Optical coherence tomography in an anomalous left circumflex coronary artery with stent thrombosis due to extrinsic compression in hereditary hemorrhagic telangiectasia: a case report

Introduction

Background

Anomalous left circumflex coronary artery (ALCx) is a congenital coronary anomaly (CCA) in which the left circumflex artery (LCx) arises from the right sinus of Valsalva (RSV) or from the proximal right coronary artery (RCA) (1). Three different types of ALCx can be distinguished: type I, with separate ostia for the RCA and LCx; type II, with a common ostium in the RSV for both the LCx and RCA; type III, in which the LCx arises as a branch of the proximal RCA (2). Although usually a benign and incidental finding, 20% of CCAs can cause ischemic manifestations, and some malignant variants can even lead to sudden cardiac death (1).

Hereditary hemorrhagic telangiectasia (HHT), also known as Rendu-Osler-Weber syndrome, is an autosomal dominant genetic disorder characterized by mucocutaneous and visceral telangiectasias leading to recurrent bleeding episodes (3). Despite this hemorrhagic tendency, several studies suggest that HHT may also be associated with a prothrombotic state, characterized by elevated levels of von Willebrand factor and factor VIII and reduced activated partial thromboplastin time (4,5). Management of acute coronary syndromes (ACSs) in patients with HHT therefore requires careful balancing of thrombotic and bleeding risks.

Rationale and knowledge gap

The role of ALCx in the risk of cardiovascular (CV) events remains debated. Although most ALCx variants follow a retroaortic course, several anatomical features of coronary anomalies have been associated with increased CV risk, including an interarterial course between the aorta and pulmonary artery, the presence of the so-called slit-like orifice, the length of the proximal narrowing vessel >22 mm and an angle at the take-off level <30° are considered risk factors for the development of CV events (6,7). In addition, ALCx could be unintentionally ligated or compressed during surgical procedures, such as aortic or valve replacement surgery (8) or during transcatheter interventions (9).

Objective

Despite these data, to our knowledge, no case reports in the literature have described, through intravascular imaging, extrinsic compression of the ALCx leading to acute myocardial infarction. We present this article in accordance with the CARE reporting checklist (available at https://jovs.amegroups.com/article/view/10.21037/jovs-2025-1-60/rc).

Case presentation

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent for publication of this case report, accompanying images, and the videos could not be obtained from the patient or relatives despite multiple attempts due to logistical difficulties after hospitalization; however, oral informed consent was obtained during a follow-up telephone interview.

This case deals with a 56-year-old man, affected by arterial hypertension, dyslipidemia, and HHT, with a clinical history of relapsing ACSs. The diagnosis of HHT was established in 2009 according to the Curaçao criteria, based on epistaxis (approximately 10 episodes per year), pulmonary arteriovenous malformations, and a positive family history. Unfortunately, information regarding genetic mutations was not available. The patient receives periodic iron supplementation and blood transfusions according to routine blood count results; the patient has not had thrombotic events before 2013. The first anterior ST-elevation myocardial infarction (STEMI) occurred in August 2013 and it was implanted a drug-eluting stent in the left main-left anterior descending artery. He received dual antiplatelet therapy (DAPT) with clopidogrel and aspirin for one year and then continued with single antiplatelet therapy with clopidogrel. Later, in December 2017, an implantable cardioverter-defibrillator was implanted for ischemic dilated cardiomyopathy with severe left ventricular dysfunction. In May 2019, we performed coronary angiography (CAG) because of ventricular arrhythmias, which documented good patency of the previously implanted stent and no critical stenosis in the other segments. Subsequently, in October 2023, he developed another STEMI due to a very-late in-stent thrombosis and an additional drug-eluting stent was implanted in the left main-left anterior descending artery axis and he was discharged with DAPT with clopidogrel and aspirin for chronic anemia and a high risk of bleeding. In January 2024, the patient was listed for heart transplantation for recurrent ventricular defibrillation and advanced heart failure.

