CORRESPONDENCE: RESEARCH CORRESPONDENCE
Intravascular ultrasound assessment of angiographic filling defects in native coronary arteries: Do they always contain thrombi?
Jun-ichi Kotani, MD,
Gary S. Mintz, MD, FACC,
Prithviraj B. Rai, MD,
Chrysoula K. Pappas, MD,
Natalie Gevorkian, MD,
Anh B. Bui, MD,
Augusto D. Pichard, MD, FACC,
Lowell F. Satler, MD, FACC,
William O. Suddath, MD, FACC,
Ron Waksman, MD, FACC,
John R. Laird, Jr, MD, FACC,
Kenneth M. Kent, MD, PhD, FACC and
Neil J. Weissman, MD, FACC
Cardiovascular Research Institute, Washington Hospital Center, 110 Irving Street NW, Washington, DC 20010-2976
(Email: Neil.J.Weissman{at}medstar.net).
To the Editor: Angiographic "thrombi" are diagnosed as either filling defects surrounded by radiographic contrast material or persistent contrast staining. One previous report suggested that some angiographic filling defects are calcified "masses" when imaged using intravascular ultrasound (IVUS) (1). However, the catheter-based approaches to thrombotic versus calcific stenosis may be different. The purpose of this study is to report IVUS findings in patients with angiographic filling-defect lesions.
From 1994 to 1998, 4,083 native artery lesions were angiographically assessed. Excluding 400 in-stent restenosis lesions and 731 with obvious calcium, 6.8% had filling defects. Seventy-eight lesions were assessed using IVUS before the intervention. Seven patients had an acute myocardial infarction (MI) <48 h before IVUS imaging; 36 patients had unstable angina; 22 patients were <6 weeks after MI without recurrent angina; and 13 patients had stable angina or were asymptomatic with a positive stress test. Standard risk factors were tabulated. Written consent was obtained.
Angiographic inclusion required: 1) a filling defect surrounded by contrast material or persistent contrast staining; 2) hazy appearance; and 3) absence of calcium. Quantitative analysis (CAAS II, Pie Medical, The Netherlands) was performed using standard protocols (2). The Thrombolysis In Myocardial Infarction (TIMI) flow grade was visually estimated, and the corrected TIMI frame count was measured as previously reported (3,4).
Intravascular ultrasound was performed after intracoronary administration of 100 to 200 µg nitroglycerin, using a commercially available system (Boston Scientific Corp./SciMed, Maple Grove, Minnesota) and automatic transducer pullback (0.5 mm/s). Qualitative and quantitative analyses was performed according to the criteria of the American College of Cardiology (ACC) Clinical Expert Consensus Document on IVUS (5) using planimetry software (TapeMeasure, INDEC Systems Inc., Capitola, California). A thrombus was a mobile, pedunculated, hypoechoic mass; a brightly speckled mass; or channels or flow within the plaque. Layered appearance (e.g., brightly speckled mass onto the hypoechoic plaque) was considered as mural thrombus. Calcified plaque was defined as >180° (two quadrants). Complex lesion morphologies included ruptured plaque (cavity that communicated with the lumen with an overlying residual fibrous cap fragment) and dissection (longitudinal tear in the plaque parallel to the vessel wall).
Statistical analysis was performed using StatView 5.0 (SAS Institute, Cary, North Carolina). Categorical variables are presented as frequencies and compared using chi-square statistics or the Fisher exact test. Continuous variables are presented as the mean value ± standard deviation and compared using the unpaired Student t test.
Forty-eight angiographic filling defects (61.5%) had IVUS evidence of thrombus, and 30 did not (38.5%). Evidence of thrombus by IVUS was seen in 6 of 10 filling defects with angiographic mobile elements, 18 of 23 filling defects with a proximal and/or distal rounded angiographic appearance, and 7 of 10 filling defects with angiographic "staining." Of the 48 IVUS thrombus-containing lesions, 9 (18.8%) showed thrombus superimposed on calcified plaque.
Thirty angiographic filling defects did not show IVUS evidence of thrombus. Thirteen (43.3%) were calcified plaques, although these lesions were not angiographically calcified (Fig. 1).
View larger version (75K):
[in this window]
[in a new window]
|
Figure 1 Angiogram showing a proximal right coronary artery filling defect with the corresponding intravascular ultrasound images (1 to 3) containing severe calcium.
|
|
Thrombotic versus non-thrombotic lesions by IVUS are compared in Table 1. Thrombotic lesions were more often in males and in patients with unstable clinical presentations, TIMI flow grade 0/1, and prolonged TIMI frame counts. The lesion plaque and media cross-sectional area (p = 0.0585), plaque burden (p = 0.0073), and remodeling index (p = 0.0407) were larger in thrombus-containing lesions. Intraplaque calcium was observed in 27 thrombotic lesions (56%) and in 24 non-thrombotic lesions (80%, p = 0.032). Reference measurements were similar (data not shown).
