Caseous MAC Multimodality PDF

JACC: CASE REPORTS VOL. 3, NO. 1, 2021 ª 2021 THE AUTHORS. PUBLISHED BY ELSEVIER ON BEHALF OF THE AMERICAN COLLEGE OF CARDIOLOGY FOUNDATION. THIS IS AN OPEN ACCESS ARTICLE UNDER THE C...

JACC: CASE REPORTS VOL. 3, NO. 1, 2021 ª 2021 THE AUTHORS. PUBLISHED BY ELSEVIER ON BEHALF OF THE AMERICAN COLLEGE OF CARDIOLOGY FOUNDATION. THIS IS AN OPEN ACCESS ARTICLE UNDER THE CC BY-NC-ND LICENSE (http://creativecommons.org/licenses/by-nc-nd/4.0/). MINI-FOCUS ISSUE: IMAGING CASE REPORT: CLINICAL CASE SERIES The Spectrum of Caseous Mitral Annulus Calcifications Agnes Mayr, MD,a Silvana Müller, MD,b Gudrun Feuchtner, MDa ABSTRACT Mitral annular calcification (MAC) is a chronic, degenerative condition of the fibrous mitral annulus, which may transform to liquefaction necrosis MAC, a rare variant of caseous MAC. We present a series of experiences, showing the varying manifestations of caseous MAC according to multimodal imaging. (Level of Difficulty: Intermediate.) (J Am Coll Cardiol Case Rep 2021;3:104–8) © 2021 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/). C aseous mitral annular calcification (CMAC) is a rare variant of degenerative mitral annular calcification (MAC). It primarily affects older patients with hypertension, with an echocardio- a dynamic course of the condition, with conversion processes from MAC to CMAC and vice versa. Some of these cases are associated with histories of chronic kidney disease and hemodialysis treatment (1,4,5). graphic prevalence of 0.6% of all MACs and an overall Differentiation of a CMAC from other cardiac prevalence of up to 0.07% in the general population masses attached to the mitral annulus may be chal- (1,2). Due to the general benign prognosis, conserva- lenging due to its variable imaging characteristics tive management of this lesion is performed in most depending on its stage of evolution. Using only a cases. However, CMACs may grow large in size and single imaging modality such as echocardiography is infiltrate adjacent territories such as the myocardium. often not sufficient for a clear diagnosis. Therefore, a CMAC rarely was linked to severe mitral valve multimodal imaging approach is normally used; that dysfunction, transient aortic outflow tract obstruc- is, echocardiography, cardiac CT imaging, and cardiac tion, embolization, heart block, or constrictive peri- magnetic resonance (CMR). Echocardiography as carditis (3). Furthermore, echocardiographic as well first-line modality assesses the mass as well as the as computed tomography (CT) observations suggest functional significance of the CMAC. On both trans- thoracic echocardiography and in particular trans- esophageal echocardiography, a CMAC can be LEARNING OBJECTIVES recognized as a well-defined, echo-dense mass with
To familiarize with the clinical entity of central echolucency surrounded by a calcified enve- CMACs. lope at the posterior periannular region of the mitral
To train imaging characteristics of CMACs in valve (6). In addition, cardiac CT imaging confirms different modalities. this calcified nature of CMACs, revealing a variable
To recognize atypical imaging presentations hyperdense mass, with a central hypodense content of CMACs. and peripheral calcifications without enhancement From the aUniversity Clinic of Radiology, Medical University Innsbruck, Innsbruck, Austria; and the bUniversity Clinic of Internal Medicine III, Cardiology and Angiology, Medical University Innsbruck, Innsbruck, Austria. The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center. Manuscript received April 19, 2020; revised manuscript received September 15, 2020, accepted September 24, 2020. ISSN 2666-0849 https://doi.org/10.1016/j.jaccas.2020.09.039 JACC: CASE REPORTS, VOL. 3, NO. 1, 2021 Mayr et al. 105 JANUARY 2021:104–8 Caseous Mitral Annulus Calcifications whereas late gadolinium enhancement depicts ABBREVIATIONS F I G U R E 1 Dynamic Evolution and Atypical Location of a a peripheral rim of enhancement (8). AND ACRONYMS Caseous Mitral Annular Calcification Peripheral calcifications and avascularity CMAC = caseous mitral annular are key features in CMACs. These features can calcification be used to differentiate CMACs