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Page 12 of 22 Andò et al. Vessel Plus 2023;7:15 https://dx.doi.org/10.20517/2574-1209.2023.26

Excimer coronary LASER Atherectomy
Technical fundamentals of ELCA and preliminary studies
LASER is the acronym for “Light Amplification by Stimulated Emission of Radiation”. Laser energy is
produced when an active medium, excited by electrical energy, emits monochromatic coherent light. The
only approved system for coronary application is the excimer laser (CVX-300 ELCA System, Spectranetics
Inc., Colorado Springs, Colorado). Its laser unit uses XeCl (monochloride of Xenon) as the active medium
at a wavelength of 308 nm and generates a pulsed energy emission of up to 80 mJ/mm with a maximum
2
repetition rate of 40 Hz and width of pulse of 125-200 ns. This energy is called fluence. The system has a
5-min warm-up time and requires calibration. In contrast to the infrared laser, the excimer laser has very
limited penetration in terms of depth and ablates tissue very precisely without excessive heat generation,
minimizing unintentional tissue damage . Laser catheters are available as over-the-wire or rapid-exchange
[85]
devices and consist of fibers concentrically or eccentrically arranged. Catheter sizes can range from 0.9 mm
(5F compatible) to 1.4 mm (6F compatible) and 1.7 mm (7F compatible) and 2.0 mm (8F compatible). The
ratio of recommended laser catheter size to vessel diameter should not exceed 0.5-0.6. Since ELCA catheters
are contact lasers, the maximum external diameter of the tip defines the maximum lumen that can be
reached with a single pass. Excimer Coronary LASER Angioplasty (ELCA) was introduced several decades
ago as an alternative to balloon angioplasty and works by photo-ablating atherosclerotic plaques through
three main mechanisms : (1) photochemical, with the breaking of molecular bonds [86,87] ; (2) photothermal,
[85]
through an increase in the temperature of the intracellular water which causes cell breakage; and (3)
photomechanical, that occurs when the laser acts on a liquid medium (saline solution, contrast, blood) with
the generation of vapor bubbles at the tip of the catheter which, expanding and imploding, create micro-
cracks on the obstructing plaque which will then allow subsequent complete expansion of the balloon. Such
an effect is amplified when the laser acts directly on the contrast agent [88,89] . In summary, the mechanisms
leading to lumen enlargement and plaque dissection with ELCA appear to be plaque ablation and forced
vessel expansion .
[90]

The few randomized studies available, conducted over twenty years ago, have not demonstrated the
superiority of revascularization with ELCA compared to conventional PTCA of complex lesions. In the
multicenter AMRO study of 308 patients with stable angina, there was no difference in procedural success
(80% with ELCA vs. 79%) or net lumen gain on angiography (0.40 mm vs. 0.48 mm), moreover with a
transient occlusion rate 10 times higher (7% vs. 0.7%). At 6 months, there was a trend towards a higher
incidence of restenosis with laser (51.6 vs. 41.3%) . The ERBAC study compared PTCA with ELCA (as well
[91]
as rotational atherectomy) in 685 patients with stable angina . Procedural success rates were comparable
[92]
(77% and 80%) between the ELCA and PTCA groups, as were in-hospital complication rates (4.3% and
3.1%). At 6 months, the target vessel revascularization rate was significantly higher in the ELCA group
[92]
(46.0% vs. 31.9%) . In a meta-analysis of 16 trials and 9,222 patients treated with various percutaneous
interventional techniques, a significantly higher probability (OR 1.55, 95%CI: 1.09-2.20) of developing
[54]
restenosis with ELCA compared to conventional PTCA was also documented .

Current indications to ELCA
The results of the randomized studies and of the meta-analysis do not support the extensive use of the
ELCA, and since this is also a very expensive technology, its application remains limited to specific targeted
indications. Among them, a common indication for ELCA is the presence of calcific lesions that cannot be
crossed or dilated [93,94] , chronic total occlusions (CTO) that cannot be crossed with a micro-catheter,
intrastent restenosis and under-expanded stents , lesions with a high thrombotic burden in acute
[89]
myocardial infarction in addition to or as an alternative to conventional thrombectomy devices [95,96] . The
ELCA technique indeed permits the vaporization of thrombotic material, inhibits platelet aggregation, and
[97]
ablates the underlying atherosclerotic plaque . ELCA is now rarely used as a first-line strategy for highly