Endocarditis in an ESRD patient with severe mitral annular calcification
By Brian Jefferson, MD
Cleveland Clinic Foundation
Mitral annular calcification (MAC) is a common pathologic and echocardiographic entity. The risk of infective endocarditis in patients with MAC is increased compared to patients without MAC.
The patient is a 54 –year- old African American female with a history of end stage renal disease, hypertension, secondary hyperparathyroidism, and intravenous drug use. The patient presented to an outside emergency department with pyrexia, respiratory difficulty and mental status changes.
The patient had missed several episodes of hemodialysis and was found lethargic by her family. She was taken to the local emergency department. Vital signs were significant for a Temperature of 102.7, blood pressure of 97/65 mm Hg, heart rate of 120 and O2 saturation of 94% on 3 liters of oxygen. Physical examination revealed JVD, a hyperdynamic PMI with a holosystolic murmur heard best in the axilla, a LUE A-V fistula with a palpable thrill and bilateral lung rales. Chest radiograph revealed bilateral infiltrates. Her ECG showed sinus tachycardia with left ventricular hypertrophy. (Fig 1)
The initial therapeutic strategy included hemodialysis and empiric antibiotics with improvement in her symptoms. Two sets of blood cultures grew methicillin sensitive s. aureus. A transthoracic echocardiogram was obtained revealing severe LVH with cavity obliteration, RVH with severe impairment of function, RVSP of 80 mm Hg, and severe mitral annular calcification with severe mitral stenosis(MS) and severe mitral regurgitation (MR).(echo1,2 and 3) She was transferred to the Cleveland Clinic for further treatment.
Despite antibiotic therapy the patients hemodynamic status continued to decline. She required endotracheal intubation and a pulmonary artery catheter was placed to assist with management. Her initial pulmonary artery (PA) pressures were 96/55 mm Hg. Despite aggressive medical therapy she remained febrile and hypotensive
A transesophageal echocardiogram revealed a large mobile vegetation attached to the mitral valve.(echo 4, 5) She was taken to the operating suites where she was noted to have a large 2.3 cm vegetation that appeared to arise in mitral annular calcification and a large annular abscess resulting in AV separation. The vegetation was removed, the abscess drained and repaired with a pericardial patch, and the mitral valve was repaired. Post-operatively the patients PA pressures at extubation were 37/16. A post operative echo revealed severe global hypertrophy, with minimal TR.
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Mitral annular calcification (MAC) is a common and well recognized echocardiographic and pathologic finding consisting of degenerative change and calcification of the mitral apparatus. It results in a wide clinical spectrum of findings including mitral valve dysfunction, thromboembolism and infective endocarditis. 1, 2, 4 Conditions that increase wall stress, produce abnormal valve motion or have abnormal calcium/phosphorous metabolism have all been implicated in contributing to the pathogenesis. MAC is a common entity in various disease states including end stage renal disease, and hypertension. 1 In addition, it has a prevalence of 7% in hypertrophic cardiomyopathy. 4
Infective endocarditis of mitral annular calcification is uncommon. However, the anatomic derangement produced by MAC, with its calcified crags that can disrupt the endocardium, create an ideal milieu for bacterial adherence and proliferation. A prospective study of elderly patients with MAC demonstrated a higher incidence of endocarditis in patients with MAC (3% in patients with MAC vs. 1% in those without MAC). 1, 3, 5. Aureus was the most common etiologic agent. Involvement of the base of the mitral valve, especially the posterior leaflet, along with periannular and myocardial abscesses is common. 1
This patient had many risk factors for endocarditis besides injection drug use. Her symptoms became refractory to medical management. Surgical repair of her valve with removal of the vegetation restored pulmonary pressures to near normal and alleviated her severe tricuspid regurgitation, hemodynamic embarrassment was more acute in nature. Her underlying hypertensive heart disease and severe mitral annular calcification were thought to be related and a contributing factors to the development of her clinical situation.
Comments from Dr. Eric Topol:
Mitral annular calcification was originally thought to be a much more benign entity than it has played out to be. This case vividly demonstrates a gross vegetation superimposed on MAC, with presentation of sepsis and rapid deterioration. Although uncommon, endocarditis can present more subtly and the echo diagnosis can be difficult when there is no macroscopic evidence of a vegetation.
1. Fulkerson et al. Calcification of the Mitral annulus, Etiology, Clinical Associations, Complications and Therapy. Am J of Med. 66: 967-77
2. Nestico et al. Mitral annular calcification: Clinical, Pathophysiology, and Echocardiographic Review. American Heart Journal. 107: 989-996
3. Eicher et al. Mitral Ring Abscess Caused by Bacterial Endocarditis on a Heavily Calcified Mitral Annulus Fibrosis: Diagnosis by Multiplane Transesophageal Echocardiography. American Heart Journal. 131:818-820
4. Meltzer et al. Mitral Annular Calcification: Clinical and Echocardiographic Features. Acta Cardiologica. 35: 189-202
5. Schecter et al. Intramural Left Atrial Hematoma Complicating Mitral Annular Calcification. American Heart Journal 132: 456-458