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High-risk ECG patterns in ACS—Need for guideline revision
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ScienceDirect Journal of Electrocardiology 46 (2013) 535 – 539 www.jecgonline.com
High-risk ECG patterns in ACS—Need for guideline revision Itamar Birnbaum, MD, a Yochai Birnbaum, MD b,⁎ a
The Department of Medicine, Baylor College of Medicine and St Luke Episcopal Hospital, Houston, TX, USA b The Section of Cardiology, Baylor College of Medicine and St Luke Episcopal Hospital. Houston, TX, USA
Abstract
The current guidelines advocate distinct approaches (urgent reperfusion therapy) to patients with suspected acute coronary syndromes (ACS) presenting with ST elevation (STE) versus patients without STE on their electrocardiogram (ECG). This is based on the paradigm that STE represents ongoing transmural ischemia due to an acute occlusion of an epicardial coronary artery whereas the significance of other ECG findings is more contentious. The role of urgent coronary angiography in patients without STE is less clear and initial stabilization with conservative treatment is recommended. However, in some cases the distinction between STEMI and non-STE-ACS is difficult. Acute occlusion of a coronary artery may cause less than the current recommended threshold STE. On the other hand, many patients may have STE secondary to nonischemic etiology. In many patients with non-STE-ACS the coronary artery is not completely occluded at the time of presentation and there are rapid fluctuations in the severity of ischemia and hence, dynamic changes are observed in the ECG. Several ECG patterns associated with particular coronary anatomy and high-risk prognosis have been identified. Patients with ACS presenting with these high-risk patterns should probably be referred for coronary angiography with the possibility of urgent intervention with the goal of prevention of ischemic complications, rather than for immediate myocardial salvage, as in classic STEMI. © 2013 Elsevier Inc. All rights reserved.
Keywords:
ECG; ACS; Guideline revision
Introduction The current guidelines make a clear distinction in the triage and initial management of patients presenting with symptoms suggestive of acute coronary syndrome (ACS) with and without ST elevation (STE) in their presenting ECG. 1,2 STE is thought to manifest ongoing transmural ischemia due to an acute occlusion of a coronary artery. Emergent reperfusion therapy is indicated to “save” myocardium and limit the ischemic damage. Tremendous effort has been invested to shorten the time from initiation of symptoms (or presentation) to reperfusion. The current guidelines suggest that patients presenting without STE can be initially managed conservatively and coronary angiography can be performed later to prevent reinfarction, but not to save myocardium. However, many patients presenting with chest pain may have STE secondary to nonischemic etiologies. 3 Many classic patterns of nonischemic STE can be easily identified (early repolarization, normal pattern, pericarditis, etc). How⁎ Corresponding author. The Section of Cardiology, Baylor College of Medicine, MS: BCM620, One Baylor Plaza, Houston, TX 77030. E-mail address: [email protected] 0022-0736/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jelectrocard.2013.06.008
ever, it should be remembered that the magnitude and distribution of these nonischemic STE patterns may dramatically change over time. For example, the magnitude of STE secondary to early repolarization tends to diminish with tachycardia, whereas STE secondary to aneurysm or left bundle branch block may increase with tachycardia. On the other hand, some patients with an acute occlusion of a coronary artery with ongoing ischemia may have borderline STE or no STE at all. 2 The European guidelines suggest that ongoing suspicion of myocardial ischemia, despite medical therapy, is an indication for emergency coronary angiography, even in patients presenting without STE. 2 In theory, patients presenting with STE have ongoing ischemia and ongoing necrosis that should be stopped by emergency revascularization. On the other hand, patients with ACS without STE may show diverse angiographic and clinical findings that may signify incomplete and dynamic occlusions. In many patients, symptoms diminish by the time of presentation. In these patients, the ECG is not expected to show acute ischemic changes or localize the site of coronary thrombus. In such instances, the ECG may show the “footprints” of previous ischemia—(terminal) T-wave inversions with insignificant ST deviation. However, if an
536
