Case presentation

A healthy and active 83-year-old woman without prior cardiac history presented with 1 week of intermittent chest pain, culminating in a prolonged episode of severe rest pain prompting hospital admission. In the emergency department, her initial electrocardiogram showed inferior T-wave changes, and she quickly became pain-free with nitrates, aspirin, a beta blocker, and unfractionated heparin. Subsequent serial troponin values peaked at 3.9 ng/mL. She was diagnosed with a non-ST segment elevation myocardial infarction. Her past medical history is notable only for hypertension, hyperlipidemia, and degenerative joint disease, and she lives independently. Her physical examination was unremarkable and her laboratory studies were notable only for a serum creatinine of 1.3 mg/dL. She was referred for cardiac catheterization.

Cardiac catheterization

Coronary angiography found no significant obstructive disease in the left coronary artery (Figure 10-1) but a severe ostial stenosis of the right coronary artery, with extensive calcification (Figure 10-2 and Video 10-1). Based on the angiogram, her physician decided to proceed with a percutaneous approach and, anticipating great difficulty because of the ostial location and the degree of calcification observed, the operator planned to debulk the lesion with rotational atherectomy.

FIGURE 10-1 This is the left coronary angiogram; there were no significant obstructive lesions noted.

FIGURE 10-2 The ostium of the right coronary artery was severely narrowed with heavy calcification noted around the ostium (arrow).

Femoral venous access was obtained and a temporary pacemaker wire positioned in the right ventricular apex. The operator then engaged an 8 French right Judkins guide catheter with side holes and administered eptifibatide as a double bolus plus infusion along with unfractionated heparin to achieve an activated clotting time (ACT) greater than 200 seconds. A floppy-tipped rotational atherectomy guidewire was positioned distally in the right coronary artery. Rotational atherectomy was accomplished first with a 1.5 mm burr, followed by a 2.0 mm burr. The angiographic result after rotational atherectomy is shown in Figure 10-3 and Video 10-2. The operator removed the rotational atherectomy guidewire and positioned a conventional 0.014 inch floppy-tipped guidewire distally in the right coronary artery. The lesion was dilated with a 3.0 mm diameter by 20 mm long compliant balloon and a 3.5 mm diameter by 23 mm long sirolimus-eluting stent positioned to cover the ostium (Figure 10-4 and Video 10-3) and postdilated with a 4.0 mm diameter by 9 mm long noncompliant balloon to high pressures. The final angiographic images satisfied the operator, although mild narrowing remained at the ostium (Figure 10-5 and Video 10-4); intravascular ultrasound was not performed and the procedure was terminated.

FIGURE 10-3 This is the angiographic result after rotational atherectomy with a 2.0 mm burr.

FIGURE 10-4 This figure demonstrates the position of the stent relative to the right coronary ostium.

FIGURE 10-5 Final angiographic results after stenting the right coronary ostial lesion.

Postprocedural course

The pacing electrode was withdrawn and the femoral sheaths removed using manual pressure when the ACT fell below 180 seconds. After an uncomplicated overnight stay, she was discharged the next morning on clopidogrel, aspirin, atenolol, atorvastatin, and lisinopril.

She remained symptom-free for 5 months, and then developed recurrent severe chest pain similar to her initial symptoms. She was again admitted to the hospital, but this time, serial troponins were negative. Repeat cardiac catheterization revealed severe, in-stent restenosis of the ostium of the right coronary artery (Figure 10-6 and Video 10-5). Her physician decided to treat this lesion percutaneously with a cutting balloon. Using bivalirudin as the procedural anticoagulant, the operator dilated the stenosis with a 3.5 mm diameter cutting balloon followed by a 4.0 mm noncompliant balloon to high pressures. Although the angiographic result appeared acceptable (Figure 10-7), there remained a gentle narrowing of the ostium. Intravascular ultrasound was performed and demonstrated excellent stent expansion distally (Figure 10-8), but the ostium remained deformed with a 7 mm² minimal lumen area, despite aggressive balloon dilatation (Figure 10-9). In order to treat this apparent recoil, the operator placed a 4.5 mm diameter by 13 mm long bare-metal stent and expanded it to high pressures (Figure 10-10). The angiographic result appeared much improved (Figure 10-11 and Video 10-6); importantly, the post-stent intravascular ultrasound images showed wide expansion of the stent at the ostium (Figure 10-12).

FIGURE 10-6 Angiogram obtained after the patient developed recurrent chest pain, showing severe in-stent restenosis (arrow).

FIGURE 10-7 Angiographic result obtained after treatment of the in-stent restenosis lesion with a cutting balloon and further high pressure dilatation with a noncompliant balloon. There remains mild narrowing of the ostium (arrow).

