TARGET FFR: A randomized trial of physiology-guided PCI optimization
Reported from the TCT Congress 2020
At TCT Connect 2020, Damien Collison presented the results of the TARGET FFR trial. Carlos Collet provides a summary of the key messages.
Post-PCI fractional flow reserve (FFR) has been identified as a predictor of adverse clinical events after PCI. Therefore, strategies that aim at increasing the degree of functional revascularization may lead to superior clinical outcomes. TARGET-FFR is a single-centre, randomized clinical trial of patients with chronic coronary syndromes and hemodynamically significant lesions undergoing angiography-guided PCI.
Patients were randomized in two groups after the operator declared the PCI to be successful. In the control group, coronary physiology assessment post-PCI was performed in a blinded fashion. In the experimental arm if the post-PCI FFR was <0.90 the so-called physiology-guided incremental optimization strategy (PIOS) was applied. PIOS entailed on the evaluation of the post-PCI FFR pullback curve to ascertain whether further optimization was feasible. Optimization targeted the presence of residual FFR curve step-ups defined as focal pressure drops ≥0.05 FFR units. The primary end-point was the proportion of patients achieving final post-PCI FFR ≥0.90.
Secondary end-point of patients with final FFR ≤0.80 significantly lower in the PIOS group
A total of 260 patients were randomized to PIOS or control. Rates of post-dilatation were very high in both groups (99% and 97%, respectively). There were no significant differences in procedural characteristics, number of stents or stent length between arms. Notably, before randomization 29% of the cases had a post PCI FFR ≤0.80 whereas only 32% had functional satisfactory results (post-PCI FFR ≥0.90). Moreover, the predominant pathophysiological feature leading to suboptimal functional results was the presence of diffuse disease. In the 131 patients randomized to PIOS, substrate for further optimization was observed in 46% (60/131) of the cases and PIOS was applied in 31% (40/131) of these cases. The application of PIOS resulted in a significant increase in post-PCI FFR from 0.76±0.08 to 0.82±0.06, p<0.001. PIOS was performed mainly by means of further post-dilation (57.5%) and additional stent implantation (30%). Despite higher post-PCI FFR in the PIOS arm, the primary end-point was not met due to a non-significant difference in the proportion of patients with post-PCI FFR ≥0.90 (38.1% PIOS vs. 28.1% controls, p=0.099). However, the secondary end-point of patients with final FFR ≤0.80 was significantly lower in the PIOS group (18.6% vs. 29.8%, p= 0.045).
Main findings
TARGET FFR is one of the first trials proposing an FFR guided optimization strategy based on FFR pullbacks. The main findings show that:
- sub-optimal physiologic results after angiography-guided PCI are common,
- functional substrate for PCI optimization (i.e. residual focal FFR drops) was observed in almost half of the cases,
- the PIOS approach showed to increase post-PCI FFR but failed to significantly increase the proportion of patients with acceptable (FFR ≥0.90) post-PCI,
- the application of PIOS succeeded in decreasing the number of patients with an FFR <0.80 post PCI.
The investigators should be commended for this meticulously executed study. The results of this apparent negative RCT expand the concept of invasive coronary physiology from a diagnostic tool to ascertain lesion significance to a tool for helping planning and guiding PCI. The physiology-based optimization strategy showed to improve FFR post-PCI; however, the conversion of this additional functional gain to clinical benefit remains to be established. A clinical trial addressing the impact of an FFR pullback guided-PCI with post-PCI pullback-based optimization strategy on clinical outcomes is still warranted.
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