Over-expansion of drug-eluting stents in patients with left main coronary artery disease: An in vivo study

Objective We aimed to determine the capacity of drug-eluting stent (DES) over-expansion in left main coronary artery disease. Methods Left main interventions with the largest available DES platforms (4.0 mm) and post-dilation performed with large non-compliant balloons (≥ 4.5 mm) were included. Maximal stent diameter (mm) and area (mm2) were measured using post-intervention intravascular ultrasound (IVUS). Stent diameter and area were calculated with the balloon diameter and inflation pressure. The diameter and area expansion indices were defined as follows: maximal/calculated stent diameter and maximal/calculated stent area, respectively. Results Twenty-three consecutive patients were included. The maximal stent diameter was 4.40 mm (4.30-4.80 mm), and 22 of 23 patients showed a diameter expansion index greater than 0.90. The area expansion index was 0.862. The expansion index < 0.85 group had a significantly higher percentage of calcification ≥ 90° on IVUS than did the expansion index ≥ 0.85 group (72.7% versus 16.7%, P = 0.007). One stent fracture occurred during over-expansion and one ischemic event occurred during follow-up. Conclusions DESs with a nominal diameter of 4.0 mm can be effectively over-expanded in left main coronary artery disease. Achievement of predicted stent area can be affected by calcification.