Resolute Onyx 2.0: A New Tool for Small Vessel Coronary Artery Disease

Small vessel coronary artery disease contributes to more than 30% of coronary interventions.^1-2 Previously, small vessel disease has been treated using stents with a diameter greater than 2.25 mm. Diseased, extra-small coronary arteries with diameters between 1.5-2.25 mm are encountered frequently and patients can be symptomatic.^3,4 Coronary artery bypass grafting can be successfully performed on arteries greater than 1.5 mm in diameter if these arteries are believed to supply important areas of the myocardium.⁵ Furthermore, diffuse small vessel disease and distal vessel disease are often seen in patients with multiple comorbidities, including renal dysfunction and diabetes, and patients usually benefit from complete revascularization.⁶ The Resolute Onyx 2.0 mm drug-eluting stent (DES) (Medtronic), which has been approved by the U.S. Food and Drug Administration⁷, adds a new treatment option for small vessel coronary artery disease patients.

Case Presentation

The patient is a 76-year old Asian female with past medical history of type II diabetes, hypertension, dyslipidemia, and coronary artery disease post 4-vessel bypass surgery in 2008 using a:

• Left internal mammary artery (LIMA) to left anterior descending artery (LAD);
• Saphenous vein graft (SVG) to posterior descending artery (PDA);
• Saphenous vein graft (SVG) to obtuse marginal (OM) branch; and
• Free right internal mammary artery (RIMA) graft to the circumflex artery.

She presented with unstable angina in 2010, and subsequent cardiac catheterization demonstrated severe 3-vessel disease. There was occlusion of the free RIMA graft, but the separate SVG graft to the OM and the PDA was patent, and the graft from the LIMA to LAD was patent. The circumflex was a small vessel and had severe, diffuse calcifications; the tightest stenosis was 90%. It was treated with a 2.25 mm x 16 mm Taxus stent (Boston Scientific) with a type I distal dissection due to the stent being unable to advance to the dissected area.

In 2012, a repeat angiogram for angina again demonstrated severe calcified small vessel disease with a patent prior stent at the mid circumflex. The venous bypass graft was patent except for the known-to-be occluded free RIMA graft. In 2016, due to unstable angina despite optimal medical therapy, a coronary angiography was performed that again demonstrated severe diffuse calcified 3-vessel disease with patent SVG grafts and a patent LIMA graft. No intervention was performed due to native vessel disease in extremely small vessels.

In April 2018, the patient presented with unbearable angina. Subsequent cardiac catheterization demonstrated patent prior SVG grafts and a patent LIMA graft. However, distal to the SVG to PDA anastomosis, the native PDA was small with severe diffuse disease. The proximal portion had a 90% stenosis (Figure 1, Video 1). Extreme tortuosity and calcification of the proximal subclavian artery prevented selective cannulation of the LIMA to the LAD. However, angiography did show a tortuous internal mammary artery (IMA) that was patent. Distal to the anastomosis, there was a 90-95% stenosis of a small LAD (Video 2).

The patient subsequently underwent stenting of the PDA through the SVG using a Judkins right (JR) 4 guide catheter with a Resolute Onyx 2.0 mm x 8 mm stent (Figure 2, Video 3).

The attempt to cannulate the IMA through the femoral approach using a 6 French guiding catheter was unsuccessful due to the calcification and proximal tortuosity of the left subclavian artery (Figure 3). Subsequently, the attempt to cannulate the LIMA through a left radial approach was unsuccessful due to extreme angulation of the LIMA takeoff. Both a 5 French IMA guide and a 6 French JR3.5 and JR4 guide catheter were attempted. With significant difficulty, a 5 French IMA guiding catheter was placed close to the LIMA takeoff through the femoral approach. A Runthrough wire (Terumo) was advanced into the distal LAD through the IMA (Figure 4). Extensive spasm of the LIMA was noted (Video 4). After the intra-LIMA nitroglycerin was delivered to the patient, a 2.0 mm x 10 mm Euphora balloon (Medtronic) was inflated to 14-18 atmospheres (atm) with expansion of the lesion at the native LAD. Then, with difficulty due to the calcification of the lesion and the lack of backup from the guide, a 2.0 mm x 8 mm Resolute Onyx stent was advanced into the lesion and subsequently deployed at 12 atm. The distal portion of the stent was dilated with a balloon distal to the stent at 6 atm and the proximal portion was dilated with the same balloon at 14 atm. After intra-LIMA nitroglycerin, final angiography demonstrated no residual stenosis (Figure 5, Video 5).

At 12-month follow-up, the patient remained free of chest pain during routine activity and she is no longer on anti-anginal medications.

Discussion

Due to technological advances, coronary artery revascularization has progressed tremendously over the past four decades. However, many areas remain challenging, such as small vessel, diffuse coronary artery disease found in patients suffering from diabetes and renal failure, or difficult-to-reach distal vessel disease.⁶ It is estimated that 65% of extra-small vessels are located in critical locations of the heart.⁸ The Resolute Onyx 2.0 stent offers interventionalists the ability to place a stent in these critical locations. In a clinical trial, the Resolute Onyx 2.0 stent was associated with low rates of target lesion failure and in-stent late loss, and zero stent thrombosis.⁷

Chronic total occlusions (CTOs) have been noted in nearly 20% of patients undergoing coronary angiography.⁹ In the last decade, percutaneous intervention of CTOs has gained more acceptance with improvements in guidewires, microcatheters, and reentry technology, as well as operator experience.¹⁰ However, the procedural success rate remains low, especially in CTOs located in heavily calcified and torturous vessels. In many cases, failure to achieve clinical success was due to an inability to deliver the stent. The Resolute Onyx 2.0 mm stent has been tested for deliverability.¹¹ With its capacity to expand to 3.25 mm, the Resolute Onyx 2.0 mm stent has proven to be a game-changer in helping us deliver the stent for success in the most challenging cases. 

Disclosures: The authors report no conflicts of interest regarding the content herein.

The authors can be contacted via Dr. Zhaowei Ai at zhaoweia8@gmail.com.

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