CASE REPORTS
Acute Left Ventricular Remodeling After Myocardial Infarction on Transthoracic Echocardiography: A Case Series Deepak Koul, MD, Renee Bess, RDCS, RVT, FASE, Arshad Rehan, MD, and Gerald Cohen, MD, FACC, FASE, Detroit, Michigan
The authors describe left ventricular myocardial changes on transthoracic echocardiography in patients imaged within 72 hours of acute infarction. Endocardial separation from the mid myocardium, echocardiographic contrast penetration into the myocardium, and regional contrast swirling were observed. This case series also illustrates how contrast imaging may enhance recognition of early postinfarction remodeling. (J Am Soc Echocardiogr 2009;22:1309.e1-1309.e5.) Keywords: Left ventricular remodeling, Trabeculation, Bands, Acute myocardial infarction, Contrast imaging
Acute myocardial infarction (AMI) results in left ventricular (LV) remodeling, which manifests as disproportionate thinning and dilation of the myocardium. Postinfarction remodeling has been arbitrarily divided into an early phase (within 72 hours) and a late phase (beyond 72 hours). The early phase involves expansion of the infarct zone, which may result in early ventricular rupture or aneurysm formation. Late remodeling involves the left ventricle globally and is associated with time-dependent dilatation, cavity shape distortion, and hypertrophy of the noninfarcted segments.1 In a review of a case series of patients with myocardial infarctions in our lab, we noted different patterns of early-phase remodeling during transthoracic imaging. This report illustrates these patterns and the utility of contrast imaging in this clinical setting.
CASES The following cases illustrate acute changes in the myocardium, with and without contrast, during transthoracic echocardiography. The fifth case also included serial examination, with resting normal LV function 2 years prior to infarction. Images were acquired using a GE Vivid 7 (GE Healthcare, Milwaukee, WI), except in the last case, in which Philips 5500 and IE-33 machines (Philips Medical Systems, Andover, MA) were also used. Contrast imaging was performed using Definity (Lantheus Medical Imaging, North Billerica, MA) and was optimized with the mitral-level focal zone, a mechanical index of 0.24 to 0.28, a harmonic frequency of 1.5 to 1.7, moderate range compression, and a frame fate of 25 to 35 frames/s. No patient had an adverse reaction to the contrast.
Case 1 A 44-year-old man with hypertension, diabetes, and human immunodeficiency virus infection on antiretroviral therapy presented with an acute ST-elevation myocardial infarction secondary to acute thrombotic occlusion of the proximal and mid segments of the left anterior descending coronary artery. Successful primary stent placement was performed. Two-dimensional echocardiography performed after 24 hours showed moderate LV dysfunction, with apical dyskinesis and mid to distal anterolateral akinesis. Precontrast images also showed areas of echolucency beneath the endocardium (arrows) (Figures 1A and 1B). With echocardiographic contrast, the myocardium showed pockets of uneven wall thickness and contrast enhancement (asterisk) with areas of thinning (arrow) and lucency (arrowhead) (Figures 1C and 1D), resulting in a ‘‘spongy’’ appearance. Video 1 also shows spontaneous contrast in the precontrast image and swirling of echocardiographic contrast toward the apex. Case 2 A 52-year-old male smoker with hypertension and diabetes developed acute chest pain and ST elevation. Precontrast images 36 hours after symptom onset showed moderate LV dysfunction affecting the apex and distal segments and spontaneous contrast in the LV cavity (Video 2). Contrast images showed variable thinning of the apex and penetration of contrast in pockets (arrow) into the myocardium (Figure 2B). In addition, dense swirling of contrast was localized to the apex despite optimization of machine settings and contrast administration (arrow) (Figure 2C). Apical long-axis images showed mid to distal anteroseptal and apical akinesis despite suboptimal endocardial definition (Figure 2D). Enhanced images showed a linear penetration of contrast from the LV cavity into the apical myocardium (arrows) (Figures 2E and 2F). Also see Video 2.
