Coronary intravascular lithotripsy in contemporary practice: challenges and opportunities in coronary intervention

Abstract

Percutaneous coronary intervention (PCI) of calcified coronary arteries is associated with poor outcomes. Poorly modified calcified lesion hinders the stent delivery, disrupts drug-carrying polymer, impairs drug elution kinetics and results in under-expanded stent (UES). UES is the most common cause of acute stent thrombosis and in-stent restenosis after PCI of calcified lesions. Angiography has poor sensitivity for recognition and quantification of coronary calcium, thereby mandating the use of intravascular imaging. Intravascular imaging, like intravascular ultrasound and optical coherence tomography, has the potential to accurately identify and quantify the coronary calcium and to guide appropriate modification device before stent placement. Available options for the modification of calcified plaque include modified balloons (cutting balloon, scoring balloon and high-pressure balloon), atherectomy devices (rotational atherectomy and orbital atherectomy) and laser atherectomy. Coronary intravascular lithotripsy (IVL) is the newest addition to the tool box for calcified plaque modification. It produces the acoustic shockwaves, which interact with the coronary calcium to cause multiplanar fractures. These calcium fractures increase the vessel compliance and result in desirable minimum stent areas. Coronary IVL has established its safety and efficacy for calcified lesion in series of Disrupt CAD trials. Its advantages over atherectomy devices include ease of use on workhorse wire, ability to modify deep calcium, no debris embolization causing slow flow or no-flow and minimal thermal injury. It is showing promising results in modification of difficult calcified lesion subsets such as calcified nodule, calcified left main bifurcation lesions and chronic total occlusion. In this review, authors will summarize the mechanism of action for IVL, its role in contemporary practice, evidence available for its use, its advantages over atherectomy devices and its imaging insight in different calcified lesion scenarios.

Keywords: calcified coronary artery disease; calcified left main; calcified nodule; coronary IVL; intravascular lithotripsy; shockwave for coronary calcium.

Figure 1.

Proposed algorithm for approach to severely calcified coronary artery lesion.

Figure 2.

Imaging insight of IVL effect on circumferential coronary calcium. (a–e) Pre-IVL OCT and IVUS images showing 360° arc of calcium (asterixis) with their respective lumen areas. (f–j) Post-IVL increase in lumen areas and fractures in calcium arc (marked by arrows). (k–o) Post-PCI final MSAs and widening of calcium fractures (asterixis). IVL, intravascular lithotripsy; IVUS, intravascular ultrasound; MSA, minimal stent area; OCT, optical coherence tomography.

Figure 3.

IVL for coronary CN. (a–c) OCT pullback from LAD artery showing CN (asterixis) with their lumen areas. (c–e) Post-IVL OCT images at same anatomical level as that of pre-IVL showing increase in lumen areas and calcium fracture at apex (d) and at base (e, f) of the CN. (g–i) Post-PCI OCT cross sections with their respective MSAs. CN, calcified nodule; IVL, intravascular lithotripsy; MSA, minimum stent area; OCT, optical coherence tomography; LAD, left anterior descending; PCI, percutaneous coronary intervention.

Figure 4.

Use of intravascular lithotripsy in calcified LMBD. (a) Coronary angiography showing critical distal LMBD. (b, c) OCT pullback from LM to LAD revealed deep eccentric calcium in L and B modes. Both LAD and LCx were wired and IVL balloon sized 3.5 × 12 mm² was used to modify the deep calcium. (d) Post-IVL coronary angiography showed decrease in distal LM stenosis without slow flow, perforation, flow limiting dissection and LCx compromise. (e, f) Post-IVL OCT showed increase in distal LM luminal area (arrow) on L and B modes. A deep linear fracture was also seen in distal LM. (g) Post-PCI angiography showed significant reduction in distal LM residual stenosis without LCx compromise. (h, i) Post-PCI OCT showed increase in distal LM lumen area from 1.61 to 10.48 mm². IVL, intravascular lithotripsy; LMBD, left main bifurcation disease; LAD, left anterior descending; LCx, left circumflex; OCT, optical coherence tomography; B mode, brightness mode; PCI, percutaneous coronary intervention.