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Thrombus age, clinical presentation, and reperfusion grade in myocardial infarction
Cardiovascular Pathology 23 (2014) 126–130
Contents lists available at ScienceDirect
Cardiovascular Pathology
Original Article
Thrombus age, clinical presentation, and reperfusion grade in myocardial infarction Antoni Carol a,⁎, Mariana Bernet b, Antoni Curós a, Oriol Rodríguez-Leor a, Jordi Serra a, Eduard Fernández-Nofrerías a, Josepa Mauri a, Antoni Bayes-Genís a a b
Cardiology Service, Hospital Universitari Germans Trias i Pujol, Badalona Pathology Service, Hospital General de Granollers
a r t i c l e
i n f o
Article history: Received 8 October 2013 Received in revised form 23 December 2013 Accepted 15 January 2014 Keywords: Thrombus Embolization Myocardial infarction Coronary angioplasty Reperfusion Pathology
a b s t r a c t Introduction: Autopsy studies show that dynamic coronary thrombosis leads to infarction. We studied intracoronary thrombus age in ST-segment elevation myocardial infarction (STEMI) and its relationship with clinical presentation and epicardial reperfusion grade. Methods and results: Intracoronary thrombectomy was performed in 131 STEMI patients within 24 h after symptom onset, and material sufficient for pathological analysis was retrieved from 81 patients. Thrombus age was classified as fresh (b1 day), lytic (1 to 5 days), or organized (N5 days). A fresh thrombus was found in 48 patients (60%), whereas the thrombus showed lytic or organized changes in 33 patients (40%). Both thrombus and plaque material were aspirated in 40% of cases. Lytic or organized thrombi were aspirated in one third of the cases early (b12 h) after symptom onset, and fresh thrombi were also aspirated in one third of STEMI of N 12 h evolution. In multivariable analysis, fresh thrombus was associated with both persistent ST-segment elevation (even after 12 h of onset) during percutaneous coronary intervention [odds ratio (OR) 4.23, 95% confidence interval (CI) 1.05–17.42, P = .042) and a previous history of ischemic heart disease (OR 4.54, 95% CI 1.41–14.64, P = .011). There were no associations between thrombus composition and epicardial reperfusion grade or the presence of the no-reflow phenomenon. Plaque components were found in all cases of distal embolization (5%). Conclusion: Intracoronary thrombi aspirated in STEMI frequently show more than one stage of maturation. Fresh thrombi predominate in patients with known ischemic heart disease or persistent ST-segment elevation. Summary: In STEMI, thromboaspiration revealed thrombi at different stages of maturation, supporting a dynamic process of rupture and repair of the atherosclerotic plaque. Fresh thrombi were present more frequently within 12 h of infarction onset but also in patients with symptoms beyond 12 h. When containing plaque material, thrombi were often associated with macroscopic distal embolization during angioplasty. © 2014 Elsevier Inc. All rights reserved.
1. Introduction Exposure of a previously ruptured or eroded atherosclerotic plaque to the vessel lumen can lead to the formation of thrombi and development of ST-segment elevation myocardial infarction (STEMI). If duration of coronary occlusion is extended beyond 20 min, myocardial necrosis begins to occur [1]. Primary percutaneous coronary intervention (PCI) is the therapy of choice in the first 12 h of evolution, although patients can also benefit beyond 12 h if chest pain persists or there is evidence of ongoing ischemia or signs of heart failure [1]. The procedure may be complicated by the no-reflow phenomenon or distal embolization [2,10,12]. Further, data show that intracoronary thrombus composition in terms of age may be an independent predictor of outcome during PCI [3]. The use of thrombectomy systems that facilitate Conflicts of interest: none. ⁎ Corresponding author at: Cardiology Service, Hospital Universitari Germans Trias i Pujol, Crta. de Can Ruti, Camí de les escoles, s/n, 08916 Badalona, Barcelona, Spain. Tel.: +34 93 4978662; fax: +34 93 4978654. E-mail address: [email protected] (A. Carol). 1054-8807/$ – see front matter © 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.carpath.2014.01.007
suction of the intracoronary thrombi before implanting a stent during primary PCI allows the pathological analysis of the material retrieved by aspiration in vivo [5,9]. The objective of this study was to prospectively analyze the pathological composition of intracoronary thrombi obtained from patients with STEMI treated with PCI within the first 24 h of symptom onset and to analyze the relationship between thrombus age, clinical presentation, and epicardial reperfusion grade. 2. Methods 2.1. Study population Between May 2006 and September 2007, we treated 186 consecutive patients with PCI within the first 24 h after the onset of STEMI. Patients with chest pain and symptoms for ≤ 12 h were eligible for primary PCI if the admission 12-lead electrocardiogram (ECG) showed ≥ 1 mm ST-segment elevation in ≥ 2 contiguous inferior or lateral leads or ≥ 2 mm in ≥ 2 contiguous precordial leads. Rescue
A. Carol et al. / Cardiovascular Pathology 23 (2014) 126–130