FIGURE 10-8 Distal to the ostium, the right coronary stent appears well-expanded.

FIGURE 10-9 At the ostium, there is deformity and underexpansion of the stent.

FIGURE 10-10 Bare-metal stent deployment at the ostium.

FIGURE 10-11 The angiographic appearance is much improved after repeat stenting of the ostium.

FIGURE 10-12 Following stent placement, the intravascular ultrasound showed improved expansion of the ostium.

She had an uncomplicated course following the procedure and enjoyed resolution of her symptoms. Unfortunately, 3 months later she again developed recurrent severe angina. When another catheterization confirmed recurrent, severe in-stent restenosis at the ostium, she was referred for a single-vessel bypass operation. She recovered uneventfully from this surgery and has remained asymptomatic during follow-up.

Discussion

Coronary artery disease is classified as “aorto-ostial” when it involves the left main or right coronary ostium, or “branch-ostial” when it involves the ostium of a large side branch such as a diagonal or obtuse marginal artery. Aorto-ostial disease is relatively uncommon; observed in less than 1% of patients with coronary artery disease. In addition to atherosclerotic heart disease, it is also seen in association with prior therapeutic chest irradiation, diseases of the aorta such as syphilitic aortitis and Takayasu arteritis, and with calcific aortic valve stenosis.

Percutaneous treatment of aorto-ostial disease presents several important technical challenges. First, the operator may find it difficult to accurately image the ostium by angiography, a critically important component of the procedure in order to ensure that the true ostium is covered by the stent. The true ostium is often obscured by the guide catheter, or from reflux of contrast in the aorta or by the sinuses themselves, making it very difficult for the operator to be confident in the placement of the stent. Second, aorto-ostial lesions are often calcified and rigid and subject to greater amounts of elastic recoil because the lesion involves the aortic wall and not just the coronary artery. Finally, there are often significant technical challenges associated with the choice of a satisfactory guide catheter. The operator needs to engage the artery with a guide that will allow adequate angiographic imaging and provide support for device delivery, but also allow the operator the ability to gently disengage the guide when positioning the stent at the ostium without resulting in the guidewire and stent catheter flying out of the coronary artery. The use of an extra-supportive guidewire may help stabilize the system, particularly with right coronary ostial lesions.

The acute technical success for percutaneous interventions of aorto-ostial lesions is very high, but restenosis rates are higher as compared to similar lesions that do not involve the ostium.¹ As demonstrated in this case, there is a high restenosis rate for right coronary artery ostial lesions as compared to left main stem ostial lesions; the mechanism, by intravascular ultrasound studies, appears to be stent recoil as well as neointimal formation.²

Some operators advocate pre-stenting rotational atherectomy or cutting balloon angioplasty to reduce the elastic recoil component, theoretically improving the long-term results for ostial lesions.³ Currently, there are little data and no randomized controlled data to support this strategy for the treatment of aorto-ostial lesions. This strategy did not appear effective in this case.

Similar to other lesion subsets, drug-eluting stents reduce the rate of restenosis for aorto-ostial lesions as compared to bare-metal stents.^4,5 However, as shown in this case, restenosis remains a significant problem.

Several important technical tricks may improve the operator’s success. Incomplete coverage of the ostium is the most commonly encountered mistake during treatment of these challenging lesions. This is often due to the previously mentioned difficulty in accurately imaging the true ostium by angiography. In addition, if the operator “overshoots,” causing an excessive length of the stent to protrude into the aorta, it may create difficulties with re-engagement later on. One trick to ensure coverage of the ostium involves the “stent tail wire” technique in which another 0.014 inch guidewire (the tail anchor wire) is placed alongside the stent catheter and inserted behind the last strut. The stent, along with the attached tail anchor wire, is advanced along the guidewire already in place in the coronary artery positioned in the ostium. The tail anchor wire does not enter the coronary artery, but instead straddles the aorto-ostium and helps identify the exact location of the aorto-ostium.⁶

It may not be enough to position the end of the stent flush with the ostium, since the final row of struts may not have adequate strength to resist the force of recoil, leading some experienced operators to state, “When you think you have covered the ostium, pull the stent back a bit further.” As noted above, however, the risk of this maneuver is to have an excessive amount of stent outside the coronary artery.

Intravascular ultrasound is helpful to assure that the stent has completely covered the ostium and that it has been fully expanded, and, in the opinion of the author, should be a part of all interventions involving aorto-ostial lesions. In the event that the ultrasound reveals excessive recoil resistant to repeat balloon inflations, a second stent may be necessary to provide adequate radial strength against the aorto-ostial wall.