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Electrocardiographic prediction of short-term prognosis in patients with acute myocardial infarction associated with the left main coronary artery
Available online at www.sciencedirect.com
Journal of Electrocardiology 42 (2009) 106 – 110 www.jecgonline.com
Electrocardiographic prediction of short-term prognosis in patients with acute myocardial infarction associated with the left main coronary artery Satoshi Kurisu, MD,⁎ Ichiro Inoue, MD, Takuji Kawagoe, MD, Masaharu Ishihara, MD, Yuji Shimatani, MD, Yasuharu Nakama, MD, Tatsuya Maruhashi, MD, Eisuke Kagawa, MD, Kazuoki Dai, MD, Junichi Matsushita, MD, Hiroki Ikenaga, MD Department of Cardiology, Hiroshima City Hospital, Hiroshima, Japan Received 7 September 2008
Abstract
Purpose: The purpose of this study was to assess the usefulness of electrocardiogram on admission to predict short-term prognosis in patients with acute myocardial infarction (AMI) associated with left main coronary artery (LMCA). Methods: Electrocardiogram was obtained on admission in 41 patients with AMI associated with LMCA who underwent reperfusion therapy. Electrocardiographic findings were compared between nonsurvivors and survivors. Results: There were 24 nonsurvivors and 17 survivors during 30-day follow-up. Nonsurvivors had ST-segment elevation in both leads aVR and aVL (54% vs 18%, P b .05), left anterior fascicular block (83% vs 41%, P b .05), and right bundle-branch block (54% vs 18%, P b .05) more frequently, and ST-segment depression in lead V5 (17% vs 59%, P b .05) less frequently than survivors among patients with AMI associated with LMCA. Conclusions: Our data suggested that electrocardiogram on admission might be useful to predict short-term prognosis in patients with AMI associated with LMCA. © 2009 Elsevier Inc. All rights reserved.
Keywords:
Left anterior fascicular block; Acute myocardial infarction; Left main coronary artery
Introduction
Methods
Acute myocardial infarction (AMI) associated with left main coronary artery (LMCA) is rare but frequently results in poor prognosis because of the extensive area at risk with anterolateral wall involvement.1-5 Twelve-lead electrocardiogram (ECG) is a routine examination in patients with chest pain, and its usefulness to diagnose AMI is established. Previous studies have demonstrated several ECG features of AMI associated with LMCA,4,6,7 but there are few reports assessing the relation between ECG features and prognosis. In the current study, we assessed the usefulness of ECG on admission to predict short-term prognosis in patients with AMI associated with LMCA.
Study patients
⁎ Corresponding author. Department of Cardiology, Hiroshima City Hospital, 7-33, Moto-machi, Naka-ku, Hiroshima 730-8518, Japan. Tel.: +81 82 221 2291; fax: +81 82 223 1447. E-mail address: [email protected] 0022-0736/$ – see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.jelectrocard.2008.10.008
Forty-one consecutive patients with AMI associated with LMCA were enrolled in this study (37 men and 4 women, aged 36-86 years [62 ± 11 years]). Acute myocardial infarction associated with LMCA was diagnosed by (1) chest pain consistent with ongoing myocardial ischemia persisting for 30 minutes or more; (2) elevation of serum creatine kinase to more than twice the normal upper limit; and (3) presence of more than 90% diameter of the stenosis in LMCA. Patients with prior myocardial infarction, left ventricular hypertrophy, or 75% stenosis or more in right coronary artery were excluded from this study. Patients with right bundle-branch block (RBBB) were included, but those with left bundle-branch block were excluded because of the difficulty of diagnosing AMI. Cardiogenic shock was defined as systolic blood pressure of less than 90 mm Hg without inotropic agents or intraaortic balloon pumping.