The ACC/American Heart Association Task Force on Cardiovascular Procedures (6) stratified the risk of percutaneous coronary intervention according to the lesion morphology. "Thrombus-containing" lesions were included in the type B group—lesions with moderate risk. However, other studies have shown that angiographic "thrombus" is an important independent predictor of an adverse outcome after percutaneous coronary intervention (7–9). As previously reported and confirmed in the current analysis, angiographic "thrombi" or filling defects may, in reality, be intraluminal calcified masses (1). This discrepancy can be explained, in part, by the limitation of angiographic assessment of calcium (10,11). Ambrose and Israel (12) reported an angiographic classification of unstable plaques to include complex lesions associated with thrombi. However, thrombi are present in only one-half of ruptured plaques (13). Structurally complex morphologies can retain contrast, resulting in angiographic features of thrombi. Thus, in individual patients, calcified or other non-thrombotic masses may be indistinguishable from thrombi.
Assessment of thrombus by angiography must be considered presumptive. This study was retrospective and did not include in-stent lesions, angiographically calcified lesions, or unstable patient populations.
Angiographic filling defects are not always thrombi; some are nonthrombotic (i.e., plaque, including calcified plaque).
 |
References
|
|---|
- Duissaillant GR, Mintz GS, Pichard AD, et al. Intravascular ultrasound identification of calcified intraluminal lesions misdiagnosed as thrombi by coronary angiography Am Heart J 1996;132:687-689.[CrossRef][Medline]
- Gronenschild E, Janssen J, Tijdens F. CASS II: a second generation system for off-line and on-line quantitative coronary angiography Cathet Cardiovasc Diagn 1994;33:61-75.[Medline]
- The TIMI Study Group The Thrombolysis In Myocardial Infarction (TIMI) trial N Engl J Med 1985;31:932-936.
- Gibson CM, Cannon C, Daley W, et al. TIMI frame count: a quantitative method of assessing coronary artery flow Circulation 1996;93:879-888.[Abstract/Free Full Text]
- Mintz GS, Nissen SE, Anderson WD, et al. American College of Cardiology Clinical Expert Consensus Document on Standards for Acquisition, Measurement and Reporting of Intravascular Ultrasound Studies (IVUS): a report of the American College of Cardiology Task Force on Clinical Expert Consensus Documents J Am Coll Cardiol 2001;37:1478-1492.[Free Full Text]
- Ryan TJ, Bauman WB, Kennedy W, et al. Guidelines for percutaneous transluminal coronary angioplasty: a report of the American Heart Association/American College of Cardiology Task Force on Assessment of Diagnostic and Therapeutic Cardiovascular Procedures J Am Coll Cardiol 1988;12:529-545.[Medline]
- Reeder GS, Bryant SC, Suman VJ, et al. Intracoronary thrombus: still a risk factor for PTCA failure? Cathet Cardiovasc Diagn 1995;34:191-195.[Medline]
- Ellis S, Roubin G, King III S, et al. Angiographic and clinical predictors of acute closure after native vessel coronary angioplasty Circulation 1988;77:372-379.[Abstract/Free Full Text]
- Detre K, Holmes Jr. D, Holubkov R, et al. Incidence and consequences of periprocedural occlusion Circulation 1990;82:739-750.[Abstract/Free Full Text]
- Mintz GS, Popma JJ, Pichard AD, et al. Patterns of calcification in coronary artery disease: a statistical analysis of intravascular ultrasound and coronary angiography in 1,155 lesions Circulation 1995;91:1959-1965.[Abstract/Free Full Text]
- Tuzcu EM, Berktan B, De Franco AC, et al. The dilemma of diagnosing coronary calcification: angiography versus intravascular ultrasound J Am Coll Cardiol 1996;27:832-838.[Abstract]
- Ambrose JA, Israel DH. Angiography in unstable angina Am J Cardiol 1991;68:78B-84B.[CrossRef][Medline]
- Maehara A, Mintz GS, Bui AB, et al. Morphologic and angiographic features of coronary plaque rupture detected by intravascular ultrasound J Am Coll Cardiol 2002;40:904-910.[Abstract/Free Full Text]
This article has been cited by other articles:
|
|
|
|
 
S. H. Rezkalla and D. R. Holmes Jr
Lipid-rich plaque masquerading as a coronary thrombus.
Clin. Med. Res.,
June 1, 2006;
4(2):
119 - 122.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
Top
References