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ECG is recorded during an episode of active symptoms, dynamic changes indicating ischemia can be detected. Thus, it is crucial to interpret the ECG while knowing the clinical data and especially whether or not the patient was symptomatic when the recording was done. Currently, the severity and/or quality of symptoms cannot be stored in the digital database. Future ECG machines should include a method to enter this information, along with the demographic data when the ECG is recorded. Several high-risk ECG patterns have been described in patients with non-STE-ACS. 4 These patterns can be divided into those with ongoing ischemia (that do not result in STE) and those without ongoing ischemia (reperfusion of a culprit lesion with high-risk features) (Table 1):
Patterns with ongoing ischemia Tall positive T waves without significant ST deviation The first sign of acute ischemia is an increase in the amplitude of the T waves. This usually precedes STE. In some patients, STE does not occur and the only manifestation of ischemia is tall, symmetric T waves. It has been suggested that persistent tall T waves without STE is seen in patients with good collateral circulation that “protects” the myocardium. 5 This pattern may be difficult to diagnose on presentation, as there are wide variations in the amplitude of the T waves and factors other than ischemia (heart rate, potassium levels, etc) may interplay. Usually, this pattern is recognized only after subsequent ECG changes are noted upon progression or alleviation of ischemia (development of Q waves, shortening of the R waves and/or T-wave inversion). It is unclear whether emergency coronary angiography
Table 1 ECG patterns associated with high risk. a. Ongoing ischemia 1. Isoelectric ST segment with tall positive T waves. If dynamic changes and not associated with hyperkalemia, consider tight occlusion of an epicardial artery. The role of emergency coronary angiography has not been established. 2. Upsloping ST depression with tall positive T waves. May indicate acute subendocardial ischemia due to tight narrowing of an epicardial artery, especially if seen in a patient without tachycardia. Urgent coronary angiography should be considered. 3. Diffuse ST depression in N 6 of the inferior and anterolateral leads associated with STE in lead aVR. May indicate circumferential subendocardial ischemia due to left main stenosis or diffuse threevessel disease. Urgent coronary angiography should be considered in patients whose ECG pattern is dynamic and associated with compatible symptoms. b. Patterns without ongoing ischemia (reperfusion pattern) 1. T-wave inversion with STE. May indicate reperfusion or advanced stage of infarction. The current guidelines do not consider T-wave configuration for the indications for emergency reperfusion therapy. Further studies should be conducted. 2. Isoelectric ST with deep T-wave inversion in the precordial leads. This patter, when detected in a patient after resolution of symptoms, suggests tight narrowing of the proximal left anterior descending coronary artery. Early angiography should be considered to prevent reocclusion/reinfarction.
is indicated in such patients without STE. However, if symptoms persist despite initial medical therapy, it is probably indicated. 2 Upsloping ST depression with tall positive T waves Upsloping ST depression has not been considered to represent ischemia, as it is often seen in nonischemic individuals with tachycardia. 6 However, in some cases, upsloping ST depressions with tall positive T waves (Fig. 1) may be a manifestation of regional subendocardial ischemia. This pattern may evolve to classic STE or progress with the development of Q waves. de Winter et al. 7 suggested that 2% of patients with ACS due to LAD occlusion might have such ECG presentation. However, a similar pattern has been described with first diagonal 8 and left circumflex 9 infarctions. Many patients with ACS present with tachycardia. When seen in a patient with tachycardia, immediate differentiation between nonischemic, tachycardia-induced upsloping ST depression and acute regional subendocardial ischemia might be difficult. However, when recorded in a patient at normal heart rate, especially if the T waves are tall and symmetrical, acute ischemia should be suspected. These patients usually have tight narrowing of the culprit artery and may progress to STEMI. 7,9 Urgent coronary angiography may be indicated, especially if symptoms persist and/or the ECG evolves to STEMI. Guidelines should be changed to include upsloping ST depression (especially when followed by tall positive T waves) as a possible sign of subendocardial ischemia (in addition to horizontal or downsloping ST depression). Diffuse ST depression in six or more of the inferior and anterolateral leads associated with STE in lead aVR In patients with compatible symptoms and a relatively normal ECG at baseline (“unremarkable resting ECG“), dynamic ST depression in six leads or more together with STE in lead aVR has been associated with diffuse subendocardial ischemia caused by left main, left main equivalent or diffuse three-vessel coronary artery disease (Fig. 2). 