from other CMR = cardiac magnetic mass-like lesions involving the atrioventric- resonance ular grooves but lacking calcifications, such CT = computed tomography as myxoma, papillary fibroelastoma, MAC = mitral annular myocardial abscess, infective endocarditis calcification and vegetations, lipomatous hypertrophy, or TAVI = transcatheter aortic dilated coronary sinus (9). They can also be valve intervention used to differentiate from lesions that are well vas- cularized, such as myxoma, hemangioma, dilated coronary sinus or left circumflex artery aneurysm, and enlarged lymph nodes. Distinctions here can easily be accomplished by using color Doppler or contrast enhancement in CT imaging or CMR. How- ever, myocardial abscess within the annular region with an echo-dense appearance and systolic blood flow by color Doppler can closely resemble a CMAC, which may explain the first descriptions of CMACs as a “sterile myocardial abscess“ (1,9). The interior of a CMAC is composed of a liquefied mixture of calcium, cholesterol, and fatty acids, which explains the central echolucency on trans- thoracic echocardiography/transesophageal echocar- diography and the central hypodensity in CT imaging (6); it is therefore also known as a “toothpaste-like” tumor among surgeons because of its similar consis- tency. Imagers should be familiar with this rare entity because these lesions have various clinical implica- tions and may even simulate tumors. Due to the increasing use of CT and CMR imaging, CMAC may be more frequently encountered today in clinical prac- tice. Thus, the purpose of our case series was to describe the versatile spectrum of imaging charac- teristics of CMACs, emphasizing the value of multi- modal imaging. CASE 1: DYNAMIC EVOLUTION AND ATYPICAL LOCATION OF A CMAC A 76-year-old man with history of a biological aortic LA ¼ left atrium; LV ¼ left ventricle; RA ¼ right atrium; valve replacement and bypass surgery 11 years earlier RV ¼ right ventricle. was presented for evaluation before valve-in-valve transcatheter aortic valve intervention (TAVI). Car- diac CT imaging revealed a heavily calcified posterior after contrast agent administration (7). CMR provides mitral annulus with a large, atypically located iso- the best tissue characterization and may exclude other lated caseous calcification in its continuation to the entities. CMR usually visualizes a solid mass with aortic outflow tract at the aorto-mitral continuity. low-signal intensity in both T1- and T2-weighted This represents an exceptionally rare CMAC location. sequences, reflecting its calcium content. First-pass Moreover, exophytic lesions at the aortic outflow perfusion sequence reveals no contrast enhancement, tract may lead to complications during positioning 106 Mayr et al. JACC: CASE REPORTS, VOL. 3, NO. 1, 2021 Caseous Mitral Annulus Calcifications JANUARY 2021:104–8 F I G U R E 2 Atypical Mobile Caseous Mitral Annular Calcification Mimicking a Valvular Mass (A) Apical 4-chamber view of transesophageal echocardiography. (B) Apical 4-chamber tissue Doppler in transesophageal echocardiography. (C) Apical 4-chamber view of transthoracic 3D echocardiography. (D) Biphasic iodine contrast-enhanced electrocardiographically gated computed tomography (CT). (E) Basal short-axis slice of late gadolinium enhancement cardiac magnetic resonance imaging. AV ¼ aortic valve; other abbreviations as in Figure 1. and expansion of the prosthesis as well as to reveal the anterior part of this CMAC lesion to be post-procedural device deformation. These lesions reduced to small residues (Figure 1, year 2020), are associated with an increased risk of aortic root whereas the posterior annulus shows an increased rupture during the TAVI procedure (3). calcified mass with small areas of central liquefaction. Furthermore, by evaluating former CT images, we This case contributes to the accumulating evidence were able to reconstruct the dynamic nature of a regarding the dynamic progression from MAC to degenerative CMAC over a period of 19 years: initially, CMAC as well as its remission from CMAC to MAC. As the anterior and posterior mitral annulus showed this case shows, even a temporally and morphologi- minimal