Objectives: This study evaluated the acute physiological gain of adjunctive intravascular ultrasound (IVUS) guided balloon angioplasty and stent implantation.
Background: Recent studies indicate safe coronary luminal enlargement and "stent-like" long-term outcomes using upsized balloons guided by IVUS.
Methods: After angiographically guided balloon angioplasty in 20 patients with 1-vessel disease and normal left ventricular function, IVUS was performed to determine the size of the adjunctive balloon using the mean of the maximal luminal diameter and the maximal diameter of the external elastic membrane measured in the adjacent proximal and distal reference segments. Serial adenosine-induced hyperemic blood flow velocity measurements were performed using a 0.014" Doppler guide wire to determine the physiological lumen obstruction after standard balloon angioplasty, followed by IVUS-guided balloon angioplasty and stent implantation.
Results: Upsized balloon angioplasty (increase balloon size: 0.98 +/- 0.26 mm; balloon:artery ratio 1.35 +/- 0.21) resulted in an additional increase of arterial dimensions: minimal lumen diameter (MLD) 2.18 +/- 0.38 mm to 2.73 +/- 0.51 mm; percent diameter stenosis (%DS) 34 +/- 13% to 19 +/- 22%; IVUS assessed minimal lumen area (MLA) 7.53 +/- 1.55 mm2 to 10.24 +/- 2.22 mm2 (all p < 0.0001). Major dissections (> or = type C) did not occur. Hyperemic blood flow velocity increased from 49.8 +/- 20.1 cm/s to 59.1 +/- 22.9 cm/s (p < 0.05) after IVUS-guided balloon angioplasty. Adjunctive stent implantation resulted in a further increase of MLD to 3.84 +/- 0.51 mm, %DS to -9 +/- 21% and MLA to 13.39 +/- 1.80 mm2 (all p < 0.0001), while hyperemic blood flow velocity remained unchanged (61.2 +/- 24.7 cm/s, p = 0.7).
Conclusions: Upsized IVUS-guided balloon angioplasty increases arterial coronary dimensions and the distal hyperemic blood flow velocity. Adjunctive stent implantation does not yield a further gain in the hyperemic blood flow velocity, indicating the absence of a functional residual lumen obstruction after IVUS-guided balloon angioplasty. This may explain a similar clinical outcome reported after those coronary interventions.