The validation of fractional flow reserve in patients with coronary multivessel disease: a comparison with SPECT and contrast-enhanced dobutamine stress echocardiography.

UNLABELLED: Fractional flow reserve (FFR) is a new but well established parameter for the hemodynamic evaluation of coronary stenoses. A FFR below 0.75 was validated as functionally significant in coronary one or two vessel disease. This study was designed to prospectively define the best FFR cut off value (BCV) in patients with multivessel disease using two noninvasive tests, myocardial perfusion scintigraphy (SPECT) and contrast-enhanced dobutamine stress echocardiography (DSE) as reference methods. METHODS: 47 symptomatic patients (29 male, mean age 64+/-10 yrs) with angiographically intermediate coronary lesions (50-75% diameter stenosis) entered the study. DSE (5-40 microg/min/kg dobutamine) was performed after intravenous injection of a second generation transpulmonary contrast agent. SPECT (Tc-99m-MIBI) was done at peak stress. All tests (DSE, SPECT and FFR) were performed within 4 weeks. RESULTS: SPECT yielded positive results in 15 and DSE in 16 patients, respectively. Mean FFR measured in the target lesion (RCA n=10; LAD n=22, RCX n=15) was 0.80+/-0.13. FFR was <0.75 in 15 patients. By performing a ROC analysis the BCV (highest sum of sensitivity and specificity) was found at 0.75. At this cut off value using both non-invasive tests as reference method, sensitivity and specificity were 83 and 77%. CONCLUSION: In patients with multivessel disease, a FFR <0.75 identifies a hemodynamically relevant lesion as compared to DSE and SPECT. This study underlines that FFR criteria are also applicable in patients with complex coronary artery disease.

Early time course of neointima formation and vascular remodelling following percutaneous coronary intervention and vascular brachytherapy of in-stent restenotic lesions as assessed by intravascular ultrasound analysis.

In-stent restenosis (ISR) represents the major limitation of stent implantation. Treatment, although of relative technical ease, is unsatisfactory due to a high incidence of recurrent restenosis. Vascular brachytherapy (VBT) has emerged as a powerful adjunct therapeutic modality to treat ISR. Inhibition of neointima formation has been regarded as the relevant mechanism of action. Yet, positive remodelling has been suspected as another contributing factor. Since only very few precise analyses of the extent, distribution and time course of the respective mechanims exist, the goal of the present study was to describe the changes of the vessel geometry at the target lesion and at the reference site following angioplasty and VBT of ISR in 42 patients by means of quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS) before and after the index procedure and at the 3 and 6 month follow-up. By QCA the acute lumen gain measured 2.2+/-0.8 mm, the late lumen loss at 3 months was 0.1+/-0.5 mm and at 6 months 0.4+/-0.7 mm. By IVUS luminal cross-sectional area increased from 1.5+/-1.2 mm(2) to 7.9+/-1.9 mm(2) (p<0.001). The intima hyperplasia cross-sectional area at 3 months was only 0.2+/-1.0 mm(2) (p=0.191), but increased to 0.7+/-0.6 mm(2) (p<0.001) at 6 months resulting in a lumen cross-sectional area of 7.1+/-1.7 mm(2). Stent dimensions did not show any significant changes over time. The external elastic membrane cross-sectional area at 3 months increased by 1.3+/-1.9 mm(2) (p<0.001), and showed a further increase by 0.7+/-2.9 mm(2) at 6 months. Positive remodelling could be demonstrated also at the reference segment. In conclusion the absolute amount of intima hyperplasia during a 6-month follow-up period after VBT of ISR is low and most pronounced between the third and sixth month. Besides this, predominantly within the first 3 months of follow-up, significant positive remodelling could be demonstrated at the target lesion and at the reference site. Both observed effects may contribute to the preservation of the vessel lumen.