The patient returned to our attention on 16 March 2024, presenting to emergency department for dyspnea on minimal exertion and constricting retrosternal chest pain radiating to the left arm. On physical examination, he had diffused crackles on lung auscultation, regular heart rhythm without murmurs, and no other relevant findings. Vital signs were: blood pressure 90/55 mmHg, oxygen saturation 89% on a Venturi mask delivering 24% oxygen at 4 L/min, respiratory rate 30 breaths per minute, and body temperature 36.5 ℃. Electrocardiography (ECG) showed sinus rhythm at 75 bpm with a known left bundle branch block. Transthoracic echocardiography (TTE) revealed a diffusely hypokinetic left ventricle with a left ventricular ejection fraction (LVEF) of 25%. At admission, the patient’s medical therapy included aspirin 100 mg once daily, clopidogrel 75 mg once daily, bisoprolol 1.25 mg twice daily, ivabradine 2.5 mg twice daily, sacubitril/valsartan 24/26 mg once daily, canrenone 25 mg once daily, vericiguat 2.5 mg once daily, empagliflozin 10 mg once daily, furosemide 25 mg three times daily, rosuvastatin 20 mg once daily, ezetimibe 10 mg once daily, and pantoprazole 20 mg once daily. High-sensitivity cardiac troponin I peaked at 49,905 ng/L (reference range, <34 ng/L); B-type natriuretic peptide was 1,372 pg/mL (reference range, <100 pg/mL); hemoglobin was 9.0 g/dL (reference range, 13.5–17.5 g/dL); platelet count was 303,000/µL (reference range, 150,000–400,000/µL); creatinine was 0.92 mg/dL (reference range, 0.74–1.35 mg/dL); prothrombin time was 58% (reference range, 75–120%). In conclusion, the clinical picture was compatible with a non-ST-elevation-ACS complicated by an exacerbation of heart failure.

The CAG was performed only after 4 days, after the patient had achieved good hemodynamic compensation with intravenous diuretics (continuous infusion of furosemide at 5 mg/h for 2 days) and vasodilators (continuous infusion of nitroglycerin at 0.03 µg/kg/min for 3 days), and severe anemia (minimum hemoglobin level of 7.3 g/dL) had been treated with blood transfusions. The procedure revealed a proximal thrombotic subocclusion of the LCx originating from the proximal RCA (Video 1). Percutaneous coronary intervention (PCI) was performed with manual thromboaspiration, predilatation with a 2.5 mm × 20 mm semicompliant balloon (10 atm), implantation of a 3.5 mm × 15 mm BioFreedom Ultra drug-eluting stent, no post-dilatation of the main vessel, and side branch balloon dilation with a 1.5 mm × 15 mm semicompliant balloon (18 atm), restoring optimal coronary flow (Video 2). Moreover, PCI was performed without intravascular imaging because the lesion was focal and no technical difficulties were anticipated, despite the presence of an ALCx. Given the high hemorrhagic risk of the patient related to HHT, the frailty, and the severe anemia, we maintain clopidogrel as P2Y12 inhibitor for DAPT with aspirin. After the PCI, the patients returned to the cardiac intensive care unit, where he remained stable and asymptomatic for 48 hours. After that, he complained of sudden chest pain, ECG showed ST-elevation in infero-lateral leads and TTE a corresponding akinesia with worsening ventricular function. After being intubated and sedated, a new, urgent CAG was made, exposing a partial acute thrombosis of the LCx DES (Video 3).

PCI with manual thromboaspiration was performed, followed by assessment for residual thrombosis using optical coherence tomography (OCT) (Video 4) with the Abbott Dragonfly™ OPTIS™ imaging catheter. OCT revealed satisfactory stent expansion and apposition, a minimal residual in-stent thrombotic component, and signs of extrinsic compression of the proximal LCx. Specifically, a focal and phasic narrowing of the first segment of the ALCx was observed, where the vessel assumed a “slit-like” oval shape (minimal lumen area 2.54 mm²), involving the proximal edge of the stent and resulting in the accumulation of multiple stent strut layers at that level (Video 4, Figure 1). The final results of the procedure were good patency of stenting with an optimal final flow [thrombolysis in myocardial ischemia (TIMI) III].

