To the Editor:

We appreciate Kealhofer and colleagues' report on their beneficial use of cardiac computed tomography (CT) for evaluating prosthetic aortic valve dysfunction.1  We want to contribute further by drawing attention to the role of cardiac CT in differentiating periprosthetic masses in patients who have prosthetic heart valves (PHVs).

Transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), cinefluoroscopy, and cardiac CT are noninvasive imaging methods for evaluating suspected PHV dysfunction.2  Because acoustic shadowing and low resolution caused by prosthetic material usually preclude differentiating obstructive masses and their causes by TTE, abnormalities thus detected should be investigated further by using TEE or cardiac CT. Real-time 3-dimensional TEE provides better views of the atrial and ventricular sides of mitral prostheses, clarifies relationships between cardiac structures, and helps to discriminate pannus from thrombus.3  However, this method is less adequate for evaluating aortic PHVs because of the distance between the esophagus and aortic valve. In such cases, cardiac CT complements TEE, and indeed it has emerged as a diagnostic tool in evaluating mechanical PHVs.4  Attenuation values of abnormal masses adjacent to the PHVs may provide quantitative data for differentiating pannus from thrombus.5  Because of histopathologic differences, the radiographic attenuation of pannus may be markedly higher than that of thrombus.

We have reported a quantitative approach to distinguish pannus from thrombus with use of cardiac CT. With high sensitivity and specificity, periprosthetic masses with attenuation values ≥145 Hounsfield units (HU) were associated with the presence of pannus formation, and lower values, with thrombus formation. Furthermore, masses with values <90 HU were almost always completely lysable by means of thrombolytic therapy.5  Kealhofer and colleagues1  successfully delineated subclinical aortic bioprosthetic valve thrombosis with the complementary use of cardiac CT and prescribed the patient anticoagulation for 3 months. Quantitative analysis with cardiac CT may similarly differentiate PHV thrombosis from pannus, which resists anticoagulation or thrombolytic therapy.6 

Despite the limitations of streak artifacts and volume averaging, cardiac CT has incremental value in identifying and characterizing periprosthetic masses, and it can guide the treatment of patients who have PHV dysfunction.

References

References
1.
Kealhofer
JV,
Markowitz
JS,
Nijjar
PS.
Use of computed tomography to distinguish thrombus from pannus on a bioprosthetic aortic valve
.
Tex Heart Inst J
2019
;
46
(
3
):
219
21
.
2.
Gunduz
S,
Kalcik
M,
Gursoy
MO,
Guner
A,
Ozkan
M.
Diagnosis, treatment & management of prosthetic valve thrombosis: the key considerations
.
Expert Rev Med Devices
2020
;
17
(
3
):
209
21
.
3.
Gursoy
MO,
Kalcik
M,
Yesin
M,
Karakoyun
S,
Bayam
E,
Gunduz
S,
Ozkan
M.
A global perspective on mechanical prosthetic heart valve thrombosis: diagnostic and therapeutic challenges
.
Anatol J Cardiol
2016
;
16
(
12
):
980
9
.
4.
Nam
K,
Suh
YJ,
Han
K,
Park
SJ,
Kim
YJ,
Choi
BW.
Value of computed tomography radiomic features for differentiation of periprosthetic mass in patients with suspected prosthetic valve obstruction
.
Circ Cardiovasc Imaging
2019
;
12
(
11
):
e009496
.
5.
Ueda
T,
Teshima
H,
Fukunaga
S,
Aoyagi
S,
Tanaka
H.
Evaluation of prosthetic valve obstruction on electrocardiographically gated multidetector-row computed tomography--identification of subprosthetic pannus in the aortic position
.
Circ J
2013
;
77
(
2
):
418
23
.
6.
Gunduz
S,
Ozkan
M,
Kalcik
M,
Gursoy
OM,
Astarcioglu
MA,
Karakoyun
S,
et al.
Sixty-four-section cardiac computed tomography in mechanical prosthetic heart valve dysfunction: thrombus or pannus
.
Circ Cardiovasc Imaging
2015
;
8
(
12
):
e003246
.

Letters to the Editor should be no longer than 2 double-spaced typewritten pages and should generally contain no more than 6 references. They should be signed, with the expectation that the letters will be published if appropriate. The right to edit all correspondence in accordance with Journal style is reserved by the editors.