Hyperexpansion of coronary stents and clinical outcomes.

The complication rates and late clinical follow-up of patients who experience stent hyperexpansion have not been well studied. We designed this prospective study to evaluate the influence of stent hyperexpansion on clinical outcomes in patients with coronary artery disease. Patients who underwent coronary stenting were divided into 2 groups according to whether or not their stents hyperexpanded (defined as stent/artery luminal diameter ratio of > or =1.1/1.0 with no residual stenosis) during implantation. Clinical, angiographic, and procedural characteristics were evaluated at baseline, and clinical outcomes were analyzed in-hospital and at 1 year. The primary endpoint comprised 1-year major adverse cardiovascular events (MACE): death, myocardial infarction, and target-vessel revascularization. Clinical characteristics were not statistically different between patients with hyperexpansion (n=94) and those without (n=542; controls). The hyperexpansion group had significantly smaller mean target-vessel diameters and less severe stenoses; their stents were implanted at higher pressures (13.51 +/- 12.93; P=0.01); and they had higher balloon/artery ratios (1.07 U vs 0.99 U; P <0.0001) and higher aggressiveness scores (14.5 U vs 12.79 U; P <0.0001). Rates of angiographic success and in-hospital MACE were similar, although the hyperexpansion group more often had occlusions of large side branches (5.3% vs 1.5%; P=0.03). At 1 year, the groups had similar rates of MACE (10.8% vs 10.7%), including target-vessel revascularization (8.2% vs 6.5%). Multivariate analysis revealed associations between stent hyperexpansion and higher aggressiveness scores, higher balloon/artery ratios, and narrower target vessels; the hyperexpansion group also had more target-vessel large-side-branch occlusions. Hyperexpansion was not associated with lower rates of MACE.