S. Kurisu et al. / Journal of Electrocardiology 42 (2009) 106–110
Electrocardiogram On admission, ECG was recorded at a paper speed of 25 mm/s and an amplification of 10 mm/mV. The isoelectric line was defined as the level of the preceding TP segment. STsegment deflection was measured at the J point. ST-segment elevation or depression was considered present if ST-segment deflection was 0.1 mV or more. Left anterior fascicular block (LAFB) was defined by the mean QRS axis deviated to the left less than 30°in the frontal plane. Right bundle-branch block was defined by using standard ECG criteria; a QRS duration of 120 milliseconds or more was required. Coronary angiography Coronary angiography was performed in all patients through the femoral approach. Reperfusion therapy such as intracoronary thrombolysis, balloon angioplasty, stent placement, or coronary artery bypass grafting was performed in all patients. The use of intraaortic balloon pumping or percutaneous cardiopulmonary support was based on the physician's decision. Statistics Data are expressed as the mean value ± SD. Statistical analysis was performed with the χ2 test for categorical variables. The unpaired Student t test was used for continuous variables. Differences were considered significant if the P value was less than .05. Results Patient characteristics Of 41 patients with AMI associated with LMCA, 24 patients were dead (nonsurvivors), and 17 patients were alive (survivors) during 30-day follow-up. Patient characteristics were shown in Table 1. There was no significant difference in sex, age, hypertension, or diabetes. Nonsurvivors have cardiogenic shock more frequently (83% vs 41%, P b .05), but there was no significant difference in heart rate between the 2 groups. Emergency coronary angiography revealed total occlusion in 20 patients and subtotal occlusion in 21 patients. There was no significant difference in initial perfusion status between the 2 groups. Twenty-three patients underwent percutaneous coronary intervention including intracoronary thrombolysis, balloon angioplasty, or stent placement, and the remaining 18 patients underwent coronary artery bypass grafting. Nonsurvivors underwent percutaneous coronary intervention more frequently (75% vs 29%, P b .01). Electrocardiographic findings Twelve-lead ECG on admission and coronary angiography in a patient with AMI associated with LMCA is shown in Figs. 1 and 2. The incidence of ST-segment elevation or depression in both groups was shown in Table 2. ST-segment elevation in lead aVR and ST-segment depression in inferior leads were relatively common in both groups. There was no significant difference in the incidence of ST-segment elevation in lead aVR (75% vs 53%, P = not
107
Table 1 Patient characteristics
Male sex Age Hypertension Diabetes Current smoker Cardiogenic shock Heart rate Coronary angiography Total occlusion Subtotal occlusion Reperfusion therapy PCI CABG
Nonsurvivors (n = 24)
Survivors (n = 17)
P
20 (83%) 64 ± 10 7 (29%) 4 (17%) 9 (38%) 20 (83%) 90 ± 26
17 (100%) 60 ± 11 6 (35%) 5 (29%) 10 (59%) 7 (41%) 83 ± 23
NS NS NS NS NS b.05 NS
13 (54%) 11 (46%)
7 (41%) 10 (59%)
NS
18 (75%) 6 (25%)
5 (29%) 12 (71%)
b.01
PCI indicates percutaneous coronary intervention; CABG, coronary artery bypass grafting.
