A Rare Complication Unveiled: Ostial Left Main Stenosis Post SAVR—A Case Report

Abstract

Iatrogenic coronary artery obstruction is one of many life-threatening complications associated with aortic valve replacement. Although very few cases of ostial coronary artery occlusion following cardiac surgery are reported, the consequences can be catastrophic due to increased risk of mortality. Due to the rarity, prompt investigation and early management are crucial to manage this catastrophic sequelae. We report a case in which a 61-year-old female presented with acute coronary syndrome 4 months after surgical aortic valve replacement and was found to have 99% left main ostial coronary artery occlusion.

Introduction

Patients with a bicuspid aortic valve (BAV) tend to present with significant aortic stenosis (AS) 5 to 10 years earlier than those with trileaflet aortic valves, and surgical valve replacement is often indicated. ¹ Left main coronary artery (LMCA) stenosis is a rare and potentially fatal complication of aortic valve replacement. ² Ostial stenosis can occur in the LMCA or the right coronary artery (RCA). Coronary artery obstruction usually occurs intraoperatively or up to 6 months following surgery.^3-5 To prevent mortality from delayed coronary artery obstruction, having a high suspicion index in the right clinical context is important.

We present a case in which a 61-year-old female presented with Non-ST elevation myocardial infarction (NSTEMI) 4 months following surgical aortic valve replacement (SAVR) for severe aortic stenosis in the setting of a bicuspid valve. The patient was found to have 99% left ostial coronary artery occlusion despite a presurgical coronary angiogram revealing only mild coronary artery disease (CAD).

Case Presentation

A 61-year-old female with a medical history of BAV with severe stenosis who underwent SAVR with a 25 mm Edwards Inspiris valve via mini right thoracotomy 4 months prior presented to our hospital with crushing chest pain and radiation to the left arm. She has no complications following her cardiac surgery. Before her SAVR, her preoperative left heart catheterization showed minimal nonobstructive CAD. Her post-SAVR echocardiogram showed a normal ejection fraction of 55% with no wall motion abnormality.

On presentation, her physical exam was positive for tachycardia and bibasilar crackles on chest auscultation. High-sensitivity troponin peaked at 2586 ng/mL. Her EKG showed ST segment depressions in the lateral leads and poor R wave progression. Other pertinent laboratory findings included a positive COVID-19 test. She was started on aspirin and heparin infusion and admitted to the medical floor. An echocardiogram revealed an Ejection Fraction (EF) of 28% with global hypokinesis with akinesis involving the anterior, periapical, and anteroseptal walls. Her artificial valve was in place and functioning appropriately with no significant stenosis or regurgitation. Given her new LV dysfunction and elevated troponins, a decision was made to pursue left heart catheterization, although there were concerns that her symptoms might be indicative of myocarditis or Takotsubo cardiomyopathy. Left heart catheterization revealed 99% critical ostial left main stenosis and severe pressure dampening on catheter engagement (Figure 1). An intra-aortic balloon pump (IABP) was placed given the patient’s ongoing chest pain. The patient elected to transfer to a tertiary facility where she had the Aortic Valve Replacement (AVR) completed. She underwent a successful single-vessel coronary artery bypass graft (CABG) with left internal mammary artery (LIMA) to the left anterior descending artery (LAD) following a cardiopulmonary by-pass.

Figure 1.

Coronary angiogram demonstrating severe ostial stenosis of the left main coronary artery and a bioprosthetic aortic valve.

Discussion

Iatrogenic coronary ostial stenosis after SAVR is a rare but potentially life-threatening complication and usually occurs 1 to 6 months after AVR, if not intraoperatively, depending on the underlying mechanism of injury. ⁶ It is typically confined to the left main or RCA. The incidence of coronary ostial stenosis is generally low, ranging from 1% to 5% of SAVRs. ¹ Other studies have reported incidences of 0.2% to 1.5%.^6-8 While this complication is uncommon, it underscores the importance of careful surgical technique and vigilant postoperative monitoring to detect and manage such rare but potentially life-threatening complications, including myocardial ischemia, infarction, and ventricular tachyarrhythmias. The mechanisms hypothesized in coronary ostial stenosis depend on the timeline of symptomatology. An intraprocedural mechanical injury to the arteries during coronary perfusion cannulation can cause acute dissection or perforation, resulting in immediate intraoperative myocardial ischemia and infarction. Alternatively, delayed presentations of ostial stenosis that can occur months later remain poorly understood. ⁶