Figure 1 OCT imaging of the ALCx: (A,C) focal narrowing of the first segment of the ALCx (“slit-like” oval shape); (B,D) accumulation of multiple strut layers in the proximal edge of the stent. ALCx, anomalous left circumflex coronary artery; OCT, optical coherence tomography.

Despite the known hemorrhagic risk due to HHT, given the hypercoagulable state of the patient, we decided not to implant other stent, to escalate DAPT from clopidogrel to ticagrelor and to initiate a continuous unfractioned heparin infusion for the next 24 hours. Moreover, given the phasic nature of the extrinsic compression, we decided not to perform further balloon inflation. Afterward, the patient remained asymptomatic and hemodynamically stable, with no decrease in hemoglobin levels until discharge after two weeks of hospitalization. At discharge, echocardiography showed a persistently severely reduced LVEF of 30%, and no further modifications to medical therapy were made apart from DAPT.

During follow-up, the patient experienced no further episodes of thrombosis or ACS but required hospitalization for recurrent heart failure and underwent heart transplantation nine months after the index procedure (Figure 2). At the time of writing this manuscript, 24 months after the index hospitalization, telephone follow-up revealed that the patient was in New York Heart Association (NYHA) functional class I and had experienced no further hospitalizations for heart failure.

Figure 2 Timeline of the case report. There are reported the principal events regarding coronary angiography, PCI, ACSs, and follow-up. ACS, acute coronary syndrome; ALCx, anomalous left circumflex coronary artery; DAPT, dual antiplatelet therapy; HF, heart failure; LM-LAD, left main-left anterior descending; NSTEMI, non-ST-elevation myocardial infarction; PCI, percutaneous coronary intervention; SAPT, single antiplatelet therapy; STEMI, ST-elevation myocardial infarction.

Discussion

Key findings

We describe a case of ACS due to acute stent thrombosis of an ALCx that appeared extrinsically compressed on OCT in a patient with severely reduced LVEF and HHT. To our knowledge, this is the first reported case of STEMI involving an ALCx in which OCT demonstrated extrinsic compression in a patient with the challenging coexistence of high ischemic and bleeding risk.

Strengths and limitations

A major strength of this case is the use of OCT, which allowed detailed visualization of stent architecture and vessel morphology, identifying signs compatible with extrinsic compression. OCT provided important insights into the mechanism of the early stent thrombosis.

However, several limitations should be acknowledged. The mechanism of the first very late stent thrombosis, which occurred in October 2023 in a stent previously implanted in 2013 in the left main-left anterior descending artery axis, cannot be clarified because the CAG was performed at another hospital, intravascular imaging was not performed and detailed procedural data were unavailable. In addition, platelet function testing was not performed, and clopidogrel resistance cannot be ruled out. Moreover, prothrombin time was reduced, confirming the hypothesis of a chronic prothrombotic state in patient, but levels of von Willebrand factor and factor VIII had not been measured. Finally, although OCT allowed accurate assessment of lumen and stent structure, it could not visualize the full thickness of the vessel wall and therefore could not exclude the presence of an intramural course of the ALCx.

Comparison with similar researches

CV events related to anomalous coronary arteries originating from the opposite sinus of Valsalva are rare and are mainly associated with extrinsic compression by surrounding structures. Management should be individualized according to anatomical and hemodynamic characteristics. Surgical unroofing is recommended in cases with a long intramural course and documented hemodynamic significance, whereas coronary translocation or ostioplasty may be preferable when ischemia is present in the setting of a short or absent intramural segment. In patients with concomitant coronary artery disease involving the anomalous vessel, coronary artery bypass grafting (CABG) or PCI may be considered (10).

Treatment of lesions in an ALCx with extrinsic compression is uncommon because the most frequent course of this vessel is retroaortic, which is typically not subjected to compression by the great vessels (11). Nevertheless, several case reports have described PCI of an ALCx as the culprit vessel in acute myocardial infarction (12,13). Furthermore, technical challenges during PCI have been reported, including an increased risk of in-stent restenosis due to acute angulation of the anomalous vessel (14).