calcifications (Figure 1, year 2001) that slowly cally diverse progress of individual parts of the lesion but gradually progressed to a lumpy appearance. seems to be possible. However, 10 years later, a small caseous part devel- Because this disease is associated with complica- oped at the anterior annulus calcification (Figure 1, tions after transcatheter mitral and aortic valve in- year 2011). Three years later, at TAVI-planning CT im- terventions and mitral valve surgery, its clinical aging, as discussed earlier, another increase of the implications are of high importance (10–14). lesion at the anterior mitral annulus was visualized, together with a continued significant decrease in its CASE 2: ATYPICAL MOBILE CMAC MIMICKING density (Figure 1, year 2014). However, the calcified A VALVULAR MASS—DIFFERENTIAL part at the posterior annulus remained stable. Another DIAGNOSIS 2 years later, after the TAVI procedure, the anterior CMAC consisted of a complete liquefaction necrosis Transthoracic and subsequent transesophageal surrounded by a delicate, partially calcified rim echocardiography of a 78-year-old woman with hy- (Figure 1, year 2016). Current CT images from 2020 pertension and a medical history of cerebral emboli JACC: CASE REPORTS, VOL. 3, NO. 1, 2021 Mayr et al. 107 JANUARY 2021:104–8 Caseous Mitral Annulus Calcifications F I G U R E 3 Caseous Mitral Annular Calcification at Cardiac Magnetic Resonance Imaging (A) Basal short-axis slice of a T2-weighted turbo-spin-echo cardiac magnetic resonance imaging sequence. (B) Basal short-axis slice of a T1- weighted turbo-spin-echo cardiac magnetic resonance imaging sequence. (C) 4-chamber view of a cine steady-state free precession cardiac magnetic resonance imaging sequence. (D) 4-chamber view of a late gadolinium enhancement cardiac magnetic resonance imaging sequence. (E) Iodine contrast-enhanced electrocardiographically gated computed tomography (CT). (F) Contrast-free electrocardiographically gated CT. Abbreviations as in Figures 1 and 2. and non–ST-segment elevation myocardial infarction or papillary fibroelastoma could be firmly excluded; revealed a shelf-like, partially echo-dense mass this allowed us to diagnose degenerative CMAC with a beneath the P2 segment of the mitral leaflet but not small central liquefaction component. clearly distinguishable from the posterior mitral valve This case highlights the advantage of a multimodal leaflet (Figures 2A to 2C, Video 1). Due to its mobility imaging approach to clearly differentiate CMAC from (Videos 1 and 2), its heteroechogenicity, and its other lesions. location at the mitral leaflet, the possible differential diagnosis included: 1) valvular mass tumor such as CASE 3: CMAC AT CMR IMAGING papillary fibroelastoma; 2) old, organized vegetation or thrombus; or 3) atypical, mobile CMAC. The incidental finding during adenosine stress CMR A biphasic iodine contrast-enhanced electrocar- of a 45-year-old man with a history of hemodialysis diographically gated CT scan revealed a subtotal treatment and chronic myocardial infarction was a calcified mass located at the junction of the atrio- large, mass-like lesion of mitral annulus adjacent to ventricular groove and posterior mitral leaflet the P1 and P2 segment of the posterior leaflet. Due to (Figure 2D). Because the lesion did not exhibit its CMR signal characteristics (i.e., general T2 hypo- contrast enhancement in both CT and CMR late gad- intense signal [Figure 3A], a weak heterogeneous T1 olinium imaging (Figure 2E), tumors such as myxoma hypointensity [Figure 3B], central hypointensity at 108 Mayr et al. JACC: CASE REPORTS, VOL. 3, NO. 1, 2021 Caseous Mitral Annulus Calcifications JANUARY 2021:104–8 cine steady-state free precession sequence with a CONCLUSIONS brighter border [Figure 3C] evidencing a broad rim of late gadolinium enhancement [Figure 3D]), CMACs exhibit heterogeneous imaging characteris- the differential diagnosis was an atypically located tics, mainly depending on their stage of evolution. fibroma (usually characterized by homogenous Differentiation of other intracardiac masses is there- late enhancement) or a CMAC with a prominent fore challenging. However, using a multimodal