Impact of calcium burden, lesion preparation, and lithotripsy on stent underexpansion in severely calcified coronary lesions - a substudy of the BALI trial.

In 30 seconds

This BALI trial substudy examined pre-stent OCT features associated with underexpansion in patients with severely calcified coronary lesions. Patients had been randomized to OCT-guided lesion preparation with or without lithotripsy; investigators related pre-stent imaging to spatially matched post-procedure stent area. Underexpansion, defined as stent area ≤80% of reference, occurred in 33.9% of patients (56/165). Greater embedded or nodular calcium and pre-stent area stenosis were associated with underexpansion. Lithotripsy increased fracture frequency and improved expansion at the site of maximal calcification compared with conventional preparation.

Key findings

• Underexpansion occurred in 33.9% of patients (56/165).
• Embedded calcium >270° (OR 2.8, p = 0.02), nodular calcium >90° (OR 4.1, p < 0.001), and pre-stent area stenosis ≥20% (OR 4.3, p < 0.001) were associated with underexpansion.
• In frames with calcium >270°, two or more fractures were associated with larger stent area increases of 0.6 and 0.7 mm 2 (p = 0.002, p = 0.01), respectively.
• Lithotripsy increased fracture frequency (OR 1.8, p = 0.004) and improved expansion at maximal calcification (relative risk 0.50, p = 0.01).

Why it matters

Severe coronary calcium can impede stent expansion, and this analysis links specific OCT features to that outcome. The findings suggest that calcium distribution, stenosis, and the presence of multiple fractures may help characterize lesion preparation before stenting. The randomized comparison also provides evidence that lithotripsy can increase fractures and improve expansion at the most calcified site in this study population.

What to keep in mind

This is a substudy of the BALI trial, and the reported associations between OCT features and underexpansion do not establish that those features cause the outcome.