Cut-off Values of Lesion and Vessel Quantitative Flow Ratio in De Novo Coronary Lesion Post-Drug-Coated Balloon Therapy Predicting Vessel Restenosis at Mid-Term Follow-Up
Drug-coated balloons (DCBs) have emerged as a promising alternative to drug-eluting stents for the treatment of specific subsets of de novo coronary lesions. DCBs are coated with paclitaxel, which inhibits arterial smooth muscle cell proliferation, thereby preventing restenosis. Unlike stents, DCBs do not leave a permanent implant in the vessel, which can reduce the duration of dual antiplatelet therapy and avoid chronic inflammation. This makes DCBs particularly suitable for complex lesions and small vessels. However, the success of DCB therapy depends on optimal lesion preparation and reliable predictors of outcomes immediately post-treatment. One such predictor is the quantitative flow ratio (QFR), a non-invasive method based on three-dimensional quantitative coronary angiography (3D-QCA) and contrast flow velocity during coronary angiography (CAG). QFR eliminates the need for invasive fractional flow reserve (FFR) procedures, which are costly and require hyperemia induction.
This study aimed to assess the serial angiographic changes in de novo coronary lesions following DCB therapy and to determine the cut-off values of lesion and vessel QFR that predict vessel restenosis (defined as diameter stenosis [DS] ≥50%) at mid-term follow-up. The study retrospectively analyzed data from patients who underwent DCB therapy between January 2014 and December 2019 across multiple centers. The patients were divided into two groups based on their QFR performances at follow-up: Group A, with target vessel DS ≥50%, and Group B, with target vessel DS <50%. The median follow-up time was 287 days for Group A and 227 days for Group B.
The study enrolled 112 patients with 112 target vessels, of which 41 were in Group A and 71 in Group B. The prevalence of vessel restenosis post-DCB therapy at mid-term follow-up was 36.61%. The baseline clinical characteristics, including age, sex, hypertension, diabetes, smoking status, and history of PCI, coronary artery bypass graft, or myocardial infarction, were similar between the two groups. Similarly, parameters during DCB therapy, such as target vessel, lesion length, maximal diameter of the pre-dilation balloon, and maximal inflation pressure with DCB, showed no significant differences between the groups.
Post-DCB therapy, QFR performances were analyzed based on CAG images. The results showed that the diameter stenosis (DS%) and area stenosis (AS%) were more severe in Group A than in Group B. Specifically, the median DS% was 46.9 in Group A compared to 35.90 in Group B, and the median AS% was 51.60 in Group A compared to 40.30 in Group B. Additionally, both vessel QFR and lesion QFR were significantly lower in Group A than in Group B. The median vessel QFR was 0.81 in Group A versus 0.94 in Group B, and the median lesion QFR was 0.89 in Group A versus 0.96 in Group B.
At follow-up, the QFR performances continued to show significant differences between the two groups. The minimal luminal diameter and area were smaller in Group A than in Group B, with median values of 1.20 mm and 1.90 mm² in Group A compared to 1.70 mm and 3.00 mm² in Group B, respectively. The DS% and AS% were also more severe in Group A, with median values of 53.00% and 58.40%, respectively, compared to 33.00% and 33.10% in Group B. The vessel QFR and lesion QFR remained lower in Group A, with median values of 0.78 and 0.88, respectively, compared to 0.96 and 0.98 in Group B.
To explore the association between vessel restenosis and risk factors, univariate and multivariate linear regression analyses were performed. Univariate analysis identified maximal pre-dilatation pressure, maximal inflation pressure with DCB, DS% post-DCB dilatation, vessel QFR post-DCB dilatation, and lesion QFR post-DCB dilatation as significant factors associated with DS%. However, in multivariate analysis, only vessel QFR was independently associated with DS%, with a coefficient of -0.233.
The study also determined the cut-off values of lesion and vessel QFR that predict target vessel restenosis at follow-up. The cut-off value for lesion QFR was 0.905, with an area under the curve (AUC) of 0.741, sensitivity of 0.817, and specificity of 0.561. The cut-off value for vessel QFR was 0.890, with an AUC of 0.796, sensitivity of 0.746, and specificity of 0.780. These results indicate that when the lesion QFR is less than 0.905 or the vessel QFR is less than 0.890 post-DCB therapy, there is a higher risk of vessel restenosis at follow-up.
The findings of this study highlight the importance of QFR as a non-invasive tool for predicting angiographic outcomes following DCB therapy. Lower QFR values post-DCB therapy are associated with a higher risk of vessel restenosis at mid-term follow-up. The cut-off values of lesion QFR (0.905) and vessel QFR (0.890) provide valuable thresholds for clinicians to assess the risk of restenosis and make informed decisions regarding further interventions.
The study has several limitations. First, it is retrospective in design, which introduces potential selection bias and limits the availability of some patient parameters. Second, the small sample size prevented the division of patients into subgroups, limiting the generalizability of the results. Third, the study did not assess clinical outcomes, emphasizing the need for larger, randomized registry studies to validate the clinical implications of QFR values.
In conclusion, QFR is a valuable tool for predicting vessel restenosis following DCB therapy in de novo coronary lesions. The cut-off values of lesion QFR and vessel QFR provide clinicians with reliable thresholds to assess the risk of restenosis and guide treatment decisions. Further research is needed to validate these findings and explore their clinical applications in larger, diverse patient populations.
doi.org/10.1097/CM9.0000000000001577
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