Practice Update: Cardiology

EDITOR’S PICKS 8

Optical Coherence Tomography Characterization of Coronary Lithoplasty for Treatment of Calcified Lesions JACC: Cardiovascular Imaging Take-home message

and laceration and dissections in others. Thus, the effect is more uniform and the device is safe; the only complications are related to dissections caused by the angi- oplasty component. All of this being said, the real effect and differential impact of this new technology cannot be judged until appropriate comparison studies are done. As the effect is largely an enhancement of balloon angioplasty effects, comparison with plain old balloon angioplasty would be the first step, then other plaque calcium-modifying strategies, such as the mentioned atherectomy options. Only then will we really know how useful of an adjunct this procedure is. The current data, however, are an important step in this direction. They provide the necessary feasibility and safety data to proceed. Coronary lithoplasty, here I come. Optical coherence tomography characteriza- tion of coronary lithoplasty for treatment of calcified lesions: first description. JACC Car- diovasc Imaging 2017 Aug 01;10(8)897-906, ZA Ali, TJ Brinton, JM Hill, et al. www.practiceupdate.com/c/56930 circumferential multiple fractures noted in >25%. The frequency of calcium fractures per lesion increased in the most severely calcified plaques (highest tertile vs. lowest tertile; p = 0.009), with a trend toward greater incidence of calcium frac- ture (77.8% vs. 22.2%; p = 0.057). Post-lithoplasty, mean acute area gain was 2.1 mm(2), which fur- ther increasedwith stent implantation, achieving a minimal stent area of 5.94 ± 1.98 mm(2) and mean stent expansion of 112.0 ± 37.2%. Deep dissec- tions, as part of the angioplasty effect, occurred in 13% of cases and were successfully treated with stent implantation without incidence of acute clo- sure, slow flow/no reflow, or perforation. CONCLUSIONS High-resolution imaging by OCT delineated calcium modification with fracture as a major mechanism of action of lithoplasty in vivo and demonstrated efficacy in the achievement of significant acute area gain and favorable stent expansion.

• Optical coherence tomography (OCT) findings were evaluated in 31 patients with severely calcified stenotic coronary lesions treated with lithoplasty prior to stent implantation. Intraplaque calcium fracture following lithoplasty was seen in 43% of lesions, and circumferential multiple fractures were seen in >25% of lesions. The most severely calcified plaques showed the highest frequency of calcium fractures per lesion. The mean acute gain in area after lithoplasty was 2.1 mm 2 and stent implantation increased this further to a maximal stent area of 5.94 mm 2 . Mean stent expansion was 112.0%. Deep dissection was seen in 13% of cases, and all were successfully treated with stent implantation. • The main mechanism of action of lithoplasty is to cause intraplaque calcium frac- tures and hence gain increased area, which facilitates stent expansion. Abstract

angle were not very prominent, even with 94 pulses on average. However, the goal is more the fragmenta- tion into pieces, or, better stated, fractures into the planes of coronary artery calcifi- cation. Calcium fractures were noted in nearly 50% of cases and circumferential multiple fractures in 25%. These numbers were not significantly increased by stent implantation. These observations may thus argue in favor of a lithotripsy effect and sufficient improvement of lesion com- pliance. Importantly, these effects were more pronounced with increasing calcifi- cation severity, and an effect was noted irrespective of depth within the vessel. This being said, OCT is not as sound as IVUS to visualize coronary calcifications, especially those of deeper location. Nevertheless, these are important dis- tinguishing features from the effects of rotational and orbital atherectomy, which cannot modify deep-seated calcium. In further distinction, lithotripsy does not pul- verize or abrade the plaque, with distal microembolization risk, or entail a guide- wire bias that leads to asymmetry and eccentricity of the effect in some lesions, California) delivers localized, lithotripsy-enhanced disruption of calcium within the target lesion (i.e., lithoplasty) for vessel preparation before stent implantation. METHODS We analyzed OCT findings in 31 patients in whom lithoplasty was used to treat severely calcified stenotic coronary lesions. RESULTS After lithoplasty, intraplaque calcium fracture was identified in 43% of lesions, with

COMMENT By Joerg Herrmann MD T his study is an important contribution even though only 31 patients were included. This is half the cohort of patients currently in the DISRUPT CAD program on a novel mode of percutane- ous intervention: coronary lithoplasty. The terminology is noteworthy. This is not litho- tripsy, which is pure shockwave therapy. It is lithoplasty; that is, with an element of angi- oplasty. Indeed, the coronary lithoplasty catheter is a balloon angioplasty cath- eter that contains a series of unfocused electrohydraulic lithotripsy emitters. The balloon is advanced to the lesion, inflated to 4 atm (to unfold), and 10 pulses are deliv- ered (ie, lithotripsy). This is then followed by further dilation to nominal pressures and reference vessel size (ie, angioplasty). The procedure is repeated for a mini- mum of 20 pulses. Of further note, OCT was performed before lithotripsy, requir- ing predilation in 20% of the cases. Given these elements of angioplasty involved, the acute gain in luminal dimensions can- not be attributed to lithotripsy effects alone. One may even argue that the modification effects on calcium thickness and calcium BACKGROUND The ShockwaveCoronary Rx Lithop- lasty System (Shockwave Medical, Fremont, OBJECTIVES This study sought to determine the mechanistic effects of a novel balloon-based lithoplasty system on heavily calcified coronary lesions and subsequent stent placement using optical coherence tomography (OCT).

Dr Herrmann is Associate Professor of Medicine, Mayo Graduate School of Medicine, Rochester, Minnesota.

PRACTICEUPDATE CARDIOLOGY