A case with a large intracoronary mobile mass diagnosed with a calcified thrombus using optical frequency domain imaging and intravascular ultrasound.

OBJECTIVES: A calcified thrombus is rare, but needs to be recognized and to be differentiated from calcified nodule.
METHODS: We report a case of acute coronary syndrome and a large intracoronary mobile mass, which was identified as a calcified thrombus by optical frequency domain imaging and intravascular ultrasound.
RESULTS: Successful direct stenting indicated that mobile mass was a calcified thrombus, not a calcified nodule.
CONCLUSIONS: Cardiologists should be aware that an intracoronary mobile mass could be a calcified thrombus. This diagnosis can be confirmed through the combined use of optical frequency domain imaging and intravascular ultrasound.

Case description

An 82-year-old woman presented with chest pain at rest and cold sweats lasting 10 min. Her electrocardiogram showed no ischemic ST changes because she did not have symptoms when she arrived at the hospital. Based on her laboratory data revealing elevated Troponin T (0.102 ng/mL), she was diagnosed with acute coronary syndrome. Then, we applied a 6-F sheath via a right trans-radial approach. Coronary angiography with a 6-F Judkins Right 4.0, Goodtec® (Goodman, Gifu, Japan) revealed a mobile mass with a stalk in the right coronary artery (RCA; Figure 1(a), arrow, and Online Video 1) and moderate stenosis in the left anterior descending artery (LAD) (Figure 1(b), arrow, and Online Video 2). We suspected the mobile mass to be a thrombus, which was the culprit lesion, and decided to perform percutaneous coronary intervention (PCI). We exchanged to 7-F sheath in order to apply a large size Rotablator® (Boston Scientific, Boston, MA, USA) in case of a calcified nodule. First, we engaged Judkins Right 4.0 Profit® (Goodman) and inserted a guide wire, Sionblue® (Asahi Intecc, Nagoya, Japan) and performed intravascular ultrasound (IVUS), ViewIt® (Terumo, Tokyo, Japan). However, it showed a hyperechoic signal with acoustic shadowing suspected to be superficial microcalcifications (Figure 1(c), arrow, and Online Video 3). Then, we performed optical frequency domain imaging (OFDI), FastView® (Terumo, Tokyo, Japan) which revealed a high-luminance protruding mass with attenuation that was suspected to be a calcified thrombus (Figure 1(d), arrow, and Online Video 4). We confirmed the RCA as the culprit and proceeded with direct stent insertion (Promus Premier®, 4 mm × 24 mm, Boston Scientific). The final angiography and IVUS revealed acceptable results (Figure 1(e) and (f) and Online Videos 5 and 6). Then, we performed staged PCI for LAD because we could not conclusively determine the culprit artery. After both PCIs, she remained asymptomatic for 18 months.

Figure 1.

(a) Diagnostic coronary angiogram of the RCA showing a mobile plaque (an arrow), (b) diagnostic coronary angiogram of the LAD showing stenosis in the LAD (an arrow), (c) IVUS image showing a hyperechoic signal with acoustic shadowing (an arrow), (d) OCT image showing a high-luminance protruding mass with attenuation (an arrow), and (e) and (f) final coronary angiogram and IVUS image showing acceptable results.

Discussion

The IVUS image of the mobile mass demonstrated a hyperechoic signal and acoustic shadowing, revealing superficial microcalcifications above the sequence of mild plaque. These results could be caused by a red calcified thrombus or a calcified nodule.[1] Although virtual histology-IVUS imaging may color an intracoronary thrombus,[2] we did not perform this procedure because it might not visualize areas lying behind microcalcifications due to acoustic shadowing. Because OFDI can detect a thrombus clearly,[3] we performed OFDI, which revealed a mass with attenuation, behind the calcification, which was suspected to be a red thrombus. There were no erosions noted from plaque rupture, but a red thrombus could have caused acute coronary syndrome.[4-6] An OFDI image of a calcified thrombus has been previously shown to present as a protruding mass with OFDI-signal backscattering and attenuation.[7] Furthermore, if it was an intracoronary embolus, this mobile mass could be embolized more distally or moved distally with injection of contrast. Moreover, there was no evidence of paroxysmal atrial fibrillation, which is a major cause of intracoronary embolization.[8] Thus, we concluded that this mobile mass was a calcified thrombus and performed direct stenting successfully. Successful direct stenting indicated that mobile mass was a calcified thrombus, not a calcified nodule. Although there was a concern of distal embolization, we did not perform thrombus aspiration or distal protection because there was no data favoring the use of these devices and because the use of such procedures could cause stroke due to thrombus migration.[9,10] Cardiologists should be aware that an intracoronary mobile mass could be a calcified thrombus. This diagnosis can be confirmed through the combined use of OFDI and IVUS.