Usefulness of intravascular ultrasound in preventing stenting of hazy areas adjacent to coronary stents and its support of support spot-stenting

The uncertain significance of hazy areas at the margins of coronary stents may lead to further, at times unnecessary, stenting. However, the risk of restenosis increases substantially when additional stents are deployed. We used intravascular ultrasound (IVUS) to identify the causes of hazy segments adjacent to stents. We identified 13 cases with hazy regions adjacent to coronary stents and 20 controls without hazy regions matched by age, gender, and vessel stented. Hazy regions were defined from the angiogram as reduced contrast density without a clearly defined intimal tear, dissection, thrombus, or stenosis (> 50%). IVUS images were obtained from the reference, stent, and hazy and control regions adjacent to the stent. Computerized planimetery was used to measure the vessel, lumen, and plaque cross-sectional areas (CSAs), the maximum arc of calcium, and the eccentricity ratio (minimum:maximum lumen diameter). There were no significant differences between hazy and control segments in the vessel, lumen, and plaque CSAs. All lumen CSAs were >4.0 mm2. Compared with control regions, the hazy regions had calcified plaque more often (69% vs 25%; odds ratio [OR] 6.75, 95% confidence intervals [CI] 1.82 to 25.0]) and more frequent intimal tears (23% vs 0%, OR 6.67, 95% CI 1.98 to 35.0). Haziness was particularly associated with calcified plaque and eccentric lumen (p = 0.037). Thus, haziness at the margins of coronary stents is often caused by calcified plaque. IVUS can differentiate calcified plaques from intimal tears and thereby obviate unnecessary stenting.