angioplasty was performed in patients treated with fibrinolysis without clinical and/or ECG criteria of reperfusion at 90 min [1]. In patients with STEMI presenting 12–24 h after symptom onset, PCI was performed if chest pain was still present upon admission, or if ECG showed persistent ST-segment elevation or Killip–Kimball classification ≥ II [1] upon admission. The study complies with the Declaration of Helsinki and was approved by the hospital’s ethics committee, and informed consent was obtained from participants. 2.2. Coronary intervention and thrombus aspiration Prior to initiation of PCI, all patients received a loading dose of 500 mg aspirin, 600 mg of clopidogrel orally, and 5000 IU of heparin. Thrombolysis in Myocardial Infarction (TIMI) flow grades were classified using previously established criteria [1]. The procedure was considered a success if the final TIMI flow grade was 3 and residual stenosis was b 20%. Glycoprotein IIb–IIIa blockers were used at the discretion of the operator. Thrombectomy was performed in cases with angiographically visible thrombus burden in which the coronary artery was suitable for passage of the catheter and was considered successful when a TIMI grade flow ≥ 2 was achieved after using the device. Aspirated blood and intracoronary material were collected and filtered to retrieve the thrombotic material (Fig. 1A). Distal embolism was defined as distal migration of the thrombus or as macroscopic distal occlusion of the treated vessel or one of its branches after completing the procedure. No-reflow was defined as a TIMI flow grade b 2 that was not attributed to dissection or epicardial coronary vasospasm plus no evidence of macroscopic distal embolism upon angiography. STsegment recovery, an indicator of coronary reperfusion, was considered if there was a ≥ 50% reduction post-PCI [1,9]. Ischemic heart disease was defined as history of previous myocardial infarction or angina or history of previous coronary artery bypass grafting or PCI. 2.3. Thrombus analysis and pathological classification The aspirated intracoronary material was fixed immediately in 10% formalin and was considered appropriate for pathological analysis if
127
it had a minimum size of 2 mm. After it was embedded in paraffin, the retrieved material was cut into 4-μm serial sections and stained with hematoxylin and eosin (HE). Thrombi were classified by pathology into three groups according to the accepted definitions of thrombus age [4]: (a) fresh thrombus (b1 day), comprised of platelet aggregates, erythrocytes, intact granulocytes, and fibrin (Fig. 1B); (b) lytic thrombus (1 to 5 days), characterized by areas of colliquative necrosis and granulocytes with karyorrhexis (Fig. 1C); and (c) organized thrombus (N5 days), characterized by the presence of smooth muscle cells, homogeneous or hyaline fibrin, and depositions of connective tissue and capillary vessel ingrowth (Figs. 1D and 2A). For the purpose of the current analysis, lytic and organized thrombi were combined into one group and compared against the fresh thrombus group. We also analyzed the degree of thrombi heterogeneity identifying components of another type of thrombus, i.e., fresh thrombus components in a predominantly organized thrombus or vice versa. To better identify smooth muscle cells and neovascularization within thrombi, additional immunohistochemistry was performed on specimens that contained lytic/organized thrombi. Primary monoclonal antibodies included anti-smooth muscle α-actin (1A4, Dako, Denmark), which labels smooth muscle cells (Fig. 2B), and anti-CD34 (QBEnd10, Dako), which labels endothelial cells (Fig. 2C). Plaque components were identified based on the presence of inflammatory cells, cholesterol crystals, collagen tissue, and/or calcification (Fig. 3A–D).
2.4. Statistical analysis Continuous variables were expressed as means and standard deviations, and categorical variables were expressed as absolute frequency. The Student’s t test was used to compare means, and the χ 2 test, or Fisher’s Exact Test, if necessary, was used to evaluate the relationship between dichotomous variables. Multivariable logistic regression analysis was performed using the backward stepwise method to estimate odds ratios (ORs) for the variables associated with fresh thrombus (all variables with a P value b .1 in the univariate analysis were incorporated into the model). SPSS 15 software (SPSS,
Fig. 1. (A) Macroscopic appearance of the aspirated thrombus after thrombectomy. (B) Microphotograph of a fresh thrombus (HE staining, ×400). *Nonhomogeneous fibrin, **leukocytes, †platelet aggregates. (C) Microphotograph of a lytic thrombus (HE staining, ×400). *Colliquative necrosis, †granulocytes with karyorrhexis. (D) Microphotograph of an organized thrombus (HE staining, ×400). *Endothelial cells, **erythrocytes, †hyaline and homogenized fibrin.
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Fig. 2. (A) Microphotograph of an organized thrombus (HE staining, ×600). *Endothelial cells, †smooth muscle cells. (B) Organized thrombus stained with anti-smooth muscle α-actin (×400). Arrows indicate smooth muscle cells. (C) Organized thrombus stained with anti-CD34 (×400). Arrows indicate endothelial cells.
Inc., Chicago, IL, USA) was used to perform the statistical analysis. A P value b .05 was considered statistically significant. 3. Results Thrombectomy was used in 131 of 186 consecutive patients treated with PCI and was effective in extracting intracoronary thrombus in 118 (90%); the middle age of these patients was 61 ± 13 years, 87% were men, and there were 31% patients with history of ischemic heart disease. In these 118 patients, PCI was performed within the first 12 h following onset of STEMI in 86% of the patients (Fig. 4); a final TIMI grade of 3 was
achieved in 84% of cases, although 11 (9%) patients experienced noreflow phenomenon and 9 (8%) had macroscopic distal embolization. There were no differences in successful thrombectomy between fibrynolisis-treated patients compared with untreated patients. Six patients died during hospitalization due to cardiogenic shock. 3.1. Thrombus age and relationship with clinical presentation and PCI outcome The material retrieved was sufficient for pathological analysis in 81 cases. A fresh thrombus was found in 48 (60%) patients, whereas a lytic
Fig. 3. Microphotographs with plaque components (HE staining ×400). (A) Microphotograph with totality of macrophages. (B) **Cholesterol crystals, arrows indicate giant multinucleate cells, †calcification. (C) *Erythrocytes, **inflammatory cells, †calcification. (D) *Macrophages, †cholesterol crystals.
