Intravascular Ultrasound Findings Associated With Hydrodynamic Contrast Recanalization (HDR) of Coronary Chronic Total Occlusions

Background: Hydrodynamic contrast recanalization (HDR) is a novel technique to facilitate wire crossing during chronic total occlusion (CTO) percutaneous coronary interventions (PCI). The mechanisms underlying HDR have not been fully described. Aims: To investigate the impact of HDR on plaque morphology and wire tracking during CTO PCI using intravascular ultrasound (IVUS) imaging. Methods: We identified 35 patients who underwent successful HDR and IVUS-guided CTO PCI at our institution between January 2023 and December 2024. We collected the following from IVUS images: wire position (intraplaque vs. extraplaque) within the CTO segment, plaque morphology, and evidence of vascular injury (intramural hematoma or dissection). Results: Immediate post-HDR IVUS images were available for analysis in all 35 patients. IVUS imaging revealed intraplaque guidewire crossing in 91% (n = 32) of cases. Intraplaque speckling, which we have termed the “Starry Sky” sign, was observed in 24 cases (68%), and intramural hematoma was found in 11 cases (31%). Four dissections were detected: two precluded direct distal wire re-entry necessitating the use of non-HDR techniques (94% technical success). The overall procedural success rate was 100%, and there were no PCI-related complications (perforation, myocardial infarction, or death). Conclusions: HDR is a novel CTO PCI technique that appears to facilitate intraplaque wire crossing without causing significant vessel injury. The presence of speckled plaque by IVUS is a unique feature of HDR that may suggest a mechanism underlying this technique. Additional studies are needed to confirm these findings.