9,10 After resolution of symptoms, ST-segment deviation may resolve and only nonspecific T-wave changes can be detected. However, this pattern is not specific and is commonly seen in patients with cardiomyopathies, left ventricular hypertrophy and left bundle branch block. 11 These patients may present with symptoms indistinguishable from acute ischemia, such as pulmonary edema, hypotension, cardiogenic shock, and so on. While in many patients the pattern of diffuse ST depression with STE in aVR is chronic, marked dynamic changes can be seen. Moreover, hypertension and ischemic cardiomyopathy are risk factors for ischemia induced by a left main narrowing or diffuse coronary artery disease. Exclusion of patients without “unremarkable resting ECG”, 10 will reduce sensitivity and applicability of this particular ECG pattern. Moreover, the document by Wagner et al. 10 did not define what is “unremarkable resting ECG.” For example, are left-axis deviation, right bundle branch block and even signs of left atrial enlargement, considered “remarkable” or “unremarkable.” We believe that adopting
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Fig. 1. A patient presenting with chest pain. ECG shows sinus rhythm and upsloping ST-segment depressions with positive T waves in leads I, II, III, aVF, and V3–V6. There is also STE in leads aVR and V1. However, per current guidelines this ECG does not qualify for acute reperfusion therapy. Color illustration online.
the recommendation by Wagner et al. 10 (“When the resting ECG reveals ST-segment depression greater than 0.1 mV (1 mm) in 8 or more body surface leads coupled with STsegment elevation in aVR and/or V1 but is otherwise
unremarkable, the automated interpretation should suggest ischemia due to multivessel or left main coronary artery obstruction.”) could lead to overdiagnosis and utilization of emergent coronary angiography.
Fig. 2. (A) An ECG of a 90-year-old male with chest pain and shortness of breath showing sinus rhythm with premature ventricular complexes. There are ST depressions with negative T waves in leads I, II, aVL, and V3–V6. There is also STE in leads aVR and V1. (B) Repeat ECG after resolution of symptoms showed sinus rhythm and right atrial enlargement. All ST deviations resolved. Coronary angiography revealed critical left main narrowing and patient underwent coronary artery bypass surgery. Color illustration online.
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Fig. 3. An ECG of a 56-year-old woman. Chest pain started 4 h before presentation. The severity of pain decreased after receiving aspirin. ECG shows sinus rhythm. There are Q waves in the inferior leads. There is minimal ST elevation with terminal T-wave inversion in the inferior leads. There is also T-wave inversion in leads V3–V6. This ECG most probably represents reperfused STEMI. Per current guidelines emergency reperfusion therapy is still indicated, as patient presented within 12 h of onset of symptoms and her ECG shows STE.
Patterns without ongoing ischemia (reperfusion pattern) T-wave inversion with STE T-wave inversion (TWI) is considered to be a sign of reperfusion, especially if accompanied by a decrease in the magnitude of STE in the early stages of STEMI. On the other hand, T-wave inversion occurs within days in patients with STE myocardial infarction even without reperfusion and represents a more advanced stage of infarction. The prognostic significance of TWI in leads with STE, before initiation of reperfusion therapy is unclear. If TWI occurs early after the onset of symptoms it might be associated with a good prognosis. 12 However, if seen in patients with late presentation it may signify completion of infarction and a poorer prognosis. 12–14 The current guidelines recommend acute reperfu-
sion therapy for patients with STE (irrespective of the Twave configuration) who present within 12 h of onset of symptoms (even if symptoms have subsided) or if there are clinical and/or ECG signs of ongoing ischemia after 12 h. 1,2 It is unclear whether reperfusion therapy with emergency primary percutaneous intervention saves myocardium in such cases, or whether it is indicated to reduce the risk of reocclusion and reinfarction (in such cases intervention may be done on an elective basis during the course of the hospitalization and not within 90 min of presentation) (Fig. 3). Further prospective studies are needed to resolve this issue. Deep T-wave inversion in the precordial leads (Wellens' sign) A pattern of deep negative T waves with minimal ST deviation in the precordial leads has been described by de
Fig. 4. ECG of a 66-year-old male after resolution of chest pain. There is minimal ST depression with T-wave inversion in leads I, aVL and V2–V6. Coronary angiography revealed a tight lesion in the proximal left anterior descending coronary artery.