significant [NS]) or in lead aVL (71% vs 41%, P = NS) between the 2 groups (Table 3). However, the incidence of ST-segment elevation in both leads aVR and aVL was significantly higher in nonsurvivors (54% vs 18%, P b .05). Although the incidence of ST-segment depression in inferior leads was similar, the incidence of ST-segment depression in lead V5 (17% vs 59%, P b .05) was significantly lower in nonsurvivors. Also, the incidence of LAFB (83% vs 41%, P b .05) or RBBB (54% vs 18%, P b .05) was significantly higher in nonsurvivors. Additional analysis was performed (Table 4) to assess the relation between these ECG findings and cardiogenic shock. There was no significant difference in the incidence of these ECG findings between patients with cardiogenic shock and those without. Discussion Present study This study demonstrated that nonsurvivors had STsegment elevation in both leads aVR and aVL, LAFB and RBBB more frequently, and ST-segment depression in lead V5 less frequently than survivors among patients with AMI associated with LMCA. Previous studies Acute myocardial infarction associated with LMCA is rare. This may be accounted for a high incidence of death in these patients. Previous studies demonstrated that the prognosis in patients with AMI associated with LMCA was dependent on the predominance of right coronary artery or the development of collateral circulation.3,4 Indeed, these anatomical factors are important to rescue these patients. If once it occurs, it is important that cardiologists make a correct diagnosis speedy and adopt an effective treatment subsequently. Electrocardiogram and AMI associated with LMCA We previously reported that ST-segment depression in inferior leads and LAFB predicted LMCA occlusion with
108
S. Kurisu et al. / Journal of Electrocardiology 42 (2009) 106–110
Fig. 1. Twelve-lead ECG on admission. The ECG showed ST-segment depression in leads I, II, aVF, and V4 to V6; ST-segment elevation in lead aVR; and LAFB.
Fig. 2. Coronary angiography before and after reperfusion therapy. Emergency coronary angiography revealed total occlusion in the LMCA (A). The patient was treated with intraaortic balloon pumping, percutaneous cardiopulmonary support, and stent placement 2 hours after the onset (B) and was discharged 35 days later.
S. Kurisu et al. / Journal of Electrocardiology 42 (2009) 106–110 Table 2 Incidence of ST-segment deviation ECG leads
I II III aVR aVL aVF V1 V2 V3 V4 V5 V6
ST-segment elevation Nonsurvivors (%)
Survivors (%)
17 4 4 75 71 4 38 42 46 42 29 13
35 0 0 53 41 0 35 65 47 18 18 12
Table 4 Electrocardiographic findings of patients with shock and those without P
NS NS NS NS NS NS NS NS NS NS NS NS
ST-segment depression Nonsurvivors (%)
Survivors (%)
13 79 83 0 8 79 17 21 17 21 17 38
18 76 59 0 0 71 0 12 24 35 59 53
P
NS NS NS NS NS NS NS NS NS NS b.05 NS
high sensitivity, and that ST-segment elevation in both leads aVR and aVL, ST-segment elevation in lead aVR with less elevation in lead V1, LAFB, and RBBB predicted LMCA occlusion with high specificity in patients with AMI.7 The relation between ECG features and prognosis in patients with AMI associated with LMCA has not been fully assessed, at least in part because it is rare. Hori et al8 assessed the relation in a small number of 13 patients and reported that 5 of 6 nonsurvivors showed ST-segment elevation in both leads aVR and aVL. In this study, we also demonstrated that nonsurvivors had ST-segment elevation in both leads aVR and aVL more frequently than survivors in a relatively large number of 41 patients. ST-segment elevation in lead aVR is known to be useful to identify LAD occlusion proximal to the first septal branch, and this finding is probably the result of transmural ischemia of the basal part of the septum.9 Lead aVL faces the basal part of the lateral free wall. The incidence of ST-segment elevation in lead aVL is low in AMI associated with left circumflex artery10 because inferior leads are opposed to lead aVL, and ECG changes in leads facing both the inferior and high lateral regions tend to cancel each other.11 However, the incidence of ST-segment elevation in lead aVL is high in AMI associated with the diagonal branch.12 Thus, ST-segment elevation in both leads aVR and aVL seems to mean transmural ischemia extending over the broad area of the left anterior descending artery. ST-segment depression in lead V5 is also known to be very specific to identify LAD occlusion proximal to the first
Nonsurvivors (n = 24)
Survivors (n = 17)
ST elevation ≥0.1 mV in aVR ST elevation ≥0.1 mV in aVL ST elevation ≥0.1 mV in both aVR and aVL ST depression ≥0.1 mV in III ST depression ≥0.1 mV in V5 LAFB RBBB