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Table 1 Univariable analysis according to thrombus composition
14% 31%
< 3 hours 3-6 hours
19%
6-12 hours > 12 hours 36%
PCI: percutaneous coronary intervention Fig. 4. Time elapsed from onset of symptoms to PCI in the 118 patients in whom thrombectomy was effective.
or organized thrombus was aspirated in 33 (40%). In 40% of the cases, plaque components were also identified: soft plaque constituents in 24 (74%), microcalcifications in 4 (13%), and soft plaque constituents plus calcium in 4 (13%). There were more lytic/organized thrombi with fresh thrombus components than inversely (94% vs. 48%, P = .001). Fresh thrombi were retrieved most often during the first 12 h after symptom onset (90% of all fresh thrombi), mainly in patients with persistent chest pain and ST-segment elevation and in patients with a history of ischemic heart disease or those with prior PCI. Fig. 5 shows thrombus composition according to the STEMI evolution time frame. The epicardial reperfusion grade achieved after PCI and the appearance of no-reflow phenomenon did not differ for patients with fresh thrombi aspirated versus patients in whom lytic or organized thrombi were retrieved. Plaque components were detected more frequently in the four patients with distal embolization compared with the other patients (100% vs. 38%, P = .02), three of whom showed soft plaque constituents. In the 67 patients in whom it was possible to analyze the post-PCI ECG, there were no differences in the grade of ST-segment recovery (≥50%) according to the type of thrombus (63% fresh vs. 67% lytic/organized, P = .79). In the multivariable analysis, which included history of ischemic heart disease, previous PCI, STEMI evolution ≤ 12 h, presence of chest pain during PCI, and ST-segment elevation during PCI, the variables that remained significantly associated with fresh thrombus were the presence of ST-segment elevation during the procedure [OR 4.23, 95%
Fresh thrombus Lytic or organized thrombus
70 60
66
64
63
64
%
50 40 30
34
37
36
36
20 10 0 <3h
3-6 h
6-12 h
> 12 h
Hours of STEMI evolution Fig. 5. Type of aspirated thrombus according to the time frame of STEMI evolution.
Variable
Fresh thrombus Lytic/organized P value (n = 48) thrombus (n = 33)
Ischemic heart disease Previous PCI Treatment with ASA and/or clopidogrel Angina 24 h prior to AMI Evolution ≤ 12 h Chest pain during PCI ST-segment elevation during PCI Primary PCI Rescue PCI Killip I class upon admission VT and/or VF Use of abciximab Multivessel disease Postthrombectomy TIMI grade ≥ 2 Final TIMI flow grade 3 No-reflow Distal embolization
20 (42%) 12 (25%) 20 (42%)
5 (15%) 2 (6%) 11 (33%)
.01 .02 .49
22 (46%) 43 (90%) 43 (90%) 46 (96%) 37 (77%) 8 (13%) 40 (83%) 9 (11%) 41 (85%) 9 (11%) 41 (85%)
14 (42%) 24 (72%) 23 (69%) 27 (81%) 21 (64%) 4 (12%) 27 (81%) 4 (12%) 26 (79%) 7 (21%) 25 (77%)
.54 .04 .02 .04 .21 1.00 .95 .99 .55 .78 .38
39 (81%) 7 (14%) 2 (4%)
29 (88%) 2 (6%) 2 (6%)
.11 .29 .51
The categorical variables are reported as n (%). AMI, acute myocardial infarction; ASA, aspirin; PCI, percutaneous coronary intervention; VF, ventricular fibrillation; VT, ventricular tachycardia.
confidence interval (CI) 1.055–17.42, P = .042) and history of ischemic heart disease (OR 4.54, 95% CI 1.407–14.64, P = .011) (Table 1). 4. Discussion 4.1. Thrombus age and clinical presentation A main finding of this study was the pathological identification of thrombi of different ages in the setting of STEMI during the first 24 h after onset of symptoms. These results support the hypothesis of dynamic coronary thrombosis in which there are both plaque rupture and healing occurring in acute coronary syndrome, with the thrombus undergoing formation and resolution and progressively accumulating in the arterial lumen; thus, the thrombus can evolve subclinically over days or weeks until it completely blocks an epicardial coronary artery [6,7]. This theory may explain why, in our study, old thrombi components were identified in 48% of cases with a fresh thrombus. The presence of a fresh thrombus was predominant in the first 12 h after symptom onset, yet in one third of these patients, the retrieved intracoronary material showed characteristics of an older thrombus. This is in agreement with the report by Rittersma et al., who used the same strict criteria of thrombus age as in our study and found older thrombi in 51% of 211 with STEMI of b 6 h evolution, suggesting that the absence of complete healing of an aging thrombus may play a role in the occurrence of sudden occlusive coronary thrombosis [4]. Although our analysis showed lytic or organized thrombi in two thirds of patients treated with PCI in the time interval after 12 h, fresh thrombi were also found, more often in patients with persistent chest pain or ST-segment elevation during PCI. Moreover, 94% of lytic/ organized thrombi had associated some grade of fresh thrombus components, indicating the presence of recent thrombotic activity. All these findings may explain why 81% of patients with lytic/organized thrombi has ST-segment elevation when performing PCI and why the differences between the two groups, still being present, are not too large. These pathological findings are consistent with current recommendations for the practice of primary angioplasty and rescue angioplasty for the management of STEMI [1] since both variables indicate thrombotic activity and identify patients that may benefit from reperfusion therapy beyond 12 h after symptom onset. Fresh thrombi were aspirated more frequently from the arteries of patients with a history of ischemic heart disease and from those with prior PCI. Presence of ischemic preconditioning may facilitate a more