im- fibrous capsule. A subsequent electrocardiographi- aging approach, precise diagnosis can be cally gated CT scan revealed a centrally hypodense accomplished. Imagers should be attentive to this mass with irregular calcified borders (Figure 3E) in disease due to its various clinical implications, continuity to a roughly calcified chronic myocardial including those of rapidly evolving transcatheter scar (Figure 3F) at the territory of the circumflex valve procedures. artery. This allowed a safe diagnosis of a CMAC with a liquefied necrotic core surrounded by a AUTHOR DISCLOSURES prominent capsule with an inner fibrotic layer and an outer calcified layer. Imagers, however, may be The authors have reported that they have no relationships relevant to the contents of this paper to disclose. more familiar with the appearances of CMAC at CT scans, which are usually used to plan transcatheter valve interventions and to clarify echocardio- ADDRESS FOR CORRESPONDENCE: Dr. Agnes Mayr, graphically unclear valve masses. This case famil- University Clinic of Radiology, Medical University of iarizes imagers and clinicians with the typical Innsbruck, Anichstrasse 35, A-6020 Innsbruck, imaging features of a CMAC in CMR. Austria. E-mail: [email protected]. REFERENCES 1. Deluca G, Correale M, Ieva R, Del Salvatore B, mitral annulus: a neglected, unrecognized diag- conduction disorders and necessity of pacing after Gramenzi S, Di Biase M. The incidence and clinical nosis. J Am Soc Echocardiogr 2001;14:825–31. transcatheter aortic valve implantation. Pacing course of caseous calcification of the mitral Clin Electrophysiol 2014;37:1520–9. 7. Vanovermeire OM, Duerinckx AJ, Duncan DA, annulus: a prospective echocardiographic study. Russell WG. Caseous calcification of the mitral 12. Durst R, Avelar E, McCarty D, et al. Outcome J Am Soc Echocardiogr 2008;21:828–33. annulus imaged with 64-slice multidetector CT and improvement predictors of mitral regurgita- 2. Pomerance A. Pathological and clinical study of and magnetic resonance imaging. Int J Cardiovasc tion after transcatheter aortic valve implantation. calcification of the mitral valve ring. J Clin Pathol Imaging 2006;22:553–9. J Heart Valve Dis 2011;20:272–81. 1970;23:354–61. 8. Monti L, Renifilo E, Profili M, Balzarini L. Car- 13. Fusini L, Ghulam Ali S, Tamborini G, et al. 3. Motwani M, Fairbairn TA, Jogiya R, diovascular magnetic resonance features of Prevalence of calcification of the mitral valve Greenwood JP, Plein S. Caseous calcification of the caseous calcification of the mitral annulus. annulus in patients undergoing surgical repair of mitral valve complicated by embolization, mitral J Cardiovasc Magn Reson 2008;10:25. mitral valve prolapse. Am J Cardiol 2014;113: regurgitation, and pericardial constriction. Eur 1867–73. 9. McKernan NP, Culp WC Jr., Knight WL, Heart J Cardiovasc Imaging 2012;13:792. Johnston WE, Sniecinski RM, Lazar HL. CASE 14. Okada Y. Surgical management of mitral 4. Asselbergs FW, Mozaffarian D, Katz R, et al. 2—2012 intraoperative diagnosis and manage- annular calcification. Gen Thorac Cardiovasc Surg Association of renal function with cardiac calcifi- ment of caseous calcification of the mitral 2013;61:619–25. cations in older adults: the Cardiovascular Health annulus. J Cardiothorac Vasc Anesth 2012;26: Study. Nephrol Dial Transplant 2009;24:834–40. 327–32. 5. Koito H, Nakamura C, Suzuki J, Takahashi H, 10. Barbanti M, Yang TH, Rodes Cabau J, et al. KEY WORDS cardiac magnetic resonance Iwasaka T. Reduced size of liquefaction necrosis of Anatomical and procedural features associated imaging, caseous mitral annular calcification, mitral annular calcification in chronic renal failure with aortic root rupture during balloon- computed tomography, liquefaction necrosis by using low calcium concentration hemodialysis. expandable transcatheter aortic valve replace- Jpn Circ J 1999;63:490–2. ment. Circulation 2013;128:244–53. 6. Harpaz D, Auerbach I, Vered Z, Motro M, 11. Boerlage-Van Dijk K, Kooiman KM, Yong ZY, AP PE NDIX For supplemental videos, Tobar A, Rosenblatt S. Caseous calcification of the et al. Predictors and permanency of cardiac please see the online version of this paper.