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The coronary bifurcation stenting studies did not demonstrated advantage of any two-stent technique over provisional T-stenting technique. One possible explanation is that some of bifurcation lesions treated were not functionally significant and as such treated or not will not influence clinical outcome. FFR guided PCI has shown to reduce MACE compared to angiography guided PCI. However, FFR remains underutilized and most decision are still based on angiographic %DS. In bifurcation lesions, the assessment of the severity of the stenosis is more challenging due to the step down phenomenon.
Patients with stable and unstable angina (with normal baseline troponin values) were included. A fractional flow reserve measurement was systematically performed in patients with coronary bifurcation lesions having by visual diameter stenosis >50% in main vessel and side branche. All main and side branches were interrogated with intracoronary pressure recording Prime Wire (Volcano, USA) at baseline and after giving 100-200 mcg adenosine and then in stepwise fashion 60mcg, 120mcg, 180 mcg, 240 mcg. If patients developed AV-block, the previous dose was repeated for recording. Patients with significant FFR in main vessel (<0.80) were treated with provisional stent strategy.
Overall, 77 patients with visual angiographically significant coronary bifurcation lesions were included in the study. Of which, 39 patients were treated with DES, because of significant FFR results whereas 37 patients (48%) had deferred intervention. 62% were males, with mean age 67±10 years. The mean FFR in MV in treated vs. deferred group was 0.70±0.07 vs 0.85±0.03, p<0.001 and in SB 0.79±.11 vs. 0.88±.04, p<0.001. There was significant difference in percentage diameter stenosis in proximal main vessel in treated vs. deferred groups (59±18% vs 40±20%, p<.001), in distal main vessel (70±11 vs 51±20, p<.001), but not in side branches (55±22 vs 49±24, p=.248). Based on ROC analysis we defined main vessel score (MVS) – a sum of MVprox percentage DS >55% and MVdist percentage DS>70% as cut-off values (AUC=0.828, p<.001) for predicting significant FFR in main vessel (MVS=0, 4/24, 17% significant FFR; =1, 14/31, 45% significant FFR, =2, 21/22, 96% significant FFR). On logistic regression analysis the MVS was one of the independent predictors of significant FFR in the main vessel (OR=16.382, CI 1.732-54.963, p=.033.
Almost half of the patients with MV prox %DS >55% or MV dist %DS>70% do not have functional significant stenosis. Our ROC analysis have defined that if the both are met there is 96% chance for the vessel stenosis to be functional significant. Our data require further validation for patients included in bifurcation stenting studies in future.
IMAGING: FFR and Physiologic Lesion Assessment