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Zwaan et al. in patients after resolution of symptoms (Fig. 4). This pattern has been associated with reperfusion of a tight proximal LAD lesion. 4,9,15 Although this pattern is not associated with active ongoing ischemia, there is a high risk for artery reocclusion and transition to STEMI. 15 Therefore, urgent coronary angiography with possible stenting is indicated to prevent this transformation. Non-STE-ACS is a dynamic process. The intracoronary thrombus may expand and dissolve. Vasospasm and shedding of distal emboli from the culprit thrombus may lead to fluctuation in the extent and severity of ischemia. Repeating ECG recordings when changes in the clinical picture are noted (worsening or improvement of symptoms) may lead to better detection and understanding of the ischemic process. It should be remembered that patients could transition between non-STE-ACS and STEMI. At times, distinction between ischemic and nonischemic causes of ST deviation cannot be made and utilization of other modalities, such as echocardiography may be needed. Patients with high likelihood of ACS whose ECGs show a high-risk pattern should be treated more aggressively and coronary angiography should be recommended early to halt the progression of necrosis and/or prevent hemodynamic deterioration, or to avoid reocclusion of the culprit lesion and reinfarction. It should be emphasized that the accuracy of the ECG interpretation is enhanced when the clinical data, including risk factors, quality and severity of symptoms while the ECG was recorded are taken into consideration. These data should be recorded and stored with the ECG.
References 1. O'Gara PT, Kushner FG, Ascheim DD, et al. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association task force on practice guidelines. Circulation 2013;127:e362. 2. Steg PG, James SK, Atar D, et al. ESC guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation. Eur Heart J 2012;33:2569.
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3. Huang HD, Birnbaum Y. ST elevation: differentiation between ST elevation myocardial infarction and nonischemic ST elevation. J Electrocardiol 2011;44:494 e1. 4. Birnbaum Y, Bayes de Luna A, Fiol M, et al. Common pitfalls in the interpretation of electrocardiograms from patients with acute coronary syndromes with narrow QRS: a consensus report. Electrocardiol 2012;45:463. 5. Sagie A, Sclarovsky S, Strasberg B, et al. Acute anterior wall myocardial infarction presenting with positive T waves and without ST segment shift. Electrocardiographic features and angiographic correlation. Chest 1989;95:1211. 6. Thygesen K, Alpert JS, Jaffe AS, Simoons ML, Chaitman BR, White HD. Third universal definition of myocardial infarction. Eur Heart J 2012;33:2551. 7. de Winter RJ, Verouden NJ, Wellens HJ, Wilde AA. A new ECG sign of proximal LAD occlusion. N Engl J Med 2008;359:2071. 8. Sclarovsky S, Birnbaum Y, Solodky A, Zafrir N, Wurzel M, Rechavia E. Isolated mid-anterior myocardial infarction: a special electrocardiographic sub-type of acute myocardial infarction consisting of STelevation in non-consecutive leads and two different morphologic types of ST-depression. Int J Cardiol 1994;46:37. 