From the Division of Cardiology, St John Hospital and Medical Center, Detroit, Michigan. Reprint requests: Deepak Koul, MD, St John Hospital and Medical Center, Cardiac Catheterization Lab, 22101 Moross Road, 2nd Floor VEP, Detroit, MI 48236 (E-mail:
[email protected]). 0894-7317/$36.00 Copyright 2009 by the American Society of Echocardiography. doi:10.1016/j.echo.2009.05.016
Case 3 A 47-year-old woman with hypertension, diabetes, and chronic kidney disease presented with chest pain and was diagnosed with nonST-elevation myocardial infarction. Transthoracic echocardiography showed moderate LV dysfunction, with akinesis of the mid to distal septum and apex (Video 3). These segments also showed lucency 1309.e1
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Figure 1 Precontrast apical four chamber images (A and magnified on B) showing areas of echolucency beneath the endocardium (arrows). With contrast (C and D), pockets of uneven wall thickness and contrast enhancement (asterisk) with areas of thinning (arrow) and lucency (arrowhead) are seen. Figure 3 Echolucency is seen beneath mid to distal septal endocardium (arrow) on the unenhanced apical four chamber and parasternal long axis views (A and C). Contrast imaging (B and D) shows separation of the mid to distal septal endocardium from the underlying myocardium in a band like fashion (black arrows) and penetration of contrast into the apical myocardium (white arrow). resembled a band (black arrows) that extended from the mid septum to the apex. Contrast also appeared to penetrate the apical myocardium (white arrow) (Figures 3B and 3D). Case 4
Figure 2 Unenhanced apical four chamber and apical long axis images show suboptimal endocardial definition (A and D). Contrast image (B) show variable apical thinning and penetration of contrast in pockets (arrow) into the myocardium. C shows dense swirling of contrast (arrow). Enhanced images (E and magnified F) show a linear penetration of contrast from LV cavity into apical myocardium (arrows).
beneath the mid to distal septal subendocardium (arrow) (Figures 3A and 3C). Contrast imaging revealed separation of the mid to distal septal endocardium from the underlying myocardium. This finding
A 53-year-old man with hypertension and cocaine abuse was brought to the emergency room after a sudden cardiac arrest. Electrocardiography showed STelevation in the anterior chest leads. Coronary angiography revealed total occlusion of the mid left anterior descending coronary artery, which was stented. Precontrast images showed severe LV dysfunction with distal septal and apical akinesis and bandlike separation of the endocardium from the underlying infarcted mid myocardium (arrows) (Figures 4A and 4B). A lucent space between these layers (asterisk) on the precontrast images was better delineated with contrast (Figures 4C and 4D), which also showed swirling (Video 4), trabeculation, and uneven thinning of the apical wall. The lifted endocardium (black arrows) showed breaks in its contour. Case 5 A 57-year-old female smoker with hypertension presented with typical chest pain and new-onset left bundle branch block. Two years earlier, she had undergone dobutamine echocardiography, with normal results and normal baseline function (Figures 5A and D). Her acute
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Figure 4 Precontrast apical four chamber images (A and B) show band like separation of the endocardium from the underlying infarcted mid myocardium (arrows). A lucent space (asterisk) is better delineated with contrast (C and D) which also show trabeculation, uneven thinning of the apical wall and breaks in the contour of the lifted endocardium (black arrows).
infarction was due to total occlusion of the proximal left anterior descending coronary artery, which was treated with stent placement during primary percutaneous coronary intervention. Transthoracic echocardiography 20 hours after symptom onset showed moderate LV dysfunction and akinesis to dyskinesis of the mid to distal septum, inferior wall, and apex (Figures 5B and 5E). Bandlike separation of the endocardium from the underlying infarcted mid myocardium (arrow) was noted that was distinct from the papillary muscles (asterisk). Lucency was present beneath the lifted subendocardial layer and within the apical myocardium and was enhanced by contrast imaging in the 2-chamber view (Figure 5C) (though not well visualized in the 4-chamber view in Figure 5F). See Video 5.
