A 79-Year-Old Man with a History of Ischemic Heart Disease Presenting with Right Coronary Artery Aorto-Ostial Stent Deformity and Restenosis: A Case Report

Introduction

Coronary artery disease (CAD) is a very common condition that frequently requires management in the form of percutaneous intervention with stent placement [1,2]. Most frequently, atherosclerotic lesions occur beyond the ostium of the main coronary vessels, while aorto-ostial coronary artery disease is infrequently encountered (approximately 1.5% of cases) [3]. Female sex, hypertriglyceridemia (left coronary artery), radiation, and family history of CAD (right coronary artery) are independent risk factors for aorto-ostial CAD [4]. Involvement of the right coronary artery (RCA), either as a solitary ostial lesion, or as part of bilateral coronary artery involvement, has been observed in 41% and 9%, respectively, of ostial disease [5]. Management of ostial disease is similar to that for non-ostial CAD for the most part, with major adverse events also being similar [6].

Complications associated with stents can be divided into procedural complications and stent-related complications [7,8]. Coronary stent-related complications are failure of deployment, stent thrombosis (acute, subacute or late), stent infection, and coronary artery aneurysm [8–10]. Examples of procedural complications are coronary perforation, device embolization, and longitudinal stent deformity [7]. Longitudinal stent deformity is a complication encountered more frequently with newer generations of stents [11]. The major mechanism of longitudinal stent deformity is due to attempts to pass secondary equipment and guide-catheter damage (85%) and is associated with complex coronary lesions, such as vessel calcification (26%), tortuosity (25%), long lesions (28%), and ostial disease (21%) [12].

Aorto-ostial stenting can be challenging due to a multitude of factors, such as anatomic variability, increased recoil related to significant elastic tissue content, and poor guide-catheter support [13]. In the case of the RCA, the non-tubular anatomy of its ostium makes it prone to geographic miss after deployment, with higher rates of restenosis and need for repeat intervention [14–16]. Although a minimal degree of protrusion into the aorta is required to ensure adequate ostial coverage [16], stent placement with increased aortic overhang can result in difficulties with subsequent catheter engagement or guidewire access. The combination of complex anatomy, limitations of two-dimensional (2D) angiography, and possible pathological factors such as extensive disease or calcification can result in geographic misses in 54% to 80% of cases [15,17].

In-stent restenosis (ISR), defined as greater than 50% stenosis within or immediately adjacent to the stented segment, is a complication that developed with the advent of bare-metal stents (BMS), and to a lesser degree can also occur in drug-eluting stents (DES) [18]. Its incidence ranges from 17% to 41% for BMS [19], with a significantly lower incidence of 5% to 10% for DES [20]. Risk factors associated with ISR can be patient-related (diabetes, renal insufficiency), coronary lesion-related (lesion complexity, length, diameter, location), or procedure-related (stent positioning, stent under-expansion, stent fractures) [18]. Although coronary angiography is the main modality of ISR evaluation [21], the use of intravascular ultrasound and optical coherence tomography can provide additional data for lesion characterization and to guide therapy [22,23]. Treatment modalities include balloon angioplasty, vascular brachytherapy, debulking techniques, bare metal stenting, use of drug-coated balloons, and drug= eluting stenting, with the latter 2 offering better outcomes [24].

Aorto-ostial ISR is a subset of coronary lesions, for which evaluation and treatment strategies are often underrecognized [25], and with a higher reported incidence than for other ISR lesions [26]. For example, RCA ISR incidence was reported to be 7.5% to 12.5% [27,28]. Percutaneous management is often challenging, with obstacles such as cannulation, guidewire advancement, and stent placement, although successful cases have been reported [29].

Thus, management of ostial RCA disease entails a multitude of anatomical, procedural, and device factors that can result in various complications and their combinations. We present the case of an elderly man with a history of aorto-ostial RCA CAD, who presented with acute coronary syndrome. During further evaluation, ISR, protrusion, and deformity were encountered, with a subsequent decision to pursue coronary artery bypass grafting and surgical removal of the stent. The location of CAD, coupled with the stent complications, led to an uncommon presentation of acute coronary syndrome.

Case Report

We present the case of a 79-year-old man with past medical history of coronary artery disease status after percutaneous intervention (PCI) with placement of multiple stents in the RCA 5 years prior to the current presentation. Other significant past medical history included heart failure with mildly reduced ejection fraction (44%), hypertension, hyperlipidemia, left bundle branch block (LBBB), chronic kidney disease, and diabetes mellitus. He presented with acute-onset chest pain, dizziness, and dyspnea. On initial evaluation, vitals were notable for a heart rate of 50 to 60 beats per minute; otherwise, his examination was unremarkable, without evidence of shock physiology, fluid overload, or pulmonary congestion.

Initial electrocardiography (ECG) (Figure 1) revealed sinus bradycardia with first-degree atrioventricular block, ST-segment depressions, and T-wave inversions in inferior leads, as well as ST-segment elevations in leads V1–V2, likely due to left ventricular hypertrophy.

Laboratory evaluation was notable for creatinine 2.38 mg/dL, which was his prior baseline; otherwise, chemistry including liver function tests, thyroid-stimulating hormone, and complete blood count were unremarkable. Troponins, although elevated, displayed a flat pattern at 105 ng/L to 100 ng/L (normal range <12 ng/L). Hemoglobin A1c was 10.1%.

