Changes in reference vessel diameter in ST-segment elevation myocardial infarction after primary percutaneous coronary intervention: implications for appropriate stent sizing.

Background: Stents may be undersized during primary percutaneous coronary intervention (PCI) in ST-segment elevation myocardial infarction (STEMI), leading to higher rates of stent thrombosis. We sought to compare the reference vessel diameter (RVD) of the infarct-related artery before, immediately after, and at late follow-up after PCI for STEMI. We further investigated whether vessels treated with paclitaxel-eluting (PES) or bare-metal stents (BMS) behave differently with respect to RVD at follow-up.

Methods: From the HORIZONS-AMI trial, we identified 2,974 patients (3,589 lesions) with complete quantitative angiographic data for stent implantation (2,233 treated with PES and 741 treated with BMS).

Results: Considering all lesions, the median RVD was 2.87 mm (25th-75th percentile 2.54-3.22 mm) at baseline, 2.92 mm (2.58-3.28 mm) immediately post-PCI, and 2.88 mm (2.55-3.22 mm) after 13 months (1,197 patients; P = .001 pre vs post, P = .06 post vs follow-up, and P = .21 pre vs follow-up). There were no significant differences between the RVD for PES versus BMS at any period. The maximal stent or balloon size was 3.00 mm (3.00-3.50 mm) for both groups. There were no differences in RVD at baseline or post-PCI between patients with and without stent thrombosis.

Conclusions: Reference vessel diameter does not change substantially from baseline to follow-up, irrespective of stent type. Stent diameter was appropriate for vessel size. The RVD of patients with and without stent thrombosis was similar at baseline and post-PCI. Thus, the high rates of stent thrombosis after primary PCI for STEMI cannot be attributed to stent undersizing.