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rapid myocardial reperfusion in the setting of STEMI [8]; this mechanism could influence the histopathology of the thrombi obtained in patients with history of ischemic heart disease who suffered transient ischemic episodes previously. Other possible explanation is the influence of chronic antiplatelet therapy in thrombus age, inhibiting or delaying thrombus formation, but there were no differences in this variable between the two groups of thrombus retrieved. 4.2. Thrombus age and epicardial reperfusion grade Despite the higher frequency of older thrombus in patients with more hours of STEMI evolution in this study, we did not find a relationship between the final reperfusion grade after PCI and the composition of the aspirated thrombus, as in other studies. The elevated use of coronary stent implantation (98%) and glycoprotein IIb/IIIa inhibitors (80%) may have influenced these results. We found no relationship either between thrombus age and ST-segment recovery post-PCI, as in other study [9]. These results may have been influenced by the time to practice the ECG: in the study of Verouden et al., [9] the postprocedural ECG was recorded at the time of last contrast injection, while in our study, ECG was recorded when patient was already out of the catheterization laboratory, shortly after ending the procedure but not immediately after. Regarding complications, plaque components were found in the aspirated intracoronary material in the four patients with macroscopic distal embolization, as in some other reports [10–12]. There is growing evidence of the substantial impact of embolization of multiple particles on the final grade of myocardial reperfusion and on the onset of complications such as no-reflow after angioplasty [2,10–12]. In patients with STEMI, these phenomena have been correlated with the presence of atheromatous plaque, whether detected by intravascular ultrasound [11] or after obtaining plaque fragments following thrombus aspiration [10–12]. 4.3. Study limitations This was a single-center analysis with a limited sample size, although the sample size was comparable to that of samples in similar pathological studies. The manner in which thrombi were collected may influence the composition of the analyzed material: while some studies use a thrombectomy device that involves suction of intracoronary thrombus, as in our study, others use a distal protection porous device placed beyond the target lesion. Finally, only patients in whom enough thrombotic material for a comprehensive pathological
analysis was aspirated were included in the analysis, and the clinical course of these patients may not necessarily be extrapolated to the global population of patients treated with PCI in the acute phase of STEMI.
Acknowledgments We thank Anna Bettancourt Alonso and Patricia Medina Ibáñez for pathology technical support.
References [1] Steg P, James SK, Atar D, Badano LP, Blomstrom Lundqvist C, Borger MA, et al. ESC guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation. Eur Heart J 2012;33:2569–619. [2] Fokkema ML, Vlaar PJ, Svilaas T, Vogelzang M, Amo D, Diercks G, Suurmeijer A, Zijlstra F. Incidence and clinical consequence of distal embolization on the coronary angiogram after percutaneous coronary intervention for ST-elevation myocardial infarction. Eur Heart J 2009;30:908–15. [3] Kramer M, van der Wal AC, Koch KT, Ploegmakers J, van der Schaaf R, Henriques J, et al. Presence of older thrombus is an indepenent predictor of long-term mortality in patients with ST-elevation myocardial infarction treated with thrombus aspiration during primary percutaneous coronary intervention. Circulation 2008;118:1810–6. [4] Rittersma S, van der Wal AC, Koch KT, Piek JJ, Henriques J, Mulder KJ, et al. Plaque instability frequently occurs days or weeks before occlusive coronary thrombosis. Circulation 2005;111:1160–5. [5] Silvain J, Collet J-P, Nagaswami C, Beygui F, Edmonson KE, Bellemain-Appaix A, et al. Composite of coronary thrombus in acute myocardial infarction. J Am Coll Cardiol 2011;57:1359–67. [6] Burke AP, Kolodgie FD, Farb A, Weber DK, Malcom GT, Smialek J, Virmani R. Healed plaque ruptures and sudden coronary death: evidence that subclinical rupture has a role in plaque progression. Circulation 2001;103:934–40. [7] Ojio S, Takatsu H, Tanaka T, Ueno K, Yokoya K, Matsubara T, et al. Considerable time from the onset of plaque rupture and/or thrombi until the onset of acute myocardial infarction in humans: coronary angiographic findings within 1 week before the onset of infarction. Circulation 2000;102:2063–9. [8] Andreotti F, Pasceri V, Hacket D, Davies G, Haider A, Maseri A. Preinfarction angina as a predictor of more rapid coronary thrombolysis in patients with acute myocardial infarction. N Engl J Med 1996;334:7–12. [9] Verouden N, Kramer M, Li X, Meuwissen M, Koch K, Henriques J, et al. Histopathology of aspirated thrombus and its association with ST-segment recovery in patients undergoing primary percutaneous coronary intervention with routine thrombus aspiration. Catheter Cardiovasc Interv 2011;77(1):35–42. [10] Limbruno U, De Carlo M, Pistolesi S, Micheli A, Petronio AS, Camacci T, et al. Distal embolization during primary angioplasty: histopathologic features and predictability. Am Heart J 2005;150:102–8. [11] Tanaka A, Kawarabayashi T, Nishibori Y, Sano T, Nishida Y, Fukuda D, et al. Noreflow phenomenon and lesion morphology in patients with acute myocardial infarction. Circulation 2002;105:2148–52. [12] Kotani J, Nanto S, Mintz GS, Kitakaze M, Ohara T, Morozumi T, et al. Plaque gruel of atheromatous coronary lesion may contribute to the no-reflow phenomenon in patients with acute coronary syndrome. Circulation 2002;106:1672–7.
