results in the general population, the sub-studies that follow select better samples and, as a result, show different outcomes.
This study focused on the FLOWER-MI arm receiving FFR. It compared one-year outcomes of patients with preserved FFR managed conservatively vs. patients with low FFR undergoing PCI.
Primary end point was a combination of all cause death non-fatal infarction and emergency revascularization at one year.
Of 1,171 patients included in the original study 586 were assessed with FFR. 66% of these patients presented at least one lesion requiring PCI and the remaining 34% showed preserved FFR in all non-culprit lesions and was managed conservatively.
Mean FFR before decision of non-culprit lesions were 0.75±0.10 and 0.88±0.06, respectively.
After a year followup there was a 4.1% events rate in patients undergoing PCI vs nearly a twice as higher rate among patients managed conservatively (8.1%). This difference resulted significative (p=0.02).
Do these results clarify our vision of FFR or do they make it even more blurry? Patients who did not receive PCI because of preserved FFR presented twice as many events. There is plenty of evidence on the safety of deferring lesions using FFR, but this study appears to be an exception.
We could speculate (understanding the value of FFR as a continuum) that deferred patients had values close to the cutoff value.
Read also: ESC 2021 | STEP: Blood Pressure Values in the Elderly, A Never-Ending Debate.
However, this is not the case in this study. Deferred patients had mean FFR 0.88, far from 0.8, putting us at ease.
All in all, there will be more studies following the FLOWER-MI for us to be able to define how to proceed with MI non-culprit lesions.
Conclusion
Patients undergoing ST elevation MI presenting other non-culprit lesions benefit from FFR guided complete revascularization only when receiving PCI to at least one lesion.
Patients with preserved FFR to all non-culprit lesions (and therefore deferred) saw significantly more events at one year.
CIRCINTERVENTIONS-121-011314Original Title: Compared Outcomes of ST-Elevation Myocardial Infarction Patients with Multivessel Disease Treated with Primary Percutaneous Coronary Intervention and Preserved Fractional Flow Reserve of Non-Culprit Lesions Treated Conservatively and of Those with Low Fractional Flow Reserve Managed Invasively: Insights from the FLOWER MI Trial.
Reference: Pierre Denormandie et al. Circ Cardiovasc Interv. 2021 Aug 23. Online ahead of print. doi: 10.1161/CIRCINTERVENTIONS.121.011314.
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