Results
Baseline Characteristics and Procedural Data
Sixty-six patients (mean age, 68.97 ± 9.67 years) with a coronary lesion of at least intermediate degree (≥40% by QCA) were enrolled in the analysis. Clinical baseline characteristics are outlined in Table 1. Single-vessel disease was present in 20 patients (30.3%) and multivessel disease was present in the remaining 46 patients (69.7%). The average QCA values were 64.96 ± 15.93% for percent diameter stenosis, 9.30 ± 4.76 mm for lesion length, 0.90 ± 0.41 mm for MLD, and 2.55 ± 0.63 mm for reference diameter.
There were no periprocedural or postprocedural complications associated with the intracoronary use of FFR and OCT. Predilatation was performed in 32 lesions (48.5%) and postdilatation was performed in 27 lesions (40.9%). The overall procedural-related data are provided in Table 2. In 2 cases, there were persistent hyperemic postinterventional trans-stent pressure gradients of 0.65 and 0.77 (both 0.50 before PCI), even after additional non-compliant balloon inflation at burst pressure and exclusion of stent malapposition.
Clinical Outcome
As presented in Table 1, complete follow-up was available in all 66 patients during a mean period of 15.11 months (range, 6–28 months). No patient developed acute or subacute stent thrombosis or required revascularization by coronary artery bypass graft surgery. Two patients with NSTEMI concurrently required TLR, whereas 1 TLR and 1 NSTEMI occurred independently. There were 3 reported deaths of any cause within the study cohort; 1 patient with a final FFR of 0.93 died 15 months after the procedure due to a sudden cardiac death, 1 patient with reduced LVEF of 37% died of decompensated heart failure (final FFR, 0.90), and another patient with a final FFR of 0.86 died due to a traumatic intracerebral hemorrhage.
OCT-derived Intrastent Percent Area Stenosis and Fractional Flow Reserve Predict Clinical Outcome
In linear regression analysis, OCT-derived intrastent %AS was significantly related to post stent FFR (r = 0.491; P<.001)(Figure 2), whereas no significant correlation was found between FFR and MSA or between FFR and intrastent MLD (both P>.05).
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Figure 2.
Linear regression analysis displays the association between intrastent percent area stenosis (%AS) and fractional flow reserve (FFR) measurements after percutaneous coronary intervention (PCI).
We then determined the diagnostic efficiency of both post stent FFR and intrastent %AS to predict clinical events. ROC analysis demonstrated a moderate diagnostic efficiency (AUC = 0.768; 95% CI, 0.562–0.973) for final FFR to predict MACE at 20 months at a best cut-off value of 0.905 (sensitivity, 71.4%; specificity, 85.0%; PPV, 62.5%; NPV, 89.5%) (Figure 3). According to this optimal cut-off value, patients were categorized into a group with an FFR ≤0.905 (n = 26; 39.4%) and a group with an FFR >0.905 (n = 40; 60.6%).
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Figure 3.
Receiver-operating characteristic curve for postinterventional fractional flow reserve (FFR)-derived and optical coherence tomography (OCT)-derived intrastent percent area stenosis (%AS) to predict major adverse cardiac event (MACE) after 20 months.
The differences in clinical baseline and follow-up characteristics between the two groups are displayed in Table 1, exhibiting a significantly higher clinical event rate in patients with an FFR ≤0.905 compared to those with an FFR >0.905.
OCT-derived intraluminal stent dimensions in lesions with an FFR ≤0.905 had a higher degree of intrastent %AS (16.60 ± 4.75% vs 7.01 ± 3.49%, respectively; P<.001). Baseline FFR (0.661 ± 0.122 vs 0.739 ± 0.094, respectively; P<.01) as well as postinterventional FFR values (0.862 ± 0.053 vs 0.947 ± 0.027, respectively; P<.001) were significantly lower in lesions with a final FFR ≤0.905 compared to those with an FFR >0.905. There was a weak correlation between these pre- and postinterventional FFR values (r = 0.186; P<.001), whereas no association could be demonstrated between patients with and without stent edge dissections regarding the incidence of MACE (P>.05; data not shown). Further differences of procedural and OCT data between the groups are displayed in Table 2.
Moreover, ROC analysis for intrastent %AS to predict clinical events was analyzed and also demonstrated a moderate diagnostic efficiency (AUC = 0.807; 95% CI, 0.613–1.000) at an optimal cut-off value of 16.85% (sensitivity, 85.7%; specificity, 65.0%; PPV, 46.2%; NPV, 92.9%) (Figure 3).
According to the Kaplan-Meier method, the 20-month cumulative incidence of MACE was significantly greater in patients with an FFR ≤0.905 compared with patients who had an FFR >0.905 (35.9% vs 5.3%, respectively; P=.01) (Figure 4A). Furthermore, patients with an intrastent %AS >16.85% had a significantly higher 20-month cumulative incidence of MACE (51.3%) compared to individuals with an intrastent %AS ≤16.85% (8.0%; P<.001) (Figure 4B).
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Figure 4.
The freedom from major adverse cardiac event (MACE) rate is depicted using Kaplan-Meier estimates for patients with stented lesions characterized by (A) fractional flow reserve (FFR) >0.905 and FFR ≤0.905 after percutaneous coronary intervention (PCI); and (B) an intrastent percent area stenosis (%AS) ≤16.85% and %AS >16.85%.