Background: AVID (Angiography Versus Intravascular ultrasound-Directed stent placement) is a multicenter, randomized controlled trial designed to assess the effect of intravascular ultrasound (IVUS)-directed stent placement on the 12-month rate of target lesion revascularization (TLR).
Methods and results: After elective coronary stent placement and an optimal angiographic result (<10% stenosis), 800 patients were randomized to Angiography- or IVUS-directed therapy. Blinded IVUS was performed in the Angiography group without further therapy. In the IVUS group, IVUS criteria for optimal stent placement (<10% area stenosis, apposition, and absence of dissection) were applied. Final minimum stent area was 6.90+/-2.43 mm(2) in the Angiography group and 7.55+/-2.82 mm(2) in the IVUS group (P=0.001). In the IVUS group, only 37% with inadequate expansion (<90%) received further therapy. The 12-month TLR rate was 12.0% in the Angiography group and 8.1% in the IVUS group (P=0.08, 95% confidence level [CI], [-8.3% to 0.5%]). When vessels with a distal reference diameter <2.5 mm by core laboratory angiography measurement were excluded from analysis, the 12-month TLR rate was 10.1% in the Angiography group and 4.3% in the IVUS group (P=0.01, 95% CI, [-10.6% to -1.2%]). With a pre-stent angiographic stenosis of > or =70%, the TLR rate was lower in the IVUS group compared with the Angiography group (3.1% versus 14.2%; P=0.002; 95% CI, [-18.4% to -4.2%]).
Conclusions: IVUS-directed bare-metal stent placement results in larger acute stent dimensions without an increase in complications and a significantly lower 12-month TLR rate for vessels > or =2.5 mm by angiography and for vessels with high-grade pre-stent stenosis. However, for the entire sample analyzed on an intention-to-treat basis, IVUS-directed bare-metal stent placement does not significantly reduce the 12-month TLR rate when compared with stent placement guided by angiography alone. In addition, IVUS evaluation of adequate stent expansion is underutilized by experienced operators.