9. Nikus K, Pahlm O, Wagner G, et al. Electrocardiographic classification of acute coronary syndromes: a review by a committee of the international society for Holter and non-invasive electrocardiology. J Electrocardiol 2010;43:91. 10. Wagner GS, Macfarlane P, Wellens H, et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part VI: acute ischemia/infarction: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Endorsed by the International Society for Computerized Electrocardiology. J Am Coll Cardiol 2009;53:1003. 11. Knotts RJ, Wilson JM, Kim E, Huang HD, Birnbaum Y. Diffuse ST depression with ST elevation in aVR: is this pattern specific for global ischemia due to left main coronary artery disease? J Electrocardiol 2013;46:240. 12. Herz I, Birnbaum Y, Zlotikamien B, et al. The prognostic implications of negative T waves in the leads with ST segment elevation on admission in acute myocardial infarction. Cardiology 1999;92:121. 13. Huang HD, Birnbaum I, Birnbaum Y. The double edged T wave. J Electrocardiol 2013;46:8. 14. Shimada YJ, Po JR, Kanei Y, Schweitzer P. Prognostic impact of terminal T wave inversions on presentation in patients with STelevation myocardial infarction undergoing urgent percutaneous coronary intervention. J Electrocardiol 2013;46:2. 15. de Zwaan C, Bar FW, Wellens HJ. Characteristic electrocardiographic pattern indicating a critical stenosis high in left anterior descending coronary artery in patients admitted because of impending myocardial infarction. Am Heart J 1982;103:730.
ScienceDirect Journal of Electrocardiology 46 (2013) 535 – 539 www.jecgonline.com
High-risk ECG patterns in ACS—Need for guideline revision Itamar Birnbaum, MD, a Yochai Birnbaum, MD b,⁎ a
The Department of Medicine, Baylor College of Medicine and St Luke Episcopal Hospital, Houston, TX, USA b The Section of Cardiology, Baylor College of Medicine and St Luke Episcopal Hospital. Houston, TX, USA
Abstract
The current guidelines advocate distinct approaches (urgent reperfusion therapy) to patients with suspected acute coronary syndromes (ACS) presenting with ST elevation (STE) versus patients without STE on their electrocardiogram (ECG). This is based on the paradigm that STE represents ongoing transmural ischemia due to an acute occlusion of an epicardial coronary artery whereas the significance of other ECG findings is more contentious. The role of urgent coronary angiography in patients without STE is less clear and initial stabilization with conservative treatment is recommended. However, in some cases the distinction between STEMI and non-STE-ACS is difficult. Acute occlusion of a coronary artery may cause less than the current recommended threshold STE. On the other hand, many patients may have STE secondary to nonischemic etiology. In many patients with non-STE-ACS the coronary artery is not completely occluded at the time of presentation and there are rapid fluctuations in the severity of ischemia and hence, dynamic changes are observed in the ECG. Several ECG patterns associated with particular coronary anatomy and high-risk prognosis have been identified. Patients with ACS presenting with these high-risk patterns should probably be referred for coronary angiography with the possibility of urgent intervention with the goal of prevention of ischemic complications, rather than for immediate myocardial salvage, as in classic STEMI. © 2013 Elsevier Inc. All rights reserved.
