Orbital atherectomy for the treatment of severely calcified coronary lesions: evidence, technique, and best practices

Figures & data

Table 1. CAC risk factors [1,7,10–12] and PCI adverse events due to CAC [5,13–27].

CAC risk factors
Smoking/tobacco use	Advanced age
Physical inactivity	Family history and genetics
Overweight and obesity	Chronic kidney disease
High blood cholesterol and other lipids	Male gender
High blood pressure	Caucasian
Diabetes mellitus
Metabolic syndrome
PCI adverse events due to CAC
Unsuccessful PCI due to un-dilatable lesions
Balloon ruptures
Vessel dissection during PCI
Vessel perforation or vessel rupture during PCI
Asymmetric, malapposed, and under expanded stents
Higher incidence of MACE
High frequency of restenosis and TLR
Higher incidence of peri-procedural MI
Increasing the likelihood of stent thrombosis
Reduced drug concentration and uptake into the vessel wall from DES

CAC: coronary artery calcification; DES: drug-eluting stents; MACE: major adverse cardiac events; MI: myocardial infarction; PCI: percutaneous coronary intervention; TLR: target lesion revascularization.

Table 2. Coronary atherectomy device comparison.

	Rotational atherectomy Rotablator	Coronary orbital atherectomy system (OAS) Diamondback 360 (Classic Crown)	Coronary laser atherectomy catheter ELCA
Mechanism of action	Rotational Diamond-tipped burr spins concentrically on the wire Atheroablation via sanding/abrasion	Orbital Eccentrically mounted diamond-coated crown uses centrifugal force to orbit, allowing for continuous blood flow during procedure Atheroablation via sanding/abrasion	Laser Multifiber laser catheters transmit ultra violet energy Photoablation (vaporization)
Clinical indication	A sole therapy or with adjunctive balloon angioplasty is indicated in patients with coronary artery disease who are acceptable candidates for coronary artery bypass graft surgery.	To facilitate stent delivery in patients with coronary artery disease who are acceptable candidates for percutaneous transluminal coronary angioplasty (PTCA) or stenting due to de novo, severely calcified coronary artery lesions. OAS is approved by the FDA for the treatment of de novo, severely calcified lesions in the coronary arteries.	A stand-alone modality or in conjunction with PTCA in patients who are acceptable candidates for coronary artery bypass graft surgery. Moderately calcified lesions In-stent restenosis of stainless steel stents Saphenous vein grafts
Technical features	Front-cutting, mono-directional burr	Diamond coated crown, bi-directional treatment	Over the wire and rapid exchange catheters
	Multiple burr sizes (8) 1.25–2.5 mm	1.25 mm classic crown orbits to treats larger diameter	Available with concentric and eccentric tip designs
	0.009”/0.014” tip RotaWire Guide Wires	0.012”/0.014” tip ViperWire® Advance Coronary Guide Wire	0.014” Guidewire
	Power source: Pneumatic system, requires console, foot pedal, and compressed gas supply; nitrogen tank or room air	Power source: Electronic; System able to be placed on the operating field connects to a specialized saline pump.	Power source: Spectranetics CVX-300® requires console and foot pedal
	Speed: ranging from 140 krpm – 180 krpm during treatment	Speeds: 80 krpm, 120 krpm	Adjustable laser energy settings

Table 3. Coronary orbital atherectomy system (OAS) mechanism of action and technique tips.

	Coronary OAS
Mechanism of action	Eccentrically mounted diamond-coated crown reduces coronary plaque while changing vessel compliance, enabling successful stent deployment. As the crown rotates and orbit increases, centrifugal force presses the crown against the lesion, reducing arterial calcium. Differential sanding allows healthy tissue to flex away. Minuscule particulates produced do not require embolic protection. Effective in a wide range of coronary vessel diameters. Continuous blood flow while orbiting minimizes the risk of thermal injury to the vessel.
Technical features	Diamond coated crown; bi-directional treatment 1.25 mm classic crown; orbits to treats larger diameter 0.012”/0.014” tip ViperWire Advance Coronary Guide Wire Power source: Electronic; System able to be placed on the operating field connects to a specialized saline pump. Speeds: 80 krpm, 120 krpm
Clinical indication	The Diamondback 360 Coronary OAS is a percutaneous OAS indicated to facilitate stent delivery in patients with coronary artery disease who are acceptable candidates for PTCA or stenting due to de novo, severely calcified coronary artery lesions.
Contraindications	The OAS is contraindicated when the ViperWire guide wire cannot pass across the coronary lesion or the target lesion is within a bypass graft or stent. The OAS is contraindicated when the patient is not an appropriate candidate for bypass surgery, angioplasty, or atherectomy therapy, or has angiographic evidence of thrombus, or has only one open vessel, or has angiographic evidence of significant dissection at the treatment site and for women who are pregnant or children.
Warnings/ precautions	Performing treatment in excessively tortuous vessels or bifurcations may result in vessel damage; the OAS was only evaluated in severely calcified lesions; a temporary pacing lead may be necessary when treating lesions in the right coronary and circumflex arteries; on-site surgical back-up should be included as a clinical consideration; use in patients with an ejection fraction of less than 25% has not been evaluated.
OAS Technique Tips	Maintain a traverse speed between 1 and 10 mm/s. Target a traverse speed of 1-3 mm/s to consistently remain within the 1–10 mm/s range. Orbital atherectomy is a time-dependent therapy. Traversing at 1 mm/s on low speed will provide more orbital gain than 10 mm/s on high speed (based on carbon block model system). Do not use a pecking motion as this will result in traversing faster than 10 mm/s. Maintain 1:1 motion between the crown and advancer knob. If loss of 1:1 motion occurs, slowly retract the crown and re-engage the lesion with slow forward movement.