DISCUSSION Acute ischemia leading to infarction is associated with a rapid sequence of pathologic changes that result in the necrosis and dissolution of myocardial tissue, with subsequent segmental remodeling and expansion. LV remodeling on echocardiography after infarction has generally been described in terms of chronic changes as a process that occurs over a period of weeks to months. However, acute changes in the myocardial wall include changes in wall structure as well as segmental dysfunction. Our cases illustrate the morphology of these structural changes, including uneven wall thickness, lifting of the endomyocardium, and trabeculation that was evident during both systole and diastole. We also noted that these structural changes
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were associated with more severe segmental wall motion abnormalities and local contrast swirling. Our findings indicate that infarction and subsequent remodeling are another possible cause of trabeculations and bands. Tamborini et al2 described similar findings as ‘‘anomalous images,’’ with a prevalence of 46.7% in a large series of patients who underwent transthoracic echocardiography. These anomalies were associated with LV systolic dysfunction, which is consistent with our observation of systolic dysfunction and bandlike separation of the endocardium from the infarcted subendocardium. The assessment of parameters of LV remodeling after AMI has therapeutic and prognostic implications in that advanced LV remodeling is associated with worse outcomes.3,4 In a study from the Mayo Clinic, ‘‘regional diastolic endocardial contour abnormalities’’ observed with contrast-enhanced stress echocardiography were associated with higher coronary artery disease risk. However, these changes were primarily attributed to myocardial ischemia, not necrosis, which is postulated as the cause of the findings in our series.5 Failure of the myocardium to enhance after administration of echocardiographic contrast has also been associated with adverse remodeling by distinguishing scar from viable tissue. These findings were noted in studies during 1-month and 3-month follow-up periods.6,7 Our results indicate that penetration of contrast into the wall after AMI may cause some confusion in making this distinction. In a recent report, reperfusion intramyocardial hemorrhage was observed with magnetic resonance imaging.8 Our studies were similarly conducted after reperfusion for AMI. Although pathologic correlation is needed, intramyocardial and subendocardial lucency, enhanced with contrast, is consistent with the same phenomenon. Contrast may be helpful in delineating the endocardium and showing the uneven wall thickness as pockets of the myocardium have dissolved. Currently, contrast agents are often used for the assessment of LV thrombi and masses, LV noncompaction or apical hypertrophy, and right ventricular dysplasia and thrombus, and in stress echocardiography for regional wall motion assessment.9-11 One case report has shown the benefit of using contrast echocardiography for the diagnosis of subacute myocardial rupture after AMI.12 Although echocardiographic studies have examined thrombus formation in AMI, acute and subacute structural changes in the infarcting endocardium have not been described with contrast echocardiography.13,14 In our case series, contrast enhanced the visualization of acute and subacute remodeling of the infracted LV. Areas of myocardial lucency as observed on precontrast images are opacified with contrast. In addition, contrast may delineate uneven wall thinning more clearly. Contrast appeared to penetrate into some segments of dysfunctional myocardium and also helped in the recognition of endocardial lifting and in the detection of stasis. Recently published data support the safety of contrast imaging in the setting of AMI.15 All our patients presented with AMIs (non-ST-elevation myocardial infarction, ST-elevation myocardial infarction, and new-onset left bundle branch block) involving the left anterior descending coronary artery. Additional study is needed to determine whether this phenomenon occurs with posterior circulation occlusion or is associated with specific electrocardiographic patterns. Verification of our findings is warranted with description of longitudinal data in a larger series of patients involving diverse imaging modalities and pathologic correlation.
