Background: Many studies have indicated that a small lumen size is one of the most important predictors of acute events and of late restenosis after balloon angioplasty or stent implantation. In the last few years many studies have shown that intravascular ultrasound (IVUS) guidance makes it possible to optimize stent implantation. The aim of this pilot study was to evaluate the feasibility and safety of IVUS imaging of small vessels. Secondary endpoints were the immediate and long-term results of IVUS-guided elective BeStent implantation in small vessels.
Methods: Fourteen symptomatic patients with small coronary vessel (mean angiographic reference diameter 2.3 +/- 0.2 mm) disease underwent IVUS-guided BeStent implantation. IVUS success was defined as the achievement of a final minimal intrastent cross-sectional area (CSA) > 90% of the smaller reference lumen CSA.
Results: IVUS evaluation was feasible in all patients without any clinical or angiographic adverse events. Procedural success was achieved in all patients with implantation of a BeStent 15 mm. No major complication (death, myocardial infarction, stent acute or subacute thrombosis, coronary artery bypass, re-coronary angioplasty) occurred during the in-hospital phase. Two non-flow-limiting, asymptomatic coronary dissections were detected after stent expansion. The post-stenting lesion stenosis rate decreased from 72.9 +/- 12.9% to 0.75 +/- 11.7% with an acute gain of 1.8 +/- 0.4 mm. The final IVUS minimal stent CSA was 5.6 +/- 1.1 mm2. The IVUS criteria of adequate stent expansion were reached in 11 (78.6%) patients. At 6 months of follow-up, the rate of angiographically diagnosed in-stent restenosis was 30.7%; the 6-month late loss in stent diameter was 1.1 +/- 0.6 mm. No patient died or presented with a myocardial infarction. The target lesion revascularization rate was 30.7%.
Conclusions: Coronary IVUS-guided stenting can be performed in small vessels with a high success rate and low incidence of in-hospital complications. However, despite these encouraging short-term results, the long-term clinical and angiographic outcome is less favorable. Further larger and randomized IVUS studies, probably employing more aggressive IVUS criteria, are needed to clarify the true role of IVUS guidance in this particular field.