Patients with shock (n = 27)
Patients without shock (n = 14)
P
17 (63%) 17 (63%) 10 (37%)
10 (71%) 7 (50%) 6 (43%)
NS NS NS
22 (81%) 6 (22%) 19 (70%) 13 (48%)
8 (57%) 8 (57%) 8 (57%) 3 (21%)
NS NS NS NS
septal branch.9 This finding is interpreted as reciprocal change associated with transmural ischemia of the basal part of the anteroseptum. On the other hand, ST-segment elevation in lead V5 is common in AMI associated with left circumflex artery. 13-15 When transmural ischemia extends over the areas of both arteries, ECG changes in lead V5 tend to cancel each other. In this study, we demonstrated that nonsurvivors had ST-segment depression in V5 less frequently than survivors. Although there was no significant difference in initial perfusion status of LMCA between nonsurvivors and survivors, the degree of transmural ischemia and its area could be dependent on other factors such as the predominance of right coronary artery, the development of collateral circulation, or the effect of ischemic preconditioning. We could not evaluate the precise reason because of the small number of patients. However, there was a possibility that transmural ischemia extending over the areas of both arteries resulted in lower incidence of ST-segment elevation in lead V5 in nonsurvivors. Study limitations This is a retrospective study, and there are several limitations of this study. First, we assessed collateral circulation in only 20 patients who had stable hemodynamics, and we could not assess the impact of collateral circulation on clinical outcome. Second, patients were selected from our database of emergency coronary angiography for analysis, and patients who died before coronary angiography were excluded. Therefore, the mortality rate may be underestimated. Third, percutaneous coronary intervention was often allocated in patients with cardiogenic shock to obtain as early reperfusion as possible. As a result, nonsurvivors underwent percutaneous coronary intervention more frequently. Clinical implications
Table 3 Electrocardiographic findings of nonsurvivors and survivors
ST elevation ≥0.1 mV in aVR ST elevation ≥0.1 mV in aVL ST elevation ≥0.1 mV in both aVR and aVL ST depression ≥0.1 mV in III ST depression ≥0.1 mV in V5 LAFB RBBB
109
P
18 (75%) 17 (71%) 13 (54%)
9 (53%) 7 (41%) 3 (18%)
NS NS b.05
20 (83%) 4 (17%) 20 (83%) 13 (54%)
10 (59%) 10 (59%) 7 (41%) 3 (18%)
NS b.05 b.05 b.05
Nowadays, transthoracic echocardiography as well as ECG is a routine examination in patients with chest pain, and cardiologists can diagnose AMI associated with LMCA speedy with these examinations. This study demonstrated that ECG on admission might be also useful to predict shortterm prognosis in patients with AMI associated with LMCA. Further studies are necessary to clarify whether patients with ECG findings shown in this study benefit from a more aggressive, adjunctive treatment such as intraaortic balloon pumping or percutaneous cardiopulmonary support.
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Conclusion Our data suggested that ECG on admission might be useful to predict short-term prognosis in patients with AMI associated with LMCA. References 1. de Feyter PJ, Serruys PW. Thrombolysis of acute total occlusion of the left main coronary artery in evolving myocardial infarction. Am J Cardiol 1984;53:1727. 2. Weyne AE, Colardyn FA, Heyndrickx GR, Clement DL. Survival after acute myocardial infarction associated with total obstruction of left main coronary artery. Am J Cardiol 1985;55:1423. 3. Cohen MC, Fergson DW. Survival after acute myocardial infarction caused by acute left main coronary artery occlusion: case report and review of the literature. Cathet Cardiovasc Diagn 1989;16:230. 4. Iwasaki K, Kusachi S, Hina K, et al. Acute left main coronary artery obstruction with myocardial infarction: reperfusion strategies, and the clinical and angiographic outcome. Jpn Circ J 1993;57:891. 5. Spiecker M, Erbel R, Rupprecht HJ, Meyer J. Emergency angioplasty of totally occluded left main coronary artery in acute myocardial infarction and unstable angina pectoris: institutional experience and literature review. Eur Heart J 1994;15:602. 6. Yamaji H, Iwasaki K, Kusachi S, et al. Prediction of acute left main coronary artery obstruction by 12-lead electrocardiography: ST segment elevation in lead aVR with less ST segment elevation in lead V1. J Am Coll Cardiol 2001;38:1348. 7. Kurisu S, Inoue I, Kawagoe T, et al. Electrocardiographic features in patients with acute myocardial infarction associated with left main coronary artery occlusion. Heart 2004;90:1059.