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Figure 5 A and D show normal LV function on baseline apical two chamber and four chamber images. Bandlike separation of the endocardium from the underlying infarcted mid myocardium (arrows), distinct from the papillary muscles (asterisk), is noted on both precontrast and contrast images (B, E; and C, F). REFERENCES 1. Sutton MG, Sharpe N. Left ventricular remodeling after myocardial infarction: pathophysiology and therapy. Circulation 2000;27:2981-8. 2. Tamborini G, Pepi M, Celeste F, Muratori M, Susini F, Maltagliati A, et al. Incidence and characteristics of left ventricular false tendons and trabeculations in the normal and pathologic heart by second harmonic echocardiography. J Am Soc Echocardiogr 2004;17:367-74. 3. Khumri TM, Nayyar S, Idupulapati M, Magalski A, Stoner CN, Kusnetzky LL, et al. Usefulness of myocardial contrast echocardiography in predicting late mortality in patients with anterior wall acute myocardial infarction. Am J Cardiol 2006;98:1150-5. 4. Lim TK, Burden L, Janardhanan R, Dwivedi G, Ping C, Moon J, Pennell DJ, et al. Contrast echocardiography versus gated single photon emission computed tomography for the assessment of parameters of left ventricular remodeling after acute myocardial infarction. J Am Soc Echocardiogr 2006;19:280-4. 5. Cukon-Buttignoni S, Abdelmoneim SS, Ehrsam JE, Barnes ME, Hagen ME, Carlson LA, et al. Regional diastolic contour abnormalities during contrast
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stress echocardiography: improved detection of coronary artery disease. J Am Soc Echocardiogr 2008;21:1109-15. Lepper W, Kamp O, Vanoverschelde JL, Franke A, Sieswerda GT, Pasquet A, et al. Intravenous myocardial contrast echocardiography predicts left ventricular remodeling in patients with acute myocardial infarction. J Am Soc Echocardiogr 2002;15:849-56. Bi X, Deng Y, Shentu W, Xiong L, Zhang Y, Yu F, et al. Evaluation of the left ventricular remodeling in patients with myocardial infarction after revascularization with intravenous real-time myocardial contrast echocardiography. J Huazhong Univ Sci Technolog Med Sci 2008;28:287-90. O’Regan DP, Ahmed R, Karunanithy N, Neuwirth C, Tan Y, Durighel G, et al. Reperfusion hemorrhage following acute myocardial infarction: assessment with T2* mapping and effect on measuring the area at risk. Radiology 2009;250:916-22. Olszewski R, Timperley J, Cezary S, Monaghan M, Nihoyannopoulis P, Senior R, et al. The clinical applications of contrast echocardiography. Eur J Echocardiogr 2007;8:S13-23. Bhatia VK, Senior R. Contrast echocardiography: evidence for clinical use. J Am Soc Echocardiogr 2008;21:417-8.
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11. Lowery MH, Martel JA, Zambrano JP, Ferreira A, Eco L, Gallagher A. Noncompaction of the ventricular myocardium: the use of contrast-enhanced echocardiography in diagnosis. J Am Soc Echocardiogr 2003;16:94-6. 12. Garcı´a-Ferna´ndez MA, Macchioli RO, Moreno PM, Yangu¨ela MM, Thomas JB, Sendo´n JL, et al. Use of contrast echocardiography in the diagnosis of subacute myocardial rupture after myocardial infarction. J Am Soc Echocardiogr 2001;14:945-7. 13. Rehan A, Kanwar M, Rosman H, Ahmed S, Ali A, Gardin J, et al. Incidence of post myocardial infarction left ventricular thrombus formation in the era
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of primary percutaneous intervention and glycoprotein IIb/IIIa inhibitors. A prospective observational study. Cardiovasc Ultrasound 2006;4:20. 14. Mansencal N, Nasr IA, Pillie`re R, Farcot JC, Joseph T, Lacombe P, et al. Usefulness of contrast echocardiography for assessment of left ventricular thrombus after acute myocardial infarction. Am J Cardiol 2007;15: 1667-70. 15. Nucifora G, Marsan NA, Siebelink HM, van Werkhoven JM, Schuijf JD, Schalij MJ, et al. Safety of contrast-enhanced echocardiography within 24 h after acute myocardial infarction. Eur J Echocardiogr 2008;9:816-8.