While there is a scarcity of studies specifically focusing on risk factors for coronary ostial stenosis after SAVR, several risk factors have been implicated based on clinical observations and retrospective analyses, surgical trauma and procedure-based complications during AVR may contribute to coronary ostial stenosis. ⁹ Procedure-based implications include a localized hyperplastic reaction caused by cardioplegia, the cardioplegic catheter itself dilating and injuring the coronary ostium, and uncommonly coronary thromboembolism.^8,9 Prosthesis sizing and positioning have proven to be risk factors for coronary ostial obstruction. However, intraprocedural and postprocedural complications were independent of the type of prosthetic valve placed. ¹⁰

Patient factors include advanced age, diabetes, hypertension, and preexisting CAD, which could predispose patients to ostial stenosis.^11-13 Anatomical variations in coronary artery anatomy such as anomalous coronary artery origins, severe atherosclerosis affecting the ascending aorta, ⁸ and coronary intimal hyperplasia. Despite the evidence, there is no single implicated mechanism, and the exact cause remains unclear. Risk factors predisposing patients to coronary ostial stenosis (COS) posttranscatheter aortic valve replacement include female gender, aortic root <30 mm, a low coronary ostial height less than 12 mm, previously placed surgical bioprosthesis and the type of valve used with a higher risk associated with balloon-expandable valves. The rationale behind these risk factors is the increased likelihood of displacing the calcified native aortic cusps over the coronary ostium post-transcatheter aortic valve replacement (TAVR). ¹⁴

Iatrogenic stenosis can present clinically as severe angina, ventricular arrhythmias, congestive heart failure, or sudden death. Initial symptoms usually present within 6 months. However, symptoms may present as late as 30 months post-SAVR. Coronary angiography remains the gold standard for diagnosis.^15,16 The ultimate goal is to revascularize the occluded coronary artery promptly to salvage viable myocardial tissue utilizing percutaneous techniques such as percutaneous coronary intervention (PCI) or CABG. In cases of cardiogenic shock where PCI is not an option, bridging with inotropic agents such as vasopressors, mechanical support devices such as left ventricular assist device or impellas, and IABP are essential to maximizing perfusion to the myocardium supplied by the occluded coronary.^16,17 In our case, the patient underwent a successful mini right thoracotomy aortic valve replacement (MIC-AVR) without the need for a full sternotomy and was separated from cardio-pulmonary bypass without difficulty or complications—cross clamp time (87 minutes) and total bypass time (127 minutes). Although our patient did not have most of the risk factors outlined above except for hypertension and hyperlipidemia, her presentation was felt to be due to a surgical complication.

The patient presented with typical anginal chest pain with electrocardiographic and biochemical evidence of ongoing ischemia as well as physical and echocardiographic signs of acute decompensated heart failure due to ischemic cardiomyopathy with a left ventricular ejection fraction of 28% by 2D Simpson biplane. She also presented within the expected interval post-SAVR (6 months). Given that her pre-SAVR coronary angiogram was only notable for minimal nonobstructive CAD her current presentation was felt to be due to a postprocedural complication. As discussed above the main priority is to emergently restore perfusion to the obstructed coronary artery and emergent coronary angiography revealed 99% critical ostial left main stenosis (Figure 1). Our patient required short-term mechanical circulatory support with an IABP to maintain coronary perfusion and a swan-ganz catheter for hemodynamic monitoring. She was transferred to a partnering institution for urgent coronary artery bypass grafting and underwent a successful re-operative coronary artery bypass graft with a skeletonized left internal mammary artery graft to the LAD, requiring minimal pressor support. She was discharged in stable condition with close follow-up with her primary cardiologist.

A major limiting factor in MIC-AVR is the restriction of the surgical field, which could lead to iatrogenic complications. ¹⁸ This emphasizes the importance of further observational studies to delineate uninvestigated risk factors of coronary ostial obstruction in MIC-AVR compared to conventional AVR.

The prognosis of left main coronary ostial stenosis following SAVR depends on various factors, including the severity of the stenosis, the patient’s overall cardiac function, timely diagnosis, treatment options, prompt management, and long-term follow-up. Overall, with timely diagnosis and appropriate management, many patients with left main coronary ostial stenosis following SAVR can achieve favorable outcomes. However, the prognosis can vary widely depending on individual patient factors and the specific characteristics of the stenosis, highlighting the importance of personalized management strategies and comprehensive cardiac care.

Conclusion

Coronary artery occlusion is a rare but potentially fatal complication after surgical aortic valve placement. Inadequate placement of valve prosthesis during aortic valve replacement can result in fatal coronary artery stenosis. Due to the dismal prognosis, early diagnosis and rapid restoration of coronary perfusion is critical. Therefore, vigilant awareness and immediate intervention are warranted to avoid such fatal consequences.