Angiographic completeness of revascularization was no predictor of clinical events when stenting is guided by fractional flow reserve (FFR), researchers confirmed for acute coronary syndrome (ACS) patients.
Residual SYNTAX scores were no different between patients who did and did not experience major adverse cardiovascular events in the 2 years after achieving functionally-complete revascularization with percutaneous coronary intervention (PCI; 7.2 versus 6.6, P=0.23).
This was corroborated by a Kaplan-Meier curve analysis showing no difference in event rates by SYNTAX score, according to William Fearon, MD, of Stanford University Medical Center in Stanford, California, and colleagues reporting in the Sept. 18 issue of the Journal of the American College of Cardiology.
Multivariable adjustment confirmed that the residual SYNTAX score was no predictor of the primary endpoint -- all-cause death, nonfatal MI, and any repeat revascularization -- or any component of it. Overall, 12.6% of ACS patients suffered these events.
"After complete revascularization of functionally significant stenosis by FFR, the extent of residual angiographic disease is not associated with subsequent ischemic events in patients presenting with ACS," the authors concluded. "These results suggest that functionally complete revascularization is applicable even in ACS patients with potentially vulnerable nonculprit stenoses."
A similar finding had previously been shown by this group for stable patients getting FFR-guided PCI.
Fearon's group performed a post hoc study of the the DANAMI-3-PRIMULTI, FAME, and FAMOUS-NSTEMI studies, pooling the 547 patients who presented with ACS and got functionally complete revascularization (intervention in infarct- and non-infarct-related arteries with FFR 0.80 or below).
There were notable differences in trial design among the three studies, according to Fearon and colleagues, who said their findings were hypothesis-generating and had potentially inadequate statistical backup.
"There has been concern regarding the safety and accuracy of FFR measurements in the ACS setting," the authors noted, in part due to the potential for transient coronary microvascular dysfunction in the culprit vessel, and the possibility that nonculprit disease (which is not hemodynamically significant based on FFR) might cause events after PCI for ACS.
These concerns were not supported by the current study -- at least not in patients treated with dual antiplatelet therapy for 1 year, the investigators said.
What Fearon's group has shown "may help tip the balance in favor of systematic FFR-guided complete functional revascularization as the most appropriate strategy for predicting optimal outcomes despite the presence of potentially 'active' residual lesions, even in patients with unstable coronary disease," commented Marie-Claude Morice, MD, of the Institut Cardiovasculaire Paris Sud.
In an accompanying editorial, Morice discussed the weaknesses of the SYNTAX score, such as its low intraobserver and interobserver reproducibility and the way it takes into account the presence of lesions in very small, probably functionally insignificant vessels.
"Before driving the final nail in the coffin of the SYNTAX score, we may want to consider that this stratification tool was originally designed to predict the outcome of patients with complex multivessel and left main disease and high scores of lesion severity, and not for the purpose of determining the prognosis of those with low scores," she nonetheless wrote.
Fearon has received institutional research support from Abbott, Medtronic, and CathWorks; has a consulting relationship with Boston Scientific; and has minor stock options with HeartFlow.
Morice disclosed no relevant conflicts of interest.