Objective analysis of residual fractional flow reserve (FFR) pullback tracings after successful percutaneous coronary intervention (PCI) could be a practical tool to detect the major residual FFR gradient, which may indicate a need for further adjunctive intervention, say researchers.
Published online Monday and in the Sept. 13 issue of JACC: Cardiovascular Interventions, the study noted that while recent research has shown that post-PCI FFR is associated with clinical outcomes, and post-PCI FFR pullback tracings provide clinically relevant information on the residual FFR gradient, there are currently no objective criteria for assessing post-PCI FFR pull back tracings.
Led by Seung Hun Lee, MD, PhD, from the Sungkyunkwan University School of Medicine, Seoul, South Korea, the team analyzed the clinical implications of the residual FFR gradient, and use of the dFFR(t)/dt algorithm, after angiographically successful PCI – finding that the dFFR(t)/dt algorithm can detect the presence of the major residual FFR gradient from post-PCI FFR pullback tracings more objectively than conventional visual assessment.
“Objective analysis of post-PCI FFR pull back tracings using dFFR(t)/dt improved classification agreement on the presence of the major residual FFR gradient among operators,” said Lee and colleagues, adding that the presence of the major residual FFR gradient – defined by dFFR(t)/dt after angiographically successful PCI – was independently associated with an increased risk of target vessel failure (TVF) at 2 years.
Lee and colleagues analyzed data from a total of 492 patients who underwent angiographically successful PCI and post-PCI FFR measurement with pullback tracings.
The presence of the major residual FFR gradient after PCI was assessed by both conventional visual interpretation of the pullback tracings and objective analysis using the instantaneous FFR gradient per unit time (dFFR(t)/dt) with a cutoff value of ≥0.035.
Analysis revealed that 33.9% of the study population had the major residual FFR gradient defined by dFFR(t)/dt.
A classification agreement between two independent operators for the presence of the major residual FFR gradient was compared before and after providing dFFR(t)/dt results. Analysis showed that classification agreement between operators’ assessments increased with dFFR(t)/dt results compared with conventional visual assessment (Cohen’s kappa = 0.633 to 0.819; P < 0.001; intraclass correlation coefficient: 0.776 to 0.901; P < 0.001).
Furthermore, TVF, a composite of cardiac death, target vessel myocardial infarction or clinically driven target vessel revascularization at 2 years, was compared according to the presence of the major residual FFR gradient – finding that patients with major residual FFR gradient were associated with a higher risk of TVF at 2 years than those without major residual FFR gradient (9.0% vs 2.2%; P < 0.001).
“Even after angiographically successful PCI, the presence of the major residual FFR gradient determined by dFFR(t)/dt is significantly associated with an increased risk of TVR at 2 years, regardless of post-PCI FFR or %FFR increase,” said Lee and colleagues.
“Conversely, there was no prognostic impact of a visually defined major residual FFR gradient.”
The authors said that further research is now needed to assess the clinical impact and possible procedural optimizations that come from using dFFR(t)/dt.
Risk marker or risk maker?
Writing in an accompanying editorial, Nils P. Johnson, MD, MS, from the McGovern Medical School at UTHealth and Memorial Hermann Hospital, Houston, and Carlos Collet, MD, PhD, from the Cardiovascular Center Aalst at OLV Clinic, Aalst, Belgium, noted that a large body of research has shown an association between FFR immediately after PCI and subsequent events.
“What remains unclear is whether post-PCI FFR represents just a marker of disease extent (statistically associated with outcomes but not in causal fashion) or a risk factor (ie, a causal mediator of outcomes) modifiable through further PCI,” they said.
The editorialists added that although the new data expand insights by linking subsequent clinical events with residual FFR pullback gradients – and not just a single, distal measurement – three of its findings suggest that post-PCI FFR is a “bystander” rather than a target for treatment.
“In our opinion, we must remain focused on the clinical issue: reducing TVF after stenting, generally driven by symptom-related TVR but occasionally by spontaneous TVMI,” they said. “Worrying about FFR after PCI is probably too late.”
“Unless post-PCI physiology can lead to reduced TVF beyond what can be achieved by intracoronary imaging, then it represents only a risk marker, not a therapeutic target,” the commentators said, adding that as such it would carry limited clinical value, as measuring unmodifiable risk “remains largely the domain of the armchair actuary, not the interventional cardiologist.”
Lee SH, Kim J, Lefieux A, et al. Clinical and Prognostic Impact From Objective Analysis of Post-Angioplasty Fractional Flow Reserve Pullback. JACC Cardiovasc Interv 2021;14:1888-1900.
Johnson NP, Collet C. Can FFR After Stenting Help Reduce Target Vessel Failure? JACC Cardiovasc Interv 2021;14:1901-1903.
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