Coronary hemodynamics of stent implantation after suboptimal and optimal balloon angioplasty

OBJECTIVES: This study was performed to evaluate hemodynamic alterations of stent implantation after Doppler flow-guided balloon angioplasty (BA). BACKGROUND: There is controversy regarding the effect of stent implantation on coronary hemodynamics after suboptimal and optimal BA. METHODS: A total of 523 of 620 patients underwent Doppler-guided BA in the setting of a multicenter study and were analyzed before and after additional stent implantation. Balloon angioplasty was considered optimal when the diameter stenosis (DS) was ≤ 35% and coronary flow reserve (CFR) was >2.5 and suboptimal if these two criteria were not met. Coronary flow reserve was also measured in an angiographically normal artery to determine relative CFR. Patients were followed for 12 months to document major adverse cardiac events (MACE). RESULTS: The main difference between patients with suboptimal BA (n = 195 [51%]) and optimal BA (n = 184 [49%]) was a more pronounced increase in baseline blood flow velocity (15 ± 8 to 22 ± 11 vs. 14 ± 8 to 16 ± 10 cm/s, p < 0.01). Coronary flow reserve improved after stent implantation in both patient groups, owing to a reduction in residual lumen obstruction, as determined by angiographic (%DS) and Doppler flow criteria (hyperemic blood flow velocity, relative CFR), and was associated with a decrease in MACE (16% vs. 7% in optimal BA group, p = 0.05; and 27% vs. 11% in suboptimal BA group, p = 0.007). CONCLUSIONS: Stent implantation enhances CFR after suboptimal and optimal Doppler-guided BA, owing to a reduction in residual lumen obstruction - determined by angiographical and Doppler flow criteria - as the underlying mechanism for an improved clinical outcome.