Figure 1. Diamondback 360® coronary orbital atherectomy system (OAS) Classic Crown (1.25mm). (a) OAS device features. (b) Close-up view of the OAS crown, drive shaft, nose cone, and spring tip. (c) The physics of the OAS mechanism of action.

Table 4. Coronary OAS: ORBIT I and II results [38,45–51].

	ORBIT I	ORBIT II	Real-world OAS multicenter registry
Treatment Number of patients	OAS+DES 50	OAS+BMS/DES 443	OAS+BMS/DES 458
Dissection (%)	12^a	3.4^b	0.9
No reflow/slow flow (%)	0	0.9	0.7
Perforation (%)	2	1.8	0.7
Abrupt closure (%)	0	1.8	–
In-hospital MACE (%)	4	9.8	–
Cardiac death (%)	0	0.2	–
MI (%)	4	9.3^c	0.9^d
TVR (%)	0^e	0.7	0
Long-term follow-up	6 months	3 years^f (N = 33)	5 years^f (N = 33)	30 days	1 year	2 years	3 years	30 days
MACE at follow-up (%)	8	18.2	21.2	10.4	16.9	20.0	23.5	1.7^g
Cardiac death (%)	2	9.1	12.1	0.2	3.2	4.7	6.7	1.3^h
MI (%)	6	6.1	6.1	9.7^c	10.6^c	10.9^c	11.2^c	1.1
TVR/TLR (%)	–	–	–	1.4	5.8	8.1	10.2	0
TLR (%)	2	3	3	0.7	4.7	6.2	7.8	0

Data not reported (–).

^aDissection types A–C; ^bDissection types C–F; ^cCK-MB > 3X ULN; ^dPeriprocedural MI; ^eTLR; ^fPatients enrolled at single-center in ORBIT I study; ^gMACCE defined as all-cause death, MI, TVR, and stroke; ^hAll-cause death.

BMS: bare metal stent; DES: drug eluting stent; MACE: major adverse cardiac events; MI: myocardial infarction; OAS: orbital atherectomy system; TLR: target lesion revascularization; TVR: target vessel revascularization.

Table 5. Coronary OAS treatment algorithm – best practices and optimal technique.

Coronary OAS treatment algorithm
Obtain 6 Fr or larger arterial access using the physician’s preferred site
Use imaging (angiography, IVUS, OCT) to locate, visualize, and evaluate the coronary lesion
Wire the lesion and then exchange for the ViperWire, position to verify minimum of 10 mm of distance between OAD and guidewire tip during treatment
Prime OAD and (outside the body) perform momentary test spin, open brake, lock control knob, and leave pump on
Advance the OAD crown approx. 3-5 mm proximal to the lesion, unlock control knob
Engage OAD brake and start device on low speed, advance at a target of 1-3 mm/s
Use a series of intermittent treatment intervals with rest periods at least equal to the treatment duration until resistance and pitch change is steady
In non-tortuous vessels 3.0 mm or larger, high speed may be used at the operator’s discretion
Lock the control knob and remove the OAD

IVUS: intravascular ultrasound; OAD: orbital atherectomy device; OAS: orbital atherectomy system; OCT: optical coherence tomography.

Figure 2. Approach to lesion preparation for severely calcified coronary lesions.

Figure 3. OCT imaging with angiographic co-registration of coronary OAS treatment. Top row is OCT imaging; bottom row is angiographic co-registration. a and a’. Baseline image of calcified coronary lesion (white arrows) pre-OAS treatment. b and b’. Post-OAS image indicating calcified plaque modification (short white arrows). c and c’. Final image showing stent expansion and apposition.

Figure 4. OAS orbit/lumen diameter dependent on crown traverse speed, rotational speed, and number of passes.

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