8. Hori T, Kurosawa T, Yoshida M, Yamazoe M, Aizawa Y, Izumi T. Factors predicting mortality in patients after myocardial infarction caused by left main coronary artery occlusion: significance of ST segment elevation in both aVR and aVL leads. Jpn Heart J 2000;41: 571. 9. Engelen DJ, Gorgels AP, Cheriex EC, et al. Value of the electrocardiogram in localizing the occlusion site in the left anterior descending coronary artery in acute anterior myocardial infarction. J Am Coll Cardiol 1999;34:389. 10. Huey BL, Beller GA, Kaizer DL, Gibson RS. A comprehensive analysis of myocardial infarction due to left circumflex artery occlusion: comparison with infarction due to right coronary artery and left anterior descending artery occlusion. J Am Coll Cardiol 1988; 12:1156. 11. Birnbaum Y, Sclarovsky S, Mager A, Strasberg B, Rechavia E. ST segment depression in aVL: a sensitive marker for acute inferior myocardial infarction. Eur Heart J 1993;14:4. 12. Iwasaki K, Kusachi S, Kita T, Taniguchi G. Prediction of isolated first diagonal branch occlusion by 12-lead electrocardiography: ST segment shift in leads I and aVL. J Am Coll Cardiol 1994;23:1557. 13. Bairey CN, Shah PK, Lew AS, Hulse S. Electrocardiographic differentiation of occlusion of the circumflex versus the right coronary artery as a cause of inferior acute myocardial infarction. Am J Cardiol 1987;60:456. 14. Wong CK, Freedman SB. Electrocardiographic identification of the infarct-related artery in acute inferior myocardial myocardial infarction. Int J Cardiol 1996;54:5. 15. Wong TW, Huang XH, Liu W, Ng K, Ng KS. New electrocardiographic criteria for identifying the culprit artery in inferior wall acute myocardial infarction: usefulness of T-wave amplitude ratio in leads II/III and T-wave polarity in the right V5 lead. Am J Cardiol 2004;94: 1168.
Journal of Electrocardiology 42 (2009) 106 – 110 www.jecgonline.com
Electrocardiographic prediction of short-term prognosis in patients with acute myocardial infarction associated with the left main coronary artery Satoshi Kurisu, MD,⁎ Ichiro Inoue, MD, Takuji Kawagoe, MD, Masaharu Ishihara, MD, Yuji Shimatani, MD, Yasuharu Nakama, MD, Tatsuya Maruhashi, MD, Eisuke Kagawa, MD, Kazuoki Dai, MD, Junichi Matsushita, MD, Hiroki Ikenaga, MD Department of Cardiology, Hiroshima City Hospital, Hiroshima, Japan Received 7 September 2008
Abstract
Purpose: The purpose of this study was to assess the usefulness of electrocardiogram on admission to predict short-term prognosis in patients with acute myocardial infarction (AMI) associated with left main coronary artery (LMCA). Methods: Electrocardiogram was obtained on admission in 41 patients with AMI associated with LMCA who underwent reperfusion therapy. Electrocardiographic findings were compared between nonsurvivors and survivors. Results: There were 24 nonsurvivors and 17 survivors during 30-day follow-up. Nonsurvivors had ST-segment elevation in both leads aVR and aVL (54% vs 18%, P b .05), left anterior fascicular block (83% vs 41%, P b .05), and right bundle-branch block (54% vs 18%, P b .05) more frequently, and ST-segment depression in lead V5 (17% vs 59%, P b .05) less frequently than survivors among patients with AMI associated with LMCA. Conclusions: Our data suggested that electrocardiogram on admission might be useful to predict short-term prognosis in patients with AMI associated with LMCA. © 2009 Elsevier Inc. All rights reserved.
