An Unusual Case of Pannus Formation - A Late Postoperative Complication of a Prosthetic Valve Replacement Causing Severe Cardiomyopathy

Case Report

Austin J Clin Cardiolog. 2021; 7(1): 1076.

An Unusual Case of Pannus Formation - A Late Postoperative Complication of a Prosthetic Valve Replacement Causing Severe Cardiomyopathy

Carreon AM¹*, Mohsin I¹, Watson B¹, Carter RN², Ponder M³ and Kramer K³

¹1Department of Internal Medicine, Norton Community Hospital- Internal Medicine Residency, Norton, United States

²Department of Cardiothoracic Surgery, Ballad CVA Heart Institute, Kingsport, United States

³Department of Cardiology, Ballad CVA Heart Institute, Kingsport, United States

*Corresponding author: Carreon AM, Department of Internal Medicine, Norton Community Hospital- Internal Medicine Residency, Norton, United States

Received: March 15, 2021; Accepted: April 02, 2021; Published: April 09, 2021


There are several well-known long-term complications following prosthetic valve replacement. Pannus formation is one of the rare complications whose estimated incidence varies between 0.3% and 1.3% per patient-year [1]. The exact etiology of pannus formation is unknown but histopathologically, pannus formation is due to fibroelastic hyperplasia that variably occurs after valve implantation [2]. The rarity and acute coronary syndrome like clinical presentation makes pannus formation a clinically important diagnosis during initial presentation. Workup preferably includes Transthoracic Echocardiography (TEE) with or without CT angiography. Management includes urgent or emergent surgical excision of the pannus with or without re-replacement of the aortic valve [1].

We present a 66-year-old female who presented with typical angina symptoms along with diffuse ischemic EKG changes five years after aortic valve replacement surgery with Trifecta Bioprosthesis due to severe aortic stenosis with Non-ST Elevation Myocardial Infarction (NSTEMI). Coronary angiography done on admission showed left main ostial stenosis of 90-95 % in proximity to the aortic valve prosthesis. A Transthoracic Echocardiogram (TTE) revealed an ejection fraction of 30-35 % with global hypokinesia but did not suggest any valve dysfunction. CT angiogram was done the next day which revealed a noncalcified plaque (pannus) greater than 75% occlusion in the left main in proximity of the aortic valve. Despite expedited care and surgical evaluation, unfortunately the patient decompensated in the surgical operating room and did not survive.

Keywords: Pannus formation, Prosthetic aortic valve


For patients who have severe aortic valve dysfunction, aortic valve replacement is recommended for preservation of left ventricular function, relief of symptoms, and patient survival [3]. The choice of prosthetic heart valve type should be a shared decision-making process. A mechanical valve has an advantage of being durable and long lasting while a bioprosthetic valve undergoes Structural Valve Deterioration (SVD) after six to eight years after implantation. However, mechanical valves are highly thrombogenic and require life-long anticoagulation therapy. Hence, bioprosthetic valves are preferred in patients with high risk of bleeding [4,5]. Age is important because incidence of SVD in a bioprosthetic valve is greater in young patients, while the risk of bleeding from prescribed anticoagulation post mechanical valve implantation is higher in older patients. Hence american heart association recommends bioprosthetic valves in patients of any age whom anticoagulants are contraindicated (class Ia). It is reasonable to implant an aortic mechanical valve for patients of age less than 50 years who can tolerate long term anticoagulation (class II a) and a bioprosthetic in aortic valve replacement is reasonable for patients of age more than 70 years (class II a) [5,6].

Occurrences of 30-day mortality after aortic valve replacement have been documented at approximately 2.5%. Early complications include: atrial fibrillation, high grade AV block with pacemaker implantation, renal failure requiring dialysis, stroke, and endocarditis [7]. Pannus formation is an uncommon but serious complication of prosthetic valve replacement. It is one of the two causes of structural acquired Prosthetic Valve Obstruction (PVO), the other being thrombus formation. It is likely due to fibroelastic hyperplasia which occurs over time and usually restricts normal leaflet motion [8]. There are currently no guidelines for preventing pannus formation since it is usually a complication of chronic underlying processes [9]. The incidence varies from 0.73% in bi-leaflet valves to 1.8% in tilting disc valves and occurs in both mechanical and bioprosthetic valves [1,10]. The timeline for occurrence ranges from days to over 5 years, with an average of 24±26 months. Echocardiography is the main diagnostic test to evaluate prosthetic valve function and regular follow up is standard of care [1].

Case Presentation

In 2015, a 66-year old female underwent a 19 mm Trifecta bioprosthetic Aortic Valve Replacement (AVR) secondary to severe calcified aortic stenosis. Significant medical history includes hypertension, hyperlipidemia, and hypothyroidism. She presented to the emergency department at an outside facility with complaints of intermittent chest pain consistent with typical angina that was graded severe, pressure type, mid sternal in location, and radiated throughout the chest wall. She acknowledged a history of smoking, illicit drug abuse, and chronic narcotic dependence. The patient had poor compliance and no follow-up after AVR. Physical examination was unremarkable, S1-S2 normal. EKG revealed sinus rhythm with subtle ST segment elevation in AVR, V1 and diffuse ST segment depression in multiple leads concerning left main/multivessel CAD (Figure 1). Troponin levels were 1.88 with a repeat value of 2.37 on serial measurements. The patient was given ticagrelor, aspirin, heparin, metoprolol, and nitroglycerine paste, and referred to our hospital for expedited cardiac evaluation.