Keywords:
ECG; ACS; Guideline revision
Introduction The current guidelines make a clear distinction in the triage and initial management of patients presenting with symptoms suggestive of acute coronary syndrome (ACS) with and without ST elevation (STE) in their presenting ECG. 1,2 STE is thought to manifest ongoing transmural ischemia due to an acute occlusion of a coronary artery. Emergent reperfusion therapy is indicated to “save” myocardium and limit the ischemic damage. Tremendous effort has been invested to shorten the time from initiation of symptoms (or presentation) to reperfusion. The current guidelines suggest that patients presenting without STE can be initially managed conservatively and coronary angiography can be performed later to prevent reinfarction, but not to save myocardium. However, many patients presenting with chest pain may have STE secondary to nonischemic etiologies. 3 Many classic patterns of nonischemic STE can be easily identified (early repolarization, normal pattern, pericarditis, etc). How⁎ Corresponding author. The Section of Cardiology, Baylor College of Medicine, MS: BCM620, One Baylor Plaza, Houston, TX 77030. E-mail address: [email protected] 0022-0736/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jelectrocard.2013.06.008
ever, it should be remembered that the magnitude and distribution of these nonischemic STE patterns may dramatically change over time. For example, the magnitude of STE secondary to early repolarization tends to diminish with tachycardia, whereas STE secondary to aneurysm or left bundle branch block may increase with tachycardia. On the other hand, some patients with an acute occlusion of a coronary artery with ongoing ischemia may have borderline STE or no STE at all. 2 The European guidelines suggest that ongoing suspicion of myocardial ischemia, despite medical therapy, is an indication for emergency coronary angiography, even in patients presenting without STE. 2 In theory, patients presenting with STE have ongoing ischemia and ongoing necrosis that should be stopped by emergency revascularization. On the other hand, patients with ACS without STE may show diverse angiographic and clinical findings that may signify incomplete and dynamic occlusions. In many patients, symptoms diminish by the time of presentation. In these patients, the ECG is not expected to show acute ischemic changes or localize the site of coronary thrombus. In such instances, the ECG may show the “footprints” of previous ischemia—(terminal) T-wave inversions with insignificant ST deviation. However, if an
536
I. Birnbaum, Y. Birnbaum / Journal of Electrocardiology 46 (2013) 535–539
ECG is recorded during an episode of active symptoms, dynamic changes indicating ischemia can be detected. Thus, it is crucial to interpret the ECG while knowing the clinical data and especially whether or not the patient was symptomatic when the recording was done. Currently, the severity and/or quality of symptoms cannot be stored in the digital database. Future ECG machines should include a method to enter this information, along with the demographic data when the ECG is recorded. Several high-risk ECG patterns have been described in patients with non-STE-ACS. 4 These patterns can be divided into those with ongoing ischemia (that do not result in STE) and those without ongoing ischemia (reperfusion of a culprit lesion with high-risk features) (Table 1):
Patterns with ongoing ischemia Tall positive T waves without significant ST deviation The first sign of acute ischemia is an increase in the amplitude of the T waves. This usually precedes STE. In some patients, STE does not occur and the only manifestation of ischemia is tall, symmetric T waves. It has been suggested that persistent tall T waves without STE is seen in patients with good collateral circulation that “protects” the myocardium. 5 This pattern may be difficult to diagnose on presentation, as there are wide variations in the amplitude of the T waves and factors other than ischemia (heart rate, potassium levels, etc) may interplay. Usually, this pattern is recognized only after subsequent ECG changes are noted upon progression or alleviation of ischemia (development of Q waves, shortening of the R waves and/or T-wave inversion). It is unclear whether emergency coronary angiography
Table 1 ECG patterns associated with high risk. a. Ongoing ischemia 1. Isoelectric ST segment with tall positive T waves. If dynamic changes and not associated with hyperkalemia, consider tight occlusion of an epicardial artery. The role of emergency coronary angiography has not been established. 2. Upsloping ST depression with tall positive T waves. May indicate acute subendocardial ischemia due to tight narrowing of an epicardial artery, especially if seen in a patient without tachycardia. Urgent coronary angiography should be considered. 3. Diffuse ST depression in N 6 of the inferior and anterolateral leads associated with STE in lead aVR. May indicate circumferential subendocardial ischemia due to left main stenosis or diffuse threevessel disease. Urgent coronary angiography should be considered in patients whose ECG pattern is dynamic and associated with compatible symptoms. b. Patterns without ongoing ischemia (reperfusion pattern) 1. T-wave inversion with STE. May indicate reperfusion or advanced stage of infarction. The current guidelines do not consider T-wave configuration for the indications for emergency reperfusion therapy. Further studies should be conducted. 2. Isoelectric ST with deep T-wave inversion in the precordial leads. This patter, when detected in a patient after resolution of symptoms, suggests tight narrowing of the proximal left anterior descending coronary artery. Early angiography should be considered to prevent reocclusion/reinfarction.