Keywords:
Left anterior fascicular block; Acute myocardial infarction; Left main coronary artery
Introduction
Methods
Acute myocardial infarction (AMI) associated with left main coronary artery (LMCA) is rare but frequently results in poor prognosis because of the extensive area at risk with anterolateral wall involvement.1-5 Twelve-lead electrocardiogram (ECG) is a routine examination in patients with chest pain, and its usefulness to diagnose AMI is established. Previous studies have demonstrated several ECG features of AMI associated with LMCA,4,6,7 but there are few reports assessing the relation between ECG features and prognosis. In the current study, we assessed the usefulness of ECG on admission to predict short-term prognosis in patients with AMI associated with LMCA.
Study patients
⁎ Corresponding author. Department of Cardiology, Hiroshima City Hospital, 7-33, Moto-machi, Naka-ku, Hiroshima 730-8518, Japan. Tel.: +81 82 221 2291; fax: +81 82 223 1447. E-mail address: [email protected] 0022-0736/$ – see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.jelectrocard.2008.10.008
Forty-one consecutive patients with AMI associated with LMCA were enrolled in this study (37 men and 4 women, aged 36-86 years [62 ± 11 years]). Acute myocardial infarction associated with LMCA was diagnosed by (1) chest pain consistent with ongoing myocardial ischemia persisting for 30 minutes or more; (2) elevation of serum creatine kinase to more than twice the normal upper limit; and (3) presence of more than 90% diameter of the stenosis in LMCA. Patients with prior myocardial infarction, left ventricular hypertrophy, or 75% stenosis or more in right coronary artery were excluded from this study. Patients with right bundle-branch block (RBBB) were included, but those with left bundle-branch block were excluded because of the difficulty of diagnosing AMI. Cardiogenic shock was defined as systolic blood pressure of less than 90 mm Hg without inotropic agents or intraaortic balloon pumping.
S. Kurisu et al. / Journal of Electrocardiology 42 (2009) 106–110
Electrocardiogram On admission, ECG was recorded at a paper speed of 25 mm/s and an amplification of 10 mm/mV. The isoelectric line was defined as the level of the preceding TP segment. STsegment deflection was measured at the J point. ST-segment elevation or depression was considered present if ST-segment deflection was 0.1 mV or more. Left anterior fascicular block (LAFB) was defined by the mean QRS axis deviated to the left less than 30°in the frontal plane. Right bundle-branch block was defined by using standard ECG criteria; a QRS duration of 120 milliseconds or more was required. Coronary angiography Coronary angiography was performed in all patients through the femoral approach. Reperfusion therapy such as intracoronary thrombolysis, balloon angioplasty, stent placement, or coronary artery bypass grafting was performed in all patients. The use of intraaortic balloon pumping or percutaneous cardiopulmonary support was based on the physician's decision. Statistics Data are expressed as the mean value ± SD. Statistical analysis was performed with the χ2 test for categorical variables. The unpaired Student t test was used for continuous variables. Differences were considered significant if the P value was less than .05. Results Patient characteristics Of 41 patients with AMI associated with LMCA, 24 patients were dead (nonsurvivors), and 17 patients were alive (survivors) during 30-day follow-up. Patient characteristics were shown in Table 1. There was no significant difference in sex, age, hypertension, or diabetes. Nonsurvivors have cardiogenic shock more frequently (83% vs 41%, P b .05), but there was no significant difference in heart rate between the 2 groups. Emergency coronary angiography