The IVL balloon catheter, available in diameters of 2.5 to 4.0 mm for coronary applications, is carefully sized to match the vessel’s reference diameter in a 1:1 ratio. This sizing ensures intimate contact with the arterial wall, maximizing acoustic wave transmission into the calcified tissue. Before use, the device is prepared by flushing it with a 50:50 saline-contrast mixture, which serves as the conducting medium for shockwave generation. Thorough air removal is critical to ensure optimal energy transfer. Once positioned across the calcified lesion, the balloon is inflated to 4 atm to achieve vessel wall apposition, facilitating efficient acoustic coupling to calcified tissue. Each cycle delivers 10 pulses at a frequency of 1 pulse per second (1 Hz). Earlier generation platforms (e.g., Shockwave C2) deliver up to 80 pulses, whereas newer-generation platforms (Shockwave C2+) allow delivery of up to 120 pulses for treating longer lesions. Following shockwave delivery, the balloon is inflated to 6 atm to promote symmetrical expansion, an indicator of successful calcium disruption, before deflating. However, many operators choose to deflate immediately after delivering pulses at 4 atm to reduce the risk of balloon rupture. In all cases, careful balloon deflation after each pulse sequence restores blood flow (avoiding ischemia), allows for dissipation of heat generated during lithotripsy, and clears cavitation bubbles, as residual air can reduce the efficiency of subsequent pulses. To ensure removal of residual air bubbles, some operators, in addition to deflating the balloon, aspirate residual air between cycles using syringes. These steps ensure consistent energy delivery and preserve optimal balloon performance, while the controlled frequency and pressure protocol maximize therapeutic efficacy without compromising procedural safety. Although the hallmark of IVL is effective calcium modification at low balloon pressures, ensuring adequate vessel compliance before stent delivery remains critical. In practice, many operators perform a brief adjunctive inflation with a noncompliant (NC) balloon, either before or after stent implantation, to confirm luminal expansion or optimize stent apposition.

Imaging with intravascular ultrasound (IVUS), optical coherence tomography (OCT), and micro-computed tomography consistently demonstrates the effectiveness of IVL. ^, These imaging modalities reveal distinct longitudinal and circumferential calcium fractures, validating the technology’s capacity to tackle complex calcified morphologies. Such fractures increase luminal area, facilitating more successful vessel preparation. OCT findings from the DISRUPT CAD III study (n = 100) illustrate IVL’s effect on calcified lesions and stent expansion. Pre-procedural minimal lumen area was 2.2 ± 0.8 mm², increasing to 6.5 ± 2.1 mm² post-IVL and stent placement, with final stent expansion reaching 78.4 ± 25.8% at the site of minimal stent area (MSA). Notably, fracture width widened significantly after stent deployment, underscoring IVL’s role in facilitating vessel preparation. Figure 2 illustrates OCT images before and after IVL, followed by stent implantation, demonstrating these fracture patterns and their impact on lesion preparation. These imaging findings provide direct mechanistic confirmation of IVL-mediated calcium modification and support the use of intravascular imaging to guide lesion preparation and stent optimization in heavily calcified lesions.

OCT-guided PCI using IVL for a severely calcified left anterior descending lesion : Preprocedural OCT images (A, B, C) reveal mixed calcium morphology: concentric calcium (A, B) and eccentric calcium (C) in the proximal to mid-left anterior descending artery, with a maximum thickness of 1.0 mm and a minimum lumen area of 2.1 mm ². Post-IVL OCT (A′, B′, C′) demonstrates multiple calcium fractures involving within both concentric and eccentric calcium as well as an intimal dissection at the edge of the eccentric calcium (B′, 6 O’clock). Final post-stent OCT (A″, B″, C″) revealed a well-expanded stent with calcium fractures behind the stent struts, without evidence of edge dissection or stent malapposition, achieving a minimum stent area of 8.1 mm ². OCT = optical coherence tomography; IVL = intravascular lithotripsy.

CNs represent a particularly challenging subset of CCL, characterized by protruding calcific masses that may lead to stent underexpansion, reprotrusion, and adverse clinical outcomes. CNs are a specific type of heavily calcified lesion that protrudes into the coronary artery lumen, causing a convex shape to the luminal surface. CNs can be either eruptive or noneruptive type, distinguished by a disrupted versus intact fibrous cap, respectively. CNs are associated with suboptimal stent expansion and high procedural complexity, often requiring multiple calcium-modifying strategies to achieve optimal outcomes. Although eruptive CNs are more deformable and may allow greater stent expansion, they paradoxically exhibit higher rates of target lesion revascularization.