is indicated in such patients without STE. However, if symptoms persist despite initial medical therapy, it is probably indicated. 2 Upsloping ST depression with tall positive T waves Upsloping ST depression has not been considered to represent ischemia, as it is often seen in nonischemic individuals with tachycardia. 6 However, in some cases, upsloping ST depressions with tall positive T waves (Fig. 1) may be a manifestation of regional subendocardial ischemia. This pattern may evolve to classic STE or progress with the development of Q waves. de Winter et al. 7 suggested that 2% of patients with ACS due to LAD occlusion might have such ECG presentation. However, a similar pattern has been described with first diagonal 8 and left circumflex 9 infarctions. Many patients with ACS present with tachycardia. When seen in a patient with tachycardia, immediate differentiation between nonischemic, tachycardia-induced upsloping ST depression and acute regional subendocardial ischemia might be difficult. However, when recorded in a patient at normal heart rate, especially if the T waves are tall and symmetrical, acute ischemia should be suspected. These patients usually have tight narrowing of the culprit artery and may progress to STEMI. 7,9 Urgent coronary angiography may be indicated, especially if symptoms persist and/or the ECG evolves to STEMI. Guidelines should be changed to include upsloping ST depression (especially when followed by tall positive T waves) as a possible sign of subendocardial ischemia (in addition to horizontal or downsloping ST depression). Diffuse ST depression in six or more of the inferior and anterolateral leads associated with STE in lead aVR In patients with compatible symptoms and a relatively normal ECG at baseline (“unremarkable resting ECG“), dynamic ST depression in six leads or more together with STE in lead aVR has been associated with diffuse subendocardial ischemia caused by left main, left main equivalent or diffuse three-vessel coronary artery disease (Fig. 2). 9,10 After resolution of symptoms, ST-segment deviation may resolve and only nonspecific T-wave changes can be detected. However, this pattern is not specific and is commonly seen in patients with cardiomyopathies, left ventricular hypertrophy and left bundle branch block. 11 These patients may present with symptoms indistinguishable from acute ischemia, such as pulmonary edema, hypotension, cardiogenic shock, and so on. While in many patients the pattern of diffuse ST depression with STE in aVR is chronic, marked dynamic changes can be seen. Moreover, hypertension and ischemic cardiomyopathy are risk factors for ischemia induced by a left main narrowing or diffuse coronary artery disease. Exclusion of patients without “unremarkable resting ECG”, 10 will reduce sensitivity and applicability of this particular ECG pattern. Moreover, the document by Wagner et al. 10 did not define what is “unremarkable resting ECG.” For example, are left-axis deviation, right bundle branch block and even signs of left atrial enlargement, considered “remarkable” or “unremarkable.” We believe that adopting
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Fig. 1. A patient presenting with chest pain. ECG shows sinus rhythm and upsloping ST-segment depressions with positive T waves in leads I, II, III, aVF, and V3–V6. There is also STE in leads aVR and V1. However, per current guidelines this ECG does not qualify for acute reperfusion therapy. Color illustration online.
the recommendation by Wagner et al. 10 (“When the resting ECG reveals ST-segment depression greater than 0.1 mV (1 mm) in 8 or more body surface leads coupled with STsegment elevation in aVR and/or V1 but is otherwise
unremarkable, the automated interpretation should suggest ischemia due to multivessel or left main coronary artery obstruction.”) could lead to overdiagnosis and utilization of emergent coronary angiography.
Fig. 2. (A) An ECG of a 90-year-old male with chest pain and shortness of breath showing sinus rhythm with premature ventricular complexes. There are ST depressions with negative T waves in leads I, II, aVL, and V3–V6. There is also STE in leads aVR and V1. (B) Repeat ECG after resolution of symptoms showed sinus rhythm and right atrial enlargement. All ST deviations resolved. Coronary angiography revealed critical left main narrowing and patient underwent coronary artery bypass surgery. Color illustration online.
