Intravascular lithotripsy for proximal cap ambiguity in percutaneous coronary intervention for chronic total occlusions: the “stone whisper” technique

A 74-year-old male with heart failure and left ventricular ejection fraction of 40% presented with exertional chest pain and dyspnoea. The patient had undergone percutaneous coronary intervention to the right coronary artery 12 years earlier following an inferior myocardial infarction. One year ago, they received an implantable cardioverter-defibrillator implantation as secondary prophylaxis after experiencing out-of-hospital cardiac arrest with no evidence of progression in the known one-vessel disease. Coronary angiography revealed a chronic total occlusion (CTO) in a large side branch of the left anterior descending artery (LAD) with a flush occlusion at the ostium of the CTO vessel (Moving image 1). The exact origin of the occluded vessel was unclear because of the flush ostial nature of the CTO, raising the possibility that it could be an intermediate or an early diagonal branch (Figure 1A).

Proximal cap ambiguity is typically addressed using retrograde wiring or intravascular ultrasound (IVUS)-guided cap puncture1. However, in this case, retrograde options were unavailable, and IVUS of the LAD failed to identify the proximal cap of the target occluded vessel because of...