Contents lists available at ScienceDirect
Cardiovascular Pathology
Original Article
Thrombus age, clinical presentation, and reperfusion grade in myocardial infarction Antoni Carol a,⁎, Mariana Bernet b, Antoni Curós a, Oriol Rodríguez-Leor a, Jordi Serra a, Eduard Fernández-Nofrerías a, Josepa Mauri a, Antoni Bayes-Genís a a b
Cardiology Service, Hospital Universitari Germans Trias i Pujol, Badalona Pathology Service, Hospital General de Granollers
a r t i c l e
i n f o
Article history: Received 8 October 2013 Received in revised form 23 December 2013 Accepted 15 January 2014 Keywords: Thrombus Embolization Myocardial infarction Coronary angioplasty Reperfusion Pathology
a b s t r a c t Introduction: Autopsy studies show that dynamic coronary thrombosis leads to infarction. We studied intracoronary thrombus age in ST-segment elevation myocardial infarction (STEMI) and its relationship with clinical presentation and epicardial reperfusion grade. Methods and results: Intracoronary thrombectomy was performed in 131 STEMI patients within 24 h after symptom onset, and material sufficient for pathological analysis was retrieved from 81 patients. Thrombus age was classified as fresh (b1 day), lytic (1 to 5 days), or organized (N5 days). A fresh thrombus was found in 48 patients (60%), whereas the thrombus showed lytic or organized changes in 33 patients (40%). Both thrombus and plaque material were aspirated in 40% of cases. Lytic or organized thrombi were aspirated in one third of the cases early (b12 h) after symptom onset, and fresh thrombi were also aspirated in one third of STEMI of N 12 h evolution. In multivariable analysis, fresh thrombus was associated with both persistent ST-segment elevation (even after 12 h of onset) during percutaneous coronary intervention [odds ratio (OR) 4.23, 95% confidence interval (CI) 1.05–17.42, P = .042) and a previous history of ischemic heart disease (OR 4.54, 95% CI 1.41–14.64, P = .011). There were no associations between thrombus composition and epicardial reperfusion grade or the presence of the no-reflow phenomenon. Plaque components were found in all cases of distal embolization (5%). Conclusion: Intracoronary thrombi aspirated in STEMI frequently show more than one stage of maturation. Fresh thrombi predominate in patients with known ischemic heart disease or persistent ST-segment elevation. Summary: In STEMI, thromboaspiration revealed thrombi at different stages of maturation, supporting a dynamic process of rupture and repair of the atherosclerotic plaque. Fresh thrombi were present more frequently within 12 h of infarction onset but also in patients with symptoms beyond 12 h. When containing plaque material, thrombi were often associated with macroscopic distal embolization during angioplasty. © 2014 Elsevier Inc. All rights reserved.
1. Introduction Exposure of a previously ruptured or eroded atherosclerotic plaque to the vessel lumen can lead to the formation of thrombi and development of ST-segment elevation myocardial infarction (STEMI). If duration of coronary occlusion is extended beyond 20 min, myocardial necrosis begins to occur [1]. Primary percutaneous coronary intervention (PCI) is the therapy of choice in the first 12 h of evolution, although patients can also benefit beyond 12 h if chest pain persists or there is evidence of ongoing ischemia or signs of heart failure [1]. The procedure may be complicated by the no-reflow phenomenon or distal embolization [2,10,12]. Further, data show that intracoronary thrombus composition in terms of age may be an independent predictor of outcome during PCI [3]. The use of thrombectomy systems that facilitate Conflicts of interest: none. ⁎ Corresponding author at: Cardiology Service, Hospital Universitari Germans Trias i Pujol, Crta. de Can Ruti, Camí de les escoles, s/n, 08916 Badalona, Barcelona, Spain. Tel.: +34 93 4978662; fax: +34 93 4978654. E-mail address: [email protected] (A. Carol). 1054-8807/$ – see front matter © 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.carpath.2014.01.007
suction of the intracoronary thrombi before implanting a stent during primary PCI allows the pathological analysis of the material retrieved by aspiration in vivo [5,9]. The objective of this study was to prospectively analyze the pathological composition of intracoronary thrombi obtained from patients with STEMI treated with PCI within the first 24 h of symptom onset and to analyze the relationship between thrombus age, clinical presentation, and epicardial reperfusion grade. 2. Methods 2.1. Study population Between May 2006 and September 2007, we treated 186 consecutive patients with PCI within the first 24 h after the onset of STEMI. Patients with chest pain and symptoms for ≤ 12 h were eligible for primary PCI if the admission 12-lead electrocardiogram (ECG) showed ≥ 1 mm ST-segment elevation in ≥ 2 contiguous inferior or lateral leads or ≥ 2 mm in ≥ 2 contiguous precordial leads. Rescue
A. Carol et al. / Cardiovascular Pathology 23 (2014) 126–130
