This was a prospective single-center prospective registry to evaluate the safety and efficacy of OA in a non-surgical center in Portugal. All patients who underwent intended IVUS-guided OA between January and September 2023 were included. The evaluation of calcified lesions was initially based on the presence of radiopacities prior to contrast injection in angiography. Staged OA-facilitated PCI was performed in all cases and the presence of severe coronary calcification was confirmed by IVUS. The decision to use OA was left to operator discretion, without any specific inclusion criteria.

The Diamond Back 360 OA system is comprised of four main components (Figure 1), including: (1) a dedicated 0.012″ guidewire with a stainless steel core and nitinol coating (ViperWire; Cardiovascular Systems); (2) a 1.25 mm diamond-coated crown that is able to spin around its axis at two different pre-set speeds (80000 or 120000 rpm); (3) a power providing-pump; and (4) a dedicated lubricant solution (ViperSlide; Cardiovascular Systems) comprised of water, soybean oil, egg yolk phospholipids, glycerin and sodium hydroxide that is infused to the OA system to reduce friction between the OA device and the ViperWire.

Figure 1.

Orbital atherectomy Diamondback 360 system. Marketed as the Diamondback 360°, it has some similarities to RA in that it is comprised of a stainless steel burr with embedded microscopic diamond chips, which allow differential atherectomy by sanding. Unlike RA's circulate tip spinning on a central axis, the OA device is an eccentrically orbiting, diamond-coated crown that goes against the plaque by of axis rotation via centrifugal force. As such, OA is able to ablate progressively larger cross-sectional areas. The crown, unlike that of RA, has diamond ablation surfaces on both its distal and proximal portions and is capable of ablation in an anterograde and retrograde fashion, reducing the risk of entrapment. IV: intravenous; RA: rotational atherectomy; OA: orbital atherectomy

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The access site was left to the operator discretion, although they were incentivized to use the distal right radial artery. Temporary pacemaker insertion and atropine administration were also left at the discretion of the operator. Intravenous unfractionated heparin was administered at 100 U/kg to obtain a target activated clotting time >250 s. After obtaining standard angiography projections, the ViperWire was advanced to the distal segment of the target coronary artery and IVUS, using the Eagle Eye (Phillips Volcano, San Diego, CA, USA), was performed to determine lesion severity, length and proximal and distal landing zones. Balloon pre-dilatation was performed if the IVUS catheter was unable to cross the lesion. Direct OA without IVUS pre-evaluation was conducted if the lesion was deemed uncrossable or non-dilatable. The OA device was advanced using the ViperSlide feature, activated at the proximal edge of the target lesion and advanced back and forth at approximately 1 mm/s during 25–30 second intervals with a similar resting period in between. After performing OA, IVUS was repeated to evaluate adequate calcium debulking and to decide additional plaque preparation techniques. Stent selection and landing was made using IVUS co-registration. Device speed was set by default at 80000 rpm. In cases with particular high calcium burthen and whenever deemed necessary by the operator, the higher speed velocity could be utilized to obtain adequate luminal gain. Additional utilization of other calcium debulking modalities was left at the operator discretion, although they were incentivized to perform OA sanding at both velocities until no significant pitch differences were heard before other devices were considered. After stent implantation a final IVUS run was done to evaluate stent expansion and apposition and to exclude complications. Antithrombotic strategies were decided according to the European Society of Cardiology guidelines on myocardial revascularization and the update on dual antiplatelet therapy in CAD.9,10

Debulking success was defined as proper device functioning and a <50% residual stenosis severity in the target lesion after OA. Procedural success was defined as adequate stent implantation using the Optimal IVUS-guided PCI criteria: (1) minimal cross-sectional area >5.0 mm2 (or >90% of the distal reference lumen cross-sectional area; (2) plaque burden at the proximal and distal stent edges <50%; and (3) no edge dissection involving media with length >3 mm.11 The need for additional calcium debulking modalities was recorded. Procedural complications included no-reflow phenomena, dissection, perforation and side branch occlusion. Safety outcomes included early (30 day) cardiovascular or procedure-related death, myocardial infarction, myocardial injury and reintervention and classified as by the fourth universal definition of myocardial infarction.12

Continuous variables with normal distribution were expressed as mean and standard deviation. Categorical variables were expressed as absolute count and respective percentages. All statistical analyses were performed using commercially available software (SPSS 28.0, IBM).

