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Page 2 of 12 Sciahbasi et al. Vessel Plus 2023;7:19 https://dx.doi.org/10.20517/2574-1209.2023.22

[3]
left main stenosis, thrombotic lesions, chronic total occlusions, and heavily calcified plaques . These kinds
of lesions represent a tough challenge for operators in terms of procedural success, complications, and long-
[4]
term risk of restenosis . Recently, the feasibility and success of these complex PCI have been essentially
improved by the introduction of advanced techniques, approaches and adjunctive specific devices,
particularly for the treatment of severely calcified lesions.

CALCIUM: ELEMENT OF RISK FOR PROCEDURAL SUCCESS
A particular challenge faced by interventional cardiologists is the treatment of calcified lesions: moderate to
severe coronary artery calcifications (CAC) are documented in more than 30% of patients who underwent
coronary angiography and a severe calcification has been observed in up to 15% of procedures . CAC
[5]
increase exponentially among elderly people, especially those affected by diabetes mellitus and advanced
renal disease , and the presence of CAC is an independent predictor of adverse prognosis even after
[6]
[7]
multivariate Cox regression analysis . The presence of CAC hampers wires and device crossing, limits stent
apposition and expansion and alters drug delivery and elution by delamination of drug-eluting polymers on
drug-eluting stents , increasing early complications (perforations, dissections) and late adverse events (late
[8]
thrombosis, restenosis) compared with noncalcified lesions [9,10] .

Calcium quantification and distribution is a fundamental point of procedural planning , but coronary
[11]
angiography has some limitations in visualizing coronary calcium that is better detected by means of
invasive Intravascular imaging techniques such as IntraVascular UltraSound (IVUS) and Optical Coherence
Tomography (OCT) [12,13] . These techniques provide adjunctive data on distribution and thickness of the
calcified plaque.

CURRENTLY AVAILABLE TECHNOLOGIES TO MODIFY CALCIFIED PLAQUE
In severely calcified lesions, plain balloon angioplasty is seldom effective for lesion dilatation because the
lesion could be resistant to high-pressure dilatation (in case of circumferential calcification) or because the
balloon expansion is asymmetric towards the compliant vessel opposite the arc of calcium (in case of
eccentric calcification). To address this clinical need, different tools and devices have been tested: high-
pressure non-compliant (NC) balloon dilation, super high-pressure (OPN) balloon, cutting or scoring
balloons, atherectomy techniques (rotational, orbital), laser and intravascular lithotripsy (IVL) balloons. All
these devices have pros and cons, so the choice requires a careful lesion analysis and an individualized
planning of the interventional strategy.

NC, cutting, scoring and OPN balloons increase the rate of procedural success compared with compliant
balloons, but often, the force to disrupt calcium is insufficient to achieve vessel expansion. Besides their still
limited efficacy, the rate of peri-procedural complications such as dissection or perforation, is not
negligible .
[14]
More effective tools are debulking devices such as rotational and orbital atherectomy that allow to alter
plaque morphology, creating fractures in the calcified lesion and a path through uncrossable lesions by
other devices, increasing the probability of complete stent expansion with a high procedural success .
[8]
Particularly hard lesions can increase the risk of failure and/or incarceration of the burr (especially for
rotational atherectomy, which does not have the possibility of bidirectional advancement). Ideal lesions for
atherectomy are therefore serrated plaques with superficial calcification. Currently, their use is limited by
the need for a learning curve and by the rate of coronary complications that include myocardial infarction,
slow flow, flow-limiting dissection, distal embolization, and perforation. Furthermore, a randomised clinical
trial performed in patients with heavily calcified coronary stenosis failed to demonstrate the superiority of