angioplasty was performed in patients treated with fibrinolysis without clinical and/or ECG criteria of reperfusion at 90 min [1]. In patients with STEMI presenting 12–24 h after symptom onset, PCI was performed if chest pain was still present upon admission, or if ECG showed persistent ST-segment elevation or Killip–Kimball classification ≥ II [1] upon admission. The study complies with the Declaration of Helsinki and was approved by the hospital’s ethics committee, and informed consent was obtained from participants. 2.2. Coronary intervention and thrombus aspiration Prior to initiation of PCI, all patients received a loading dose of 500 mg aspirin, 600 mg of clopidogrel orally, and 5000 IU of heparin. Thrombolysis in Myocardial Infarction (TIMI) flow grades were classified using previously established criteria [1]. The procedure was considered a success if the final TIMI flow grade was 3 and residual stenosis was b 20%. Glycoprotein IIb–IIIa blockers were used at the discretion of the operator. Thrombectomy was performed in cases with angiographically visible thrombus burden in which the coronary artery was suitable for passage of the catheter and was considered successful when a TIMI grade flow ≥ 2 was achieved after using the device. Aspirated blood and intracoronary material were collected and filtered to retrieve the thrombotic material (Fig. 1A). Distal embolism was defined as distal migration of the thrombus or as macroscopic distal occlusion of the treated vessel or one of its branches after completing the procedure. No-reflow was defined as a TIMI flow grade b 2 that was not attributed to dissection or epicardial coronary vasospasm plus no evidence of macroscopic distal embolism upon angiography. STsegment recovery, an indicator of coronary reperfusion, was considered if there was a ≥ 50% reduction post-PCI [1,9]. Ischemic heart disease was defined as history of previous myocardial infarction or angina or history of previous coronary artery bypass grafting or PCI. 2.3. Thrombus analysis and pathological classification The aspirated intracoronary material was fixed immediately in 10% formalin and was considered appropriate for pathological analysis if
127
it had a minimum size of 2 mm. After it was embedded in paraffin, the retrieved material was cut into 4-μm serial sections and stained with hematoxylin and eosin (HE). Thrombi were classified by pathology into three groups according to the accepted definitions of thrombus age [4]: (a) fresh thrombus (b1 day), comprised of platelet aggregates, erythrocytes, intact granulocytes, and fibrin (Fig. 1B); (b) lytic thrombus (1 to 5 days), characterized by areas of colliquative necrosis and granulocytes with karyorrhexis (Fig. 1C); and (c) organized thrombus (N5 days), characterized by the presence of smooth muscle cells, homogeneous or hyaline fibrin, and depositions of connective tissue and capillary vessel ingrowth (Figs. 1D and 2A). For the purpose of the current analysis, lytic and organized thrombi were combined into one group and compared against the fresh thrombus group. We also analyzed the degree of thrombi heterogeneity identifying components of another type of thrombus, i.e., fresh thrombus components in a predominantly organized thrombus or vice versa. To better identify smooth muscle cells and neovascularization within thrombi, additional immunohistochemistry was performed on specimens that contained lytic/organized thrombi. Primary monoclonal antibodies included anti-smooth muscle α-actin (1A4, Dako, Denmark), which labels smooth muscle cells (Fig. 2B), and anti-CD34 (QBEnd10, Dako), which labels endothelial cells (Fig. 2C). Plaque components were identified based on the presence of inflammatory cells, cholesterol crystals, collagen tissue, and/or calcification (Fig. 3A–D).
2.4. Statistical analysis Continuous variables were expressed as means and standard deviations, and categorical variables were expressed as absolute frequency. The Student’s t test was used to compare means, and the χ 2 test, or Fisher’s Exact Test, if necessary, was used to evaluate the relationship between dichotomous variables. Multivariable logistic regression analysis was performed using the backward stepwise method to estimate odds ratios (ORs) for the variables associated with fresh thrombus (all variables with a P value b .1 in the univariate analysis were incorporated into the model). SPSS 15 software (SPSS,
Fig. 1. (A) Macroscopic appearance of the aspirated thrombus after thrombectomy. (B) Microphotograph of a fresh thrombus (HE staining, ×400). *Nonhomogeneous fibrin, **leukocytes, †platelet aggregates. (C) Microphotograph of a lytic thrombus (HE staining, ×400). *Colliquative necrosis, †granulocytes with karyorrhexis. (D) Microphotograph of an organized thrombus (HE staining, ×400). *Endothelial cells, **erythrocytes, †hyaline and homogenized fibrin.
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Fig. 2. (A) Microphotograph of an organized thrombus (HE staining, ×600). *Endothelial cells, †smooth muscle cells. (B) Organized thrombus stained with anti-smooth muscle α-actin (×400). Arrows indicate smooth muscle cells. (C) Organized thrombus stained with anti-CD34 (×400). Arrows indicate endothelial cells.
Inc., Chicago, IL, USA) was used to perform the statistical analysis. A P value b .05 was considered statistically significant. 3. Results Thrombectomy was used in 131 of 186 consecutive patients treated with PCI and was effective in extracting intracoronary thrombus in 118 (90%); the middle age of these patients was 61 ± 13 years, 87% were men, and there were 31% patients with history of ischemic heart disease. In these 118 patients, PCI was performed within the first 12 h following onset of STEMI in 86% of the patients (Fig. 4); a final TIMI grade of 3 was
achieved in 84% of cases, although 11 (9%) patients experienced noreflow phenomenon and 9 (8%) had macroscopic distal embolization. There were no differences in successful thrombectomy between fibrynolisis-treated patients compared with untreated patients. Six patients died during hospitalization due to cardiogenic shock. 3.1. Thrombus age and relationship with clinical presentation and PCI outcome The material retrieved was sufficient for pathological analysis in 81 cases. A fresh thrombus was found in 48 (60%) patients, whereas a lytic
Fig. 3. Microphotographs with plaque components (HE staining ×400). (A) Microphotograph with totality of macrophages. (B) **Cholesterol crystals, arrows indicate giant multinucleate cells, †calcification. (C) *Erythrocytes, **inflammatory cells, †calcification. (D) *Macrophages, †cholesterol crystals.
