Calcium-Modification Techniques in Calcified Coronary Artery Disease: A Systematic Review of Comparative Evidence on Procedural Success, Complications and Clinical Outcomes

Background/Objectives: Severe coronary calcification complicates percutaneous coronary intervention (PCI), and several calcium-modification technologies are available, but direct randomized comparisons are limited. We reviewed the comparative evidence on procedural success, complications and clinical outcomes. Methods: Comparative studies of coronary calcium-modification techniques during PCI that reported procedural, safety or clinical outcomes were eligible. PubMed and ClinicalTrials.gov were searched in May 2025 for records published from 1 April 2015 to 1 April 2025 (PROSPERO CRD420251077471; no external funding). We included 32 publications: eight randomized trials (10 publications) and 22 observational or descriptive studies. Evidence was organized in tiers and synthesized descriptively, without pooling, because definitions were heterogeneous and event rates were low. Risk of bias in randomized trials was assessed with RoB 2 where full texts were accessible. Results: Procedural success was generally high (usually 85–100%) and major complications were uncommon, but success definitions differed, and reported dissection (0% to over 80%) and slow-flow (0% to 31.6%) rates varied widely. Most comparative data were observational. In randomized comparisons, no device consistently outperformed another for procedural success, stent expansion or minimal stent area. Clinical outcome comparisons were limited by heterogeneous endpoints and low event rates. Risk of bias was rated from full texts for five out of the eight randomized trials, none at low risk overall; ratings for the others were provisional or not possible. Conclusions: The evidence is largely observational and of low certainty, and is insufficient to establish clinically meaningful differences among most technologies. Device selection should be lesion-specific and imaging-informed, and adequately powered head-to-head trials with standardized endpoints are needed.