revealed total occlusion in 20 patients and subtotal occlusion in 21 patients. There was no significant difference in initial perfusion status between the 2 groups. Twenty-three patients underwent percutaneous coronary intervention including intracoronary thrombolysis, balloon angioplasty, or stent placement, and the remaining 18 patients underwent coronary artery bypass grafting. Nonsurvivors underwent percutaneous coronary intervention more frequently (75% vs 29%, P b .01). Electrocardiographic findings Twelve-lead ECG on admission and coronary angiography in a patient with AMI associated with LMCA is shown in Figs. 1 and 2. The incidence of ST-segment elevation or depression in both groups was shown in Table 2. ST-segment elevation in lead aVR and ST-segment depression in inferior leads were relatively common in both groups. There was no significant difference in the incidence of ST-segment elevation in lead aVR (75% vs 53%, P = not
107
Table 1 Patient characteristics
Male sex Age Hypertension Diabetes Current smoker Cardiogenic shock Heart rate Coronary angiography Total occlusion Subtotal occlusion Reperfusion therapy PCI CABG
Nonsurvivors (n = 24)
Survivors (n = 17)
P
20 (83%) 64 ± 10 7 (29%) 4 (17%) 9 (38%) 20 (83%) 90 ± 26
17 (100%) 60 ± 11 6 (35%) 5 (29%) 10 (59%) 7 (41%) 83 ± 23
NS NS NS NS NS b.05 NS
13 (54%) 11 (46%)
7 (41%) 10 (59%)
NS
18 (75%) 6 (25%)
5 (29%) 12 (71%)
b.01
PCI indicates percutaneous coronary intervention; CABG, coronary artery bypass grafting.
significant [NS]) or in lead aVL (71% vs 41%, P = NS) between the 2 groups (Table 3). However, the incidence of ST-segment elevation in both leads aVR and aVL was significantly higher in nonsurvivors (54% vs 18%, P b .05). Although the incidence of ST-segment depression in inferior leads was similar, the incidence of ST-segment depression in lead V5 (17% vs 59%, P b .05) was significantly lower in nonsurvivors. Also, the incidence of LAFB (83% vs 41%, P b .05) or RBBB (54% vs 18%, P b .05) was significantly higher in nonsurvivors. Additional analysis was performed (Table 4) to assess the relation between these ECG findings and cardiogenic shock. There was no significant difference in the incidence of these ECG findings between patients with cardiogenic shock and those without. Discussion Present study This study demonstrated that nonsurvivors had STsegment elevation in both leads aVR and aVL, LAFB and RBBB more frequently, and ST-segment depression in lead V5 less frequently than survivors among patients with AMI associated with LMCA. Previous studies Acute myocardial infarction associated with LMCA is rare. This may be accounted for a high incidence of death in these patients. Previous studies demonstrated that the prognosis in patients with AMI associated with LMCA was dependent on the predominance of right coronary artery or the development of collateral circulation.3,4 Indeed, these anatomical factors are important to rescue these patients. If once it occurs, it is important that cardiologists make a correct diagnosis speedy and adopt an effective treatment subsequently. Electrocardiogram and AMI associated with LMCA We previously reported that ST-segment depression in inferior leads and LAFB predicted LMCA occlusion with
108
S. Kurisu et al. / Journal of Electrocardiology 42 (2009) 106–110
Fig. 1. Twelve-lead ECG on admission. The ECG showed ST-segment depression in leads I, II, aVF, and V4 to V6; ST-segment elevation in lead aVR; and LAFB.
Fig. 2. Coronary angiography before and after reperfusion therapy. Emergency coronary angiography revealed total occlusion in the LMCA (A). The patient was treated with intraaortic balloon pumping, percutaneous cardiopulmonary support, and stent placement 2 hours after the onset (B) and was discharged 35 days later.