A. Carol et al. / Cardiovascular Pathology 23 (2014) 126–130
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Table 1 Univariable analysis according to thrombus composition
14% 31%
< 3 hours 3-6 hours
19%
6-12 hours > 12 hours 36%
PCI: percutaneous coronary intervention Fig. 4. Time elapsed from onset of symptoms to PCI in the 118 patients in whom thrombectomy was effective.
or organized thrombus was aspirated in 33 (40%). In 40% of the cases, plaque components were also identified: soft plaque constituents in 24 (74%), microcalcifications in 4 (13%), and soft plaque constituents plus calcium in 4 (13%). There were more lytic/organized thrombi with fresh thrombus components than inversely (94% vs. 48%, P = .001). Fresh thrombi were retrieved most often during the first 12 h after symptom onset (90% of all fresh thrombi), mainly in patients with persistent chest pain and ST-segment elevation and in patients with a history of ischemic heart disease or those with prior PCI. Fig. 5 shows thrombus composition according to the STEMI evolution time frame. The epicardial reperfusion grade achieved after PCI and the appearance of no-reflow phenomenon did not differ for patients with fresh thrombi aspirated versus patients in whom lytic or organized thrombi were retrieved. Plaque components were detected more frequently in the four patients with distal embolization compared with the other patients (100% vs. 38%, P = .02), three of whom showed soft plaque constituents. In the 67 patients in whom it was possible to analyze the post-PCI ECG, there were no differences in the grade of ST-segment recovery (≥50%) according to the type of thrombus (63% fresh vs. 67% lytic/organized, P = .79). In the multivariable analysis, which included history of ischemic heart disease, previous PCI, STEMI evolution ≤ 12 h, presence of chest pain during PCI, and ST-segment elevation during PCI, the variables that remained significantly associated with fresh thrombus were the presence of ST-segment elevation during the procedure [OR 4.23, 95%
Fresh thrombus Lytic or organized thrombus
70 60
66
64
63
64
%
50 40 30
34
37
36
36
20 10 0 <3h
3-6 h
6-12 h
> 12 h
Hours of STEMI evolution Fig. 5. Type of aspirated thrombus according to the time frame of STEMI evolution.
Variable
Fresh thrombus Lytic/organized P value (n = 48) thrombus (n = 33)
Ischemic heart disease Previous PCI Treatment with ASA and/or clopidogrel Angina 24 h prior to AMI Evolution ≤ 12 h Chest pain during PCI ST-segment elevation during PCI Primary PCI Rescue PCI Killip I class upon admission VT and/or VF Use of abciximab Multivessel disease Postthrombectomy TIMI grade ≥ 2 Final TIMI flow grade 3 No-reflow Distal embolization
20 (42%) 12 (25%) 20 (42%)
5 (15%) 2 (6%) 11 (33%)
.01 .02 .49
22 (46%) 43 (90%) 43 (90%) 46 (96%) 37 (77%) 8 (13%) 40 (83%) 9 (11%) 41 (85%) 9 (11%) 41 (85%)
14 (42%) 24 (72%) 23 (69%) 27 (81%) 21 (64%) 4 (12%) 27 (81%) 4 (12%) 26 (79%) 7 (21%) 25 (77%)
.54 .04 .02 .04 .21 1.00 .95 .99 .55 .78 .38
39 (81%) 7 (14%) 2 (4%)
29 (88%) 2 (6%) 2 (6%)
.11 .29 .51
The categorical variables are reported as n (%). AMI, acute myocardial infarction; ASA, aspirin; PCI, percutaneous coronary intervention; VF, ventricular fibrillation; VT, ventricular tachycardia.
confidence interval (CI) 1.055–17.42, P = .042) and history of ischemic heart disease (OR 4.54, 95% CI 1.407–14.64, P = .011) (Table 1). 4. Discussion 4.1. Thrombus age and clinical presentation A main finding of this study was the pathological identification of thrombi of different ages in the setting of STEMI during the first 24 h after onset of symptoms. These results support the hypothesis of dynamic coronary thrombosis in which there are both plaque rupture and healing occurring in acute coronary syndrome, with the thrombus undergoing formation and resolution and progressively accumulating in the arterial lumen; thus, the thrombus can evolve subclinically over days or weeks until it completely blocks an epicardial coronary artery [6,7]. This theory may explain why, in our study, old thrombi components were identified in 48% of cases with a fresh thrombus. The presence of a fresh thrombus was predominant in the first 12 h after symptom onset, yet in one third of these patients, the retrieved intracoronary material showed characteristics of an older thrombus. This is in agreement with the report by Rittersma et al., who used the same strict criteria of thrombus age as in our study and found older thrombi in 51% of 211 with STEMI of b 6 h evolution, suggesting that the absence of complete healing of an aging thrombus may play a role in the occurrence of sudden occlusive coronary thrombosis [4]. Although our analysis showed lytic or organized thrombi in two thirds of patients treated with PCI in the time interval after 12 h, fresh thrombi were also found, more often in patients with persistent chest pain or ST-segment elevation during PCI. Moreover, 94% of lytic/ organized thrombi had associated some grade of fresh thrombus components, indicating the presence of recent thrombotic activity. All these findings may explain why 81% of patients with lytic/organized thrombi has ST-segment elevation when performing PCI and why the differences between the two groups, still being present, are not too large. These pathological findings are consistent with current recommendations for the practice of primary angioplasty and rescue angioplasty for the management of STEMI [1] since both variables indicate thrombotic activity and identify patients that may benefit from reperfusion therapy beyond 12 h after symptom onset. Fresh thrombi were aspirated more frequently from the arteries of patients with a history of ischemic heart disease and from those with prior PCI. Presence of ischemic preconditioning may facilitate a more