Chest X-ray did not show evidence of acute cardio-pulmonary issues, while a computed tomography (CT) angiography scan of the chest and abdomen was without acute aortic abnormalities.

The patient’s presentation was most consistent with acute coronary syndrome, given acute-onset chest pain, ECG changes, and evidence of myocardial injury. The type I non-ST-elevation myocardial infarction (NSTEMI) in a setting of partial occlusion, involving branches of the left coronary artery (LCA) or distal right coronary artery, may explain the pathophysiological process behind the patient’s presentation. Additionally, type 4b or 4C NSTEMI in a setting of RCA stent thrombosis or stenosis could also be suspected. Unstable angina was also part of the differential, given the flat pattern of troponins on presentation, coupled with poor clearance in a setting of decreased renal function. Finally, we also considered non-ischemic conditions, such as musculoskeletal pain, gastro-esophageal disease, and anxiety attack.

Transthoracic echocardiography was notable for a left ventricular ejection fraction of 44% with mild diastolic disfunction and paradoxical septal motion (consistent with LBBB). The right ventricular size and function were within normal limits.

Given his acute coronary syndrome (ACS), he was administered aspirin and started on a heparin drip and morphine for pain control. Given his symptomatic improvement, hemodynamic and electrical stability, no signs of acute decompensated heart failure, history of chronic kidney disease, and intravenous contrast administration on admission, a decision was made to proceed with noninvasive in-patient ischemic evaluation.

Gated myocardial single-photon emission computed tomography (SPECT) revealed moderately depressed global left ventricular systolic function with severe inferior wall hypokinesis and paradoxical septal motion. A pharmacological stress test with regadenoson was notable for large sized, moderate intensity, and a partially reversible mixed perfusion defect in basal-to-apical inferior wall, predominantly consistent with scar tissue.

The patient was discharged home with a plan for outpatient elective coronary angiography, which subsequently revealed significant left anterior descending (LAD) disease in its middle segment, with positive diastolic hyperemia-free ratio (DFR) of 0.48 and associated 80% ostial disease of the 2nd diagonal branch. Moreover, evaluation of the RCA showed severe ISR with a large portion of proximal stent (Figure 2) protruding into the ascending aorta and a partially crushed stent in the proximal RCA, likely resulting from the first procedure. The degree of stent protruding into the aorta made cannulation exceedingly difficult, so intravascular imaging could not be performed. Together with inferior wall hypokinesis, the RCA findings were the probable culprit lesion leading to the patient’s acute coronary syndrome.

Given his history of diabetes mellitus, two-vessel CAD involving LAD and RCA, as well as evidence of RCA stent displacement the decision was made to proceed with coronary artery bypass graft (CABG) with removal of the ostial stent. Conservative management was considered but was deferred given the distribution of coronary artery disease and stent-related complications. He underwent successful bypass of the LAD using a left-internal mammary artery graft and of the RCA using a reversed left greater saphenous vein graft. The ostial stent was removed via transverse aortotomy and displayed longitudinal deformity in its mid-portion (Figure 3). Additionally, due to severe internal carotid artery disease, concomitant carotid endarterectomy was performed. The patient was successfully transferred to the intensive care unit for postoperative management.

Discussion

We describe a relatively uncommon case of ostial coronary artery disease, with complications that are usually associated with RCA ostial disease [28]. The newer-generation stents provide enhanced deliverability and opportunity for placement in tortuous or heavily calcified vessels [30]. Several stent characteristics, such as flexibility in crimpled or deployed state, trackability, scaffolding, radio-opacity, longitudinal and radial strength, and recoil, are considered during stent design. While enhancing flexibility may improve a stent’s deliverability, other attributes may be affected by stent design [12,30].

In our case, the ischemic chest pain may have been caused by either RCA or LAD disease, or quite possibly both. The RCA exhibited typical ISR with evidence of a marked longitudinal deformity resulting in severe foreshortening, giving it a crushed appearance.

The increased elastic recoil of the RCA ostium in combination with the limitations of 2D angiography and the technical aspects of newer-generation stents may have led to mechanical damage to the stent and subsequent ISR. It would be difficult to accurately reconstruct the timeline of events leading to the current presentation, as the patients’ medical care, including placement of the RCA stent, was outside of the United States and there was limited access to previous medical records. As there was an excessive amount of stent left in the aortic root, advancement of the stent was likely precluded due to kinking and marked foreshortening of the stent during the initial procedure, and it was likely just left in place at that point.

Similar presentations with challenging but successful percutaneous treatment have been described [29]. Despite multiple attempts, RCA cannulation and intravascular imaging proved extremely difficult in our case, and subsequent attempts at revascularization could not be made. Nevertheless, the patient’s past medical history of diabetes and multivessel CAD with LAD involvement meant he was a candidate for CABG [1], which would mean that even with successful RCA canulation and detailed evaluation of RCA anatomy and intravascular physiology, the management would not be significantly different. Moreover, he was also able to benefit from concomitant surgical management of carotid artery disease with endarterectomy.

Technological advancements in stent design make artery distribution- (RCA vs LCA) and ostium-specific stent designs available with newer-generation stents, and may lead to practice changes regarding invasive management of CAD based on distribution.

Conclusions

We report a rare but important complication of the use of coronary artery stents, particularly when used in the region of the RCA ostium, and discuss the approach to management of stent deformity and restenosis.