Subjects who do not meet the randomized study inclusion and exclusion criteria, but meet the inclusion and exclusion criteria for the observational study may be enrolled in the observational study. The objective of the observational study is to assess the real-world acute performance of the Shockwave Medical Lithoplasty System in the treatment of calcified, stenotic, peripheral arteries.The observational study is a prospective, multi-center, single arm observational study for subjects who do not meet the inclusion/exclusion criteria of the randomized study. A maximum of 250 subjects at the same 50 sites will be enrolled in the observational study. Procedural success defined as residual stenosis <30% prior to DCB or stenting by angiographic core lab. Enrollment in the observational study is anticipated to last approximately 16 months. Subjects in the observational study will be followed through hospital discharge.