FFR-based PCI deferral risky in non-ST-segment elevation ACS patients
medwireNews: Research suggests that patients with non-ST-segment elevation acute coronary syndromes (NTSE-ACS) may be at high risk of cardiovascular events even if they meet the fractional flow reserve (FFR) cutoff for delaying percutaneous coronary intervention (PCI).
The retrospective analysis found that ACS patients had significantly higher rates of myocardial infarction (MI) or target-vessel revascularisation (TVR) than those with stable ischaemic heart disease for all FFR categories. Annualised rates over 3.4 years of follow-up were 12.8% versus 5.3% among patients with an FFR of 0.75–0.80, falling to 6.2% versus 2.6% at an FFR greater than 0.90.
As Abdul Hakeem (Central Arkansas for Veterans Healthcare System, Little Rock, USA) and co-researchers expected, the 206 ACS patients had more atherosclerosis risk factors than the 370 with stable disease.
However, the increased risk of MI/TVR persisted among 200 ACS patients who were matched to 200 stable disease patients on these risk factors, they report in the Journal of the American College of Cardiology.
And in the propensity-matched cohort, stable disease patients had similar MI/TVR rates at all FFR values, whereas ACS patients had markedly higher rates in the FFR “grey zone” (0.75–0.80) and “borderline zone” (0.81–0.85) than at higher values.
The team found an FFR of 0.81 – close to the standard cutoff of 0.80 – to be optimal for distinguishing between stable disease patients who did and did not have MI/TVR. However, for NSTE-ACS patients, the best cutoff was 0.84, with patients falling below this threshold having a 2.62-fold higher risk than those with higher values.
This higher cutoff suggests “that transient microvascular dysfunction might be falsely elevating FFR in a portion of NSTE-ACS patients”, say William Fearon (Stanford University, California, USA) and co-authors of an accompanying editorial.
However, they highlight several issues, including technical factors and study population characteristics, as well as the fact that mortality was not included as an endpoint, which lead them to the conclusion that a higher cutoff should not currently be advocated.
The editorialists say that the potential for an increased event rate after deferring PCI based on FFR in NSTE-ACS patients should be acknowledged. But they stress: “Until we have more data, FFR-based decision making concerning revascularization of clear culprit stenoses of STEMI and NSTE-ACS should be discouraged.”
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