Practice Update: Cardiology

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COMMENT
By Joerg Herrmann MD
This 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
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,
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.
Dr Herrmann is Associate
Professor of Medicine,
Mayo Graduate School of
Medicine, Rochester,
Minnesota.
Optical Coherence Tomography
Characterization of Coronary Lithoplasty for
Treatment of Calcified Lesions
JACC: Cardiovascular Imaging
Take-home message
• 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 mm2. 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
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).
BACKGROUND The ShockwaveCoronary Rx Lithop-
lasty System (Shockwave Medical, Fremont,
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
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 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.
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