IVL is increasingly used for calcium modification and demonstrates comparable efficacy in both eccentric (≤180°) and concentric (>180°) calcific lesions, with similar anatomical (luminal gain and stent expansion) and physiological (OCT-based fractional flow reserve, quantitative flow ratio, and index of microcirculatory resistance) results, as well as a favorable safety profile. ^,,, In cases with CNs, IVL has proven effective in generating fractures within the dense calcific matrix and enhancing vessel compliance. Despite CNs often bearing a higher calcium burden, pooled analyses from the DISRUPT CAD trials show that acute luminal gain and MSA remain on par with non-nodular lesions, with an even greater number of post-IVL fractures in CNs. ^, Comparative data have shown that IVL achieves similar procedural and clinical outcomes to RA and OA in CNs, with no significant differences in MSA or 1-year target vessel failure rates.

However, achieving adequate calcium modification in CNs may require additional IVL cycles or adjunctive use of high-pressure NC balloons. The introduction of newer generation IVL catheters with increased pulse delivery capabilities may further enhance treatment of these complex lesions, reflecting continued technological evolution. The ongoing prospective randomized NODULE-SHOCK trial (NCT07000045) is specifically designed to compare calcium-modification strategies in CNs and is expected to provide evidence to refine procedural selection and sequencing in this challenging lesion subset.

Aorto-ostial lesions present unique challenges in PCI due to their proximity to the coronary origin, elastic recoil, and the risk of dissection extending into the aorta. These lesions are often heavily calcified, making adequate calcium modification crucial for achieving optimal stent expansion and reducing restenosis rates. IVL has become a particularly suitable modality for balloon-crossable aorto-ostial lesions, offering a uniform circumferential modification of CAC. Recent data have demonstrated comparable technical success and long-term outcomes for IVL-treated aorto-ostial lesions relative to non-aorto-ostial calcified lesions, highlighting its safety and efficacy. IVL’s low rates of dissection and vessel injury are particularly relevant in ostial lesions, in cases where aortic dissection and guide catheter trauma are recognized concerns with atherectomy; however, direct comparative studies are lacking.

IVL offers a compelling solution for calcified bifurcation lesions, addressing both main and side branch calcifications without the risk of plaque shift or side branch compromise often seen with atherectomy. A key advantage of IVL is its ability to maintain dual wire access, a common limitation with RA and OA. In addition, the same IVL balloon can be used sequentially in similarly sized main and side branches, potentially reducing procedural cost. While no dedicated trials focus solely on bifurcation lesions, DISRUPT CAD IV reported that 34.4% of the treated lesions were bifurcations, achieving high procedural success with no instances of no-reflow. ^, Additional real-world data from the BENELUX-IVL registry reinforce these findings, showing IVL use in bifurcation disease to be associated with similar high procedural success and low 1-year MACE rates as compared to non-bifurcation lesions, with low rates of side-branch compromise, supporting its safety and feasibility in this challenging anatomy.

CCL with severe CAC is often associated with stent underexpansion, which is a strong predictor of ISR, contributing to restenosis and thrombosis in up to 42% of cases. Stent underexpansion arises from inadequate lesion preparation during initial stent implantation, with calcification behind the stent struts being the primary culprit. This unyielding calcium compromises stent deployment, leading to turbulent blood flow, impaired drug delivery, and recurrent restenosis. Traditional approaches to address stent underexpansion, such as high-pressure balloons, are often inadequate and carry significant risks of vessel dissection or perforation. Although IVL is used off-label in this setting, it has emerged as promising tool for treating stent underexpansion caused by calcified plaque. By delivering acoustic energy through a low-pressure balloon, IVL fractures calcium behind the stent struts, enabling optimal stent expansion while minimizing trauma to the vessel wall. This “stent-through” technology has been validated through multiple registries and clinical experiences. Real-world registries, such as SMILE and CRUNCH, have demonstrated procedural success rates of 87% to 92% with substantial increases in MSA and no IVL-related complications in underexpanded stents, a population traditionally considered refractory to treatment. ^, Similarly, a meta-analysis of 13 studies involving 354 patients found that IVL achieved an 88.7% success rate in stent underexpansion cases, with minimal procedural complications (1.6%).

