Background: Plaque characteristics associated with effective intravascular lithotripsy (IVL) treatment of calcification have not been investigated. This study identified calcified plaque characteristics that favor the use of IVL.Methods and Results: Optical coherence tomography (OCT) was performed in 16 calcified lesions in 16 patients treated with IVL and coronary stenting. Cross-sectional OCT images in 262 segments matched across pre-IVL, post-IVL, and post-stenting time points were analyzed. After IVL, 66 (25%) segments had calcium fracture. In multivariable analysis, calcium arc (odds ratio OR 1.22; 95% confidence interval CI 1.13–1.32; P<0.0001), superficial calcification (OR 6.98; 95% CI 0.07–55.57; P=0.0182), minimum calcium thickness (OR 0.66; 95% CI 0.51–0.86; P=0.0013), and nodular calcification (OR 0.24; 95% CI 0.08–0.70; P=0.0056) were associated with calcium fracture. After stenting, stent area was larger for segments with fracture (8.0 6.9–10.6 vs. 7.1 5.2–8.9 mm2; P=0.004).Conclusions: Post-IVL calcium fracture is more likely in calcified lesions with lower thickness, a larger calcium arc, superficial calcification, and non-nodular calcification, leading to a larger stent area.