Between January and September 2023, a total of 37 patients with 53 severely calcified vessels were treated with IVUS-guided OA-facilitated PCI. Clinical and angiographic characteristics of the study population are shown in Table 1. Median age was73 [68–78.5], 87.2% (n=33) were male. The majority of patients presented with chronic coronary syndromes (56.7%, n=21) and 16.2% (n=6) of patients had reduced left ventricle ejection fraction.

Procedural characteristics are shown in Table 2. Distal radial access was used most cases (54.1%, n=20). Guide catheter sheath size was 6Fr in 78.4% (n=29) of patients. Mechanical circulatory support was not used either upfront or in bailout in none of the cases. Transitory administration of inotropic and vasopressors were used in two patients. Median procedure time was 115 [84–150] minutes and median contrast volume utilization was 118 [93–160] mL.

Overall, 53 coronary arteries were treated with OA, including 4 (10.8%) lesions in the left main (LM), 29 (45.9%) left anterior descending (LAD) artery, 14 (26.4%) in the left circumflex (LCx) artery and 17 (32.1%) in the right coronary artery (RCA) (Table 3). Most lesions were classified as type C (60.3%, n=32). IVUS imaging was performed in all patients. All lesions were treated at the lower speed setting of 80000 rpm. A total of three lesions were treated with both 80000 and 120000 rpm.

Calcium debulking success was achieved in 48 lesions (90.5%), in the form of superficial sanding (86.7%, n=46) and fracture (47.2%, n=25). Figure 2 illustrates examples of superficial sanding and medial calcium fracture in one patient. In 26 (49.1%) lesions, additional calcium modification techniques were used, the majority of which were cutting balloon. Intravascular lithotripsy (IVL) was used in 4 (7.5%) lesions. Additional non-compliant balloon dilatation preceded stent implantation in all cases. A median 2.0 [1.0–3.0] stents were implanted per patient (mean diameter 3.12±0.45 mm and mean length 28.2±7.9). Procedural success was 97.3% as assessed by IVUS imaging (Table 4).

Figure 2.

Illustrative example of IVUS-guided, OA-facilitated PCI of a calcified RCA. A1: severe diffuse calcified lesion on the proximal and mid segments; B1: OA placed in the mid segment of the RCA and several advancements and retreatments were made; C1: final angiographic result after stenting from the mid-distal segment trough the ostium; A2: severe 360° calcified lesion of the RCA; B2: revaluation after OA showing adequate sanding (echo reverberations) and luminal gain; C2: final imaging after stenting showing overall good apposition and expansion. IVUS: intravascular ultrasound; OA: orbital atherectomy; PCI: percutaneous coronary intervention; RCA: right coronary artery

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Procedural complications occurred in 8.1% (n=3) of patients. A total of 11 clinical safety events occurred during 30 days of follow-up (Table 5), the majority were minor myocardial injuries, defined as high-sensitivity troponin T (hs-TnT) over the 99th percentile of the upper reference limit (URL) and major myocardial injury, defined as hs-TnT ≥5 times de URL. One patient suffered periprocedural myocardial infarction (Type 4a). A total of two patients had clinically manifest no-reflow phenomena. Both cases were in the context of acute coronary syndrome and poor left ventricular ejection fraction. One patient a particularly clinically severe no-reflow phenomena with cardiac arrest and need for mechanical ventilation and vasopressor support due to subsequent acute respiratory distress syndrome and died five days into hospitalization. No re-interventions were reported. One case of distal coronary perforation was reported due to distal advancement of a guidewire while retrieving a non-compliant balloon and was treated with fat embolization. No significant pericardial effusion occurred.