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Fig. 3. An ECG of a 56-year-old woman. Chest pain started 4 h before presentation. The severity of pain decreased after receiving aspirin. ECG shows sinus rhythm. There are Q waves in the inferior leads. There is minimal ST elevation with terminal T-wave inversion in the inferior leads. There is also T-wave inversion in leads V3–V6. This ECG most probably represents reperfused STEMI. Per current guidelines emergency reperfusion therapy is still indicated, as patient presented within 12 h of onset of symptoms and her ECG shows STE.
Patterns without ongoing ischemia (reperfusion pattern) T-wave inversion with STE T-wave inversion (TWI) is considered to be a sign of reperfusion, especially if accompanied by a decrease in the magnitude of STE in the early stages of STEMI. On the other hand, T-wave inversion occurs within days in patients with STE myocardial infarction even without reperfusion and represents a more advanced stage of infarction. The prognostic significance of TWI in leads with STE, before initiation of reperfusion therapy is unclear. If TWI occurs early after the onset of symptoms it might be associated with a good prognosis. 12 However, if seen in patients with late presentation it may signify completion of infarction and a poorer prognosis. 12–14 The current guidelines recommend acute reperfu-
sion therapy for patients with STE (irrespective of the Twave configuration) who present within 12 h of onset of symptoms (even if symptoms have subsided) or if there are clinical and/or ECG signs of ongoing ischemia after 12 h. 1,2 It is unclear whether reperfusion therapy with emergency primary percutaneous intervention saves myocardium in such cases, or whether it is indicated to reduce the risk of reocclusion and reinfarction (in such cases intervention may be done on an elective basis during the course of the hospitalization and not within 90 min of presentation) (Fig. 3). Further prospective studies are needed to resolve this issue. Deep T-wave inversion in the precordial leads (Wellens' sign) A pattern of deep negative T waves with minimal ST deviation in the precordial leads has been described by de
Fig. 4. ECG of a 66-year-old male after resolution of chest pain. There is minimal ST depression with T-wave inversion in leads I, aVL and V2–V6. Coronary angiography revealed a tight lesion in the proximal left anterior descending coronary artery.
I. Birnbaum, Y. Birnbaum / Journal of Electrocardiology 46 (2013) 535–539 15
Zwaan et al. in patients after resolution of symptoms (Fig. 4). This pattern has been associated with reperfusion of a tight proximal LAD lesion. 4,9,15 Although this pattern is not associated with active ongoing ischemia, there is a high risk for artery reocclusion and transition to STEMI. 15 Therefore, urgent coronary angiography with possible stenting is indicated to prevent this transformation. Non-STE-ACS is a dynamic process. The intracoronary thrombus may expand and dissolve. Vasospasm and shedding of distal emboli from the culprit thrombus may lead to fluctuation in the extent and severity of ischemia. Repeating ECG recordings when changes in the clinical picture are noted (worsening or improvement of symptoms) may lead to better detection and understanding of the ischemic process. It should be remembered that patients could transition between non-STE-ACS and STEMI. At times, distinction between ischemic and nonischemic causes of ST deviation cannot be made and utilization of other modalities, such as echocardiography may be needed. Patients with high likelihood of ACS whose ECGs show a high-risk pattern should be treated more aggressively and coronary angiography should be recommended early to halt the progression of necrosis and/or prevent hemodynamic deterioration, or to avoid reocclusion of the culprit lesion and reinfarction. It should be emphasized that the accuracy of the ECG interpretation is enhanced when the clinical data, including risk factors, quality and severity of symptoms while the ECG was recorded are taken into consideration. These data should be recorded and stored with the ECG.
References 1. O'Gara PT, Kushner FG, Ascheim DD, et al. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association task force on practice guidelines. Circulation 2013;127:e362. 2. Steg PG, James SK, Atar D, et al. ESC guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation. Eur Heart J 2012;33:2569.
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