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rapid myocardial reperfusion in the setting of STEMI [8]; this mechanism could influence the histopathology of the thrombi obtained in patients with history of ischemic heart disease who suffered transient ischemic episodes previously. Other possible explanation is the influence of chronic antiplatelet therapy in thrombus age, inhibiting or delaying thrombus formation, but there were no differences in this variable between the two groups of thrombus retrieved. 4.2. Thrombus age and epicardial reperfusion grade Despite the higher frequency of older thrombus in patients with more hours of STEMI evolution in this study, we did not find a relationship between the final reperfusion grade after PCI and the composition of the aspirated thrombus, as in other studies. The elevated use of coronary stent implantation (98%) and glycoprotein IIb/IIIa inhibitors (80%) may have influenced these results. We found no relationship either between thrombus age and ST-segment recovery post-PCI, as in other study [9]. These results may have been influenced by the time to practice the ECG: in the study of Verouden et al., [9] the postprocedural ECG was recorded at the time of last contrast injection, while in our study, ECG was recorded when patient was already out of the catheterization laboratory, shortly after ending the procedure but not immediately after. Regarding complications, plaque components were found in the aspirated intracoronary material in the four patients with macroscopic distal embolization, as in some other reports [10–12]. There is growing evidence of the substantial impact of embolization of multiple particles on the final grade of myocardial reperfusion and on the onset of complications such as no-reflow after angioplasty [2,10–12]. In patients with STEMI, these phenomena have been correlated with the presence of atheromatous plaque, whether detected by intravascular ultrasound [11] or after obtaining plaque fragments following thrombus aspiration [10–12]. 4.3. Study limitations This was a single-center analysis with a limited sample size, although the sample size was comparable to that of samples in similar pathological studies. The manner in which thrombi were collected may influence the composition of the analyzed material: while some studies use a thrombectomy device that involves suction of intracoronary thrombus, as in our study, others use a distal protection porous device placed beyond the target lesion. Finally, only patients in whom enough thrombotic material for a comprehensive pathological
analysis was aspirated were included in the analysis, and the clinical course of these patients may not necessarily be extrapolated to the global population of patients treated with PCI in the acute phase of STEMI.
Acknowledgments We thank Anna Bettancourt Alonso and Patricia Medina Ibáñez for pathology technical support.
References [1] Steg P, James SK, Atar D, Badano LP, Blomstrom Lundqvist C, Borger MA, et al. ESC guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation. Eur Heart J 2012;33:2569–619. [2] Fokkema ML, Vlaar PJ, Svilaas T, Vogelzang M, Amo D, Diercks G, Suurmeijer A, Zijlstra F. Incidence and clinical consequence of distal embolization on the coronary angiogram after percutaneous coronary intervention for ST-elevation myocardial infarction. Eur Heart J 2009;30:908–15. [3] Kramer M, van der Wal AC, Koch KT, Ploegmakers J, van der Schaaf R, Henriques J, et al. Presence of older thrombus is an indepenent predictor of long-term mortality in patients with ST-elevation myocardial infarction treated with thrombus aspiration during primary percutaneous coronary intervention. Circulation 2008;118:1810–6. [4] Rittersma S, van der Wal AC, Koch KT, Piek JJ, Henriques J, Mulder KJ, et al. Plaque instability frequently occurs days or weeks before occlusive coronary thrombosis. Circulation 2005;111:1160–5. [5] Silvain J, Collet J-P, Nagaswami C, Beygui F, Edmonson KE, Bellemain-Appaix A, et al. Composite of coronary thrombus in acute myocardial infarction. J Am Coll Cardiol 2011;57:1359–67. [6] Burke AP, Kolodgie FD, Farb A, Weber DK, Malcom GT, Smialek J, Virmani R. Healed plaque ruptures and sudden coronary death: evidence that subclinical rupture has a role in plaque progression. Circulation 2001;103:934–40. [7] Ojio S, Takatsu H, Tanaka T, Ueno K, Yokoya K, Matsubara T, et al. Considerable time from the onset of plaque rupture and/or thrombi until the onset of acute myocardial infarction in humans: coronary angiographic findings within 1 week before the onset of infarction. Circulation 2000;102:2063–9. [8] Andreotti F, Pasceri V, Hacket D, Davies G, Haider A, Maseri A. Preinfarction angina as a predictor of more rapid coronary thrombolysis in patients with acute myocardial infarction. N Engl J Med 1996;334:7–12. [9] Verouden N, Kramer M, Li X, Meuwissen M, Koch K, Henriques J, et al. Histopathology of aspirated thrombus and its association with ST-segment recovery in patients undergoing primary percutaneous coronary intervention with routine thrombus aspiration. Catheter Cardiovasc Interv 2011;77(1):35–42. [10] Limbruno U, De Carlo M, Pistolesi S, Micheli A, Petronio AS, Camacci T, et al. Distal embolization during primary angioplasty: histopathologic features and predictability. Am Heart J 2005;150:102–8. [11] Tanaka A, Kawarabayashi T, Nishibori Y, Sano T, Nishida Y, Fukuda D, et al. Noreflow phenomenon and lesion morphology in patients with acute myocardial infarction. Circulation 2002;105:2148–52. [12] Kotani J, Nanto S, Mintz GS, Kitakaze M, Ohara T, Morozumi T, et al. Plaque gruel of atheromatous coronary lesion may contribute to the no-reflow phenomenon in patients with acute coronary syndrome. Circulation 2002;106:1672–7.