Notably, recent data suggest that the efficacy of IVL may differ depending on the nature of calcification in ISR. In cases when stent underexpansion is primarily driven by calcium located behind the struts (calcified stent underexpansion), IVL is highly effective at achieving luminal expansion. However, in calcified neoatherosclerosis, in cases where calcium is located within the previously implanted stent, luminal expansion may remain suboptimal despite IVL treatment. In a single-center study comparing calcified neoatherosclerosis with calcified stent underexpansion, the suboptimal expansion rate was significantly higher in calcified neoatherosclerosis cases (56.3% vs 27.5%; p =.04). These findings may reflect lesion complexity rather than a true limitation of IVL, highlighting the need for further studies to clarify IVL’s role across the heterogeneous mechanisms of ISR. Evidence also indicates that IVL is less effective in cases when multiple stent layers are present, as overlapping struts attenuate shockwave energy and reduce the capacity to achieve optimal expansion. In the IVL-DRAGON registry, procedural success fell to ∼73%, with multilayer stents emerging as an independent predictor of IVL failure. Similarly, pooled analyses confirm that outcomes are consistently better in single-layer stents compared with multilayer ISR. In addition, IVL’s mechanism is specific to calcified plaque, and stent underexpansion due to fibrotic or scar tissue is largely resistant to shockwave therapy, necessitating alternative approaches.

IVL has emerged as a valuable tool for addressing calcified LMCA lesions, which pose unique challenges due to their critical anatomical and functional importance. The efficacy of IVL in this setting has been supported by recent data, including a multicenter analysis of 184 patients with calcified LMCA lesions treated with IVL-assisted PCI. This study demonstrated a technical success rate of 99.4%, with post-PCI imaging confirming calcium fractures in 82.4% of cases. Notably, MSA increased significantly, from 4.1 ± 1.3 mm² pre-treatment to 9.3 ± 2.5 mm² post-PCI, with a direct correlation between IVL balloon size and final MSA (p = 0.002). In-hospital MACE occurred in 4.4% of cases, rising to 8.8% at 30 days, with troponin-positive myocardial infarction identified as the sole independent predictor of adverse events. To optimize procedural tolerance during IVL treatment of LMCA lesions, several technical strategies are recommended. Electrocardiographic changes should be closely monitored during balloon inflation to detect early ischemia. Shorter inflation cycles of typically 5 pulses per inflation with 10-second perfusion rest periods between cycles maintain distal myocardial perfusion and minimize ischemic burden. Should hemodynamic or ischemic changes develop after balloon deflation, the device should be withdrawn into the guide catheter to restore coronary perfusion until hemodynamic stability is achieved. Lastly, high-risk patients such as those with reduced left ventricular function should be considered for mechanical circulatory support during LMCA IVL to facilitate tolerance of ischemic intervals. ^,

The ability of IVL to address eccentric calcium and modify CNs further enhances its applicability to LMCA lesions. ^, In a multicenter registry study, IVL demonstrated high technical success in treating calcified LMCA lesions, even in high-risk settings such as distal bifurcations and left ventricular dysfunction. A recent meta-analysis further reinforced these findings, confirming IVL’s feasibility and safety in calcified LMCA disease across multiple studies. By facilitating simultaneous calcium modification in both the left anterior descending and circumflex arteries while preserving guidewire access, IVL offers a distinct advantage over atherectomy. Its ability to achieve controlled calcium disruption without the risk of distal embolization or stent scaffold damage underscores its efficacy in managing the complexities of calcified LMCA disease. While early data demonstrate IVL’s high technical success and safety in LMCA interventions, its use demands meticulous pre-procedural planning with intravascular imaging to optimize lesion preparation and stent deployment.

Over 50% of CTOs exhibit moderate-to-severe calcification, and this remains a crucial component of CTO complexity scores. In the setting of CTO PCI, IVL has emerged as a valuable tool for modifying heavy calcification to facilitate stent delivery and optimization. Registry data and early case series have demonstrated high technical success and safety rates in cases when IVL is utilized (with or without concomitant RA) for lesion preparation after successful guidewire crossing. ^, Beyond standard plaque modification, recent reports have also described a novel application of IVL to facilitate proximal cap penetration in uncrossable lesions. In this “side-branch IVL” technique, IVL is delivered in a side branch adjacent to the proximal cap to modify its compliance, thereby enabling subsequent wire penetration. However, current data remains limited, and further investigation along with device innovation is needed to fully define the role of IVL in CTO interventions.