Explanation of findings

In our patient, the mechanism of the second, early stent thrombosis cannot be defined with certainty; however, OCT clearly demonstrated extrinsic vessel compression, which likely contributed to the event. In previous reports of extrinsic coronary compression assessed by OCT, characteristic findings include slit-like narrowing of the ostium or vessel tract in naïve compressed vessels (15) and the presence of multiple overlapping stent struts in cases of extrinsically crushed stents (16). In our case, both findings were observed, respectively in the naïve proximal segment and at the proximal edge of the ALCx stent.

Several mechanisms may contribute to stent thrombosis and should therefore be considered. Stent underexpansion and stent malapposition are well-known mechanical causes; however, OCT in our case showed satisfactory stent expansion and apposition, making these mechanisms less likely. Neoatherosclerosis represents another possible cause, although it is more commonly associated with late or very late stent thrombosis and was not suggested by OCT findings in the present case. Medication non-compliance may also contribute to thrombotic events; however, the second stent thrombosis occurred during hospitalization, when DAPT was administered under medical supervision, making poor adherence unlikely. Finally, clopidogrel resistance should be considered. In our case, antiplatelet therapy was escalated to ticagrelor, a more potent platelet inhibitor. We cannot rule out with certainty the presence of clopidogrel resistance, as platelet function testing was not performed. However, it should be considered that the patient had previously taken clopidogrel after coronary stent implantation, without developing acute thrombosis.

Although OCT provided detailed information about luminal and stent morphology, it could not assess the full vessel wall and therefore could not exclude an intramural course of the anomalous LCx (17). Intravascular ultrasound studies suggest that an intramural course may be characterized by intussusception of the proximal segment of the ectopic artery within the aortic wall, often associated with coronary hypoplasia and lateral compression of the intramural segment, particularly during systole (18).

Implications and actions needed

The coexistence of HHT and ACS represents a challenging clinical scenario because of the simultaneous presence of high bleeding and thrombotic risk. Previous reports have described the use of bare-metal stents to shorten the duration of DAPT (2); however, aggressive antithrombotic treatment may be necessary in the presence of severe ischemic complications. Available evidence suggests that antiplatelet and anticoagulant therapies can be used in HHT patients with acceptable safety, as most patients experience only worsening epistaxis rather than major bleeding complications (19).

Several alternative therapeutic strategies could also be considered in similar clinical scenarios. CABG might represent a potential option in cases of recurrent stent thrombosis; however, in our patient this approach was not pursued because the patient was already listed for heart transplantation, and the surgical risk was considered prohibitive due to severely reduced LVEF and chronic anemia. In addition, surgical correction of the anomalous coronary anatomy could theoretically be considered; nevertheless, given the patient’s listing for transplantation, it was deemed preferable to avoid additional thoracic surgery and reserve surgical intervention for the transplant procedure. The use of a covered stent could also be hypothesized as a strategy to counteract external compression; however, evidence supporting this approach in anomalous coronary arteries is limited. Finally, long-term anticoagulation might be considered in the presence of a suspected prothrombotic state; however, this option was weighed against the high hemorrhagic risk associated with HHT. In our case, escalation of DAPT from clopidogrel to ticagrelor was preferred, reserving anticoagulation as a potential alternative strategy in case of further thrombotic events.

Further research is needed to better understand the mechanisms of thrombotic events in patients with HHT and to optimize strategies for balancing hemorrhagic and ischemic risks in the treatment of myocardial ischemia.

Conclusions

ALCx is a very rare condition, usually not subject to compression by great vessels. Our case witnesses how such coronary anomaly may be associated with extrinsic compression of the vessel and possibly a stent, playing a role in the pathogenesis of ischemic events. This raises the question of the best treatment of a coronary lesion on an ALCx, especially when the thrombotic and hemorrhagic risks are simultaneously high.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://jovs.amegroups.com/article/view/10.21037/jovs-2025-1-60/rc

Peer Review File: Available at https://jovs.amegroups.com/article/view/10.21037/jovs-2025-1-60/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jovs.amegroups.com/article/view/10.21037/jovs-2025-1-60/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent for publication of this case report, accompanying images, and the videos could not be obtained from the patient or relatives despite multiple attempts due to logistical difficulties after hospitalization; however, oral informed consent was obtained during a follow-up telephone interview.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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