What are the causes of a suboptimal FFR after coronary stent deployment? Insights from a consecutive series using OCT imaging

Abstract

Aims: Fractional flow reserve (FFR) can be used to detect a suboptimal result after percutaneous coronary intervention (PCI). A lower post-procedure FFR (<0.90) has been shown to be associated with adverse clinical outcomes at follow-up. This pilot study aimed to understand the mechanisms resulting in a suboptimal FFR and whether optical coherence tomography (OCT)-guided optimisation could improve final FFR.Methods and results: Thirty-five patients undergoing complex PCI were prospectively enrolled. After stenting and post-dilatation, OCT and pressure wire were performed. An FFR threshold <0.90 after PCI was defined as suboptimal and mandated further PCI optimisation. A satisfactory post-PCI FFR (predefined as ≥0.90) was achieved immediately after conventional PCI in 14 patients (40%) and in this group no further treatment was performed. Minor abnormalities (stent malapposition of 200-500 µm) were observed with OCT in three of these patients. Suboptimal functional results after conventional stenting (predefined as an FFR <0.90) were found in 21 patients (60%). In thirteen out of these 21 patients (61.9%), OCT demonstrated a suboptimal stent result. Subsequent OCT-guided optimisation was performed resulting in a higher final FFR (increase from 0.80±0.02 to 0.88±0.01; p=0.008).Conclusions: Despite a satisfactory angiographic result, a suboptimal functional result is evident in a substantial proportion of patients undergoing complex PCI. Implementation of an OCT-guided PCI optimisation protocol may reveal potentially treatable causes, allowing optimisation of the post-PCI functional result.

A randomized controlled trial of a physiology‐guided percutaneous coronary intervention optimization strategy: Rationale and design of the TARGET FFR study

“…In a cohort of 13 patients who fulfilled both functional and OCT‐defined criteria for suboptimal stent results, Wolfrum et al increased the mean post‐PCI FFR in this group from 0.80 ± 0.02 to 0.88 ± 0.01 through a combination of additional stent postdilation (46%), additional stenting (39%) or a combination of both strategies (15%). Larger increases in FFR value were observed in the seven patients who received additional stents …”

Fractional Flow Reserve following Percutaneous Coronary Intervention

“…Underdeployed stents are therefore known to be associated with an increased risk of major adverse cardiac events (MACEs) and target vessel failure (TVF) [4]. Lower post-PCI FFR measurements are correlated with suboptimal PCI results and predictive of future clinical outcomes [12,14].…”

“…In a cohort of patients with post-PCI FFR values ≤ 0.85, IVUS analysis revealed stent under-expansion in up to 74% of treated vessels [17]. Incomplete lesion coverage is the other main finding associated with a persistent pressure gradient after PCI [14]. Hence, post-PCI FFR is a surrogate for an optimal PCI result especially stent expansion.…”

“…In the presence of a significant transstent gradient, further postdilation is advisable [10]. If there are still concerns regarding stent deployment or the exact mechanism remains unconfirmed, imaging through IVUS or OCT can be utilized to provide detailed visualization and precise quantification of expansion and plaque shift/protrusion [14,17,27].…”

“…However, diffuse disease throughout the vessel is typically not amenable to further intervention, as there is no discrete lesion amenable to stenting [32]. Wolfrum et al used OCT guidance to optimize the final FFR result and found 23% of stented segments were not amenable to PCI optimization and the FFR remained suboptimal regardless, usually secondary to diffuse distal disease [14].…”