S. Kurisu et al. / Journal of Electrocardiology 42 (2009) 106–110 Table 2 Incidence of ST-segment deviation ECG leads
I II III aVR aVL aVF V1 V2 V3 V4 V5 V6
ST-segment elevation Nonsurvivors (%)
Survivors (%)
17 4 4 75 71 4 38 42 46 42 29 13
35 0 0 53 41 0 35 65 47 18 18 12
Table 4 Electrocardiographic findings of patients with shock and those without P
NS NS NS NS NS NS NS NS NS NS NS NS
ST-segment depression Nonsurvivors (%)
Survivors (%)
13 79 83 0 8 79 17 21 17 21 17 38
18 76 59 0 0 71 0 12 24 35 59 53
P
NS NS NS NS NS NS NS NS NS NS b.05 NS
high sensitivity, and that ST-segment elevation in both leads aVR and aVL, ST-segment elevation in lead aVR with less elevation in lead V1, LAFB, and RBBB predicted LMCA occlusion with high specificity in patients with AMI.7 The relation between ECG features and prognosis in patients with AMI associated with LMCA has not been fully assessed, at least in part because it is rare. Hori et al8 assessed the relation in a small number of 13 patients and reported that 5 of 6 nonsurvivors showed ST-segment elevation in both leads aVR and aVL. In this study, we also demonstrated that nonsurvivors had ST-segment elevation in both leads aVR and aVL more frequently than survivors in a relatively large number of 41 patients. ST-segment elevation in lead aVR is known to be useful to identify LAD occlusion proximal to the first septal branch, and this finding is probably the result of transmural ischemia of the basal part of the septum.9 Lead aVL faces the basal part of the lateral free wall. The incidence of ST-segment elevation in lead aVL is low in AMI associated with left circumflex artery10 because inferior leads are opposed to lead aVL, and ECG changes in leads facing both the inferior and high lateral regions tend to cancel each other.11 However, the incidence of ST-segment elevation in lead aVL is high in AMI associated with the diagonal branch.12 Thus, ST-segment elevation in both leads aVR and aVL seems to mean transmural ischemia extending over the broad area of the left anterior descending artery. ST-segment depression in lead V5 is also known to be very specific to identify LAD occlusion proximal to the first
Nonsurvivors (n = 24)
Survivors (n = 17)
ST elevation ≥0.1 mV in aVR ST elevation ≥0.1 mV in aVL ST elevation ≥0.1 mV in both aVR and aVL ST depression ≥0.1 mV in III ST depression ≥0.1 mV in V5 LAFB RBBB
Patients with shock (n = 27)
Patients without shock (n = 14)
P
17 (63%) 17 (63%) 10 (37%)
10 (71%) 7 (50%) 6 (43%)
NS NS NS
22 (81%) 6 (22%) 19 (70%) 13 (48%)
8 (57%) 8 (57%) 8 (57%) 3 (21%)
NS NS NS NS
septal branch.9 This finding is interpreted as reciprocal change associated with transmural ischemia of the basal part of the anteroseptum. On the other hand, ST-segment elevation in lead V5 is common in AMI associated with left circumflex artery. 13-15 When transmural ischemia extends over the areas of both arteries, ECG changes in lead V5 tend to cancel each other. In this study, we demonstrated that nonsurvivors had ST-segment depression in V5 less frequently than survivors. Although there was no significant difference in initial perfusion status of LMCA between nonsurvivors and survivors, the degree of transmural ischemia and its area could be dependent on other factors such as the predominance of right coronary artery, the development of collateral circulation, or the effect of ischemic preconditioning. We could not evaluate the precise reason because of the small number of patients. However, there was a possibility that transmural ischemia extending over the areas of both arteries resulted in lower incidence of ST-segment elevation in lead V5 in nonsurvivors. Study limitations This is a retrospective study, and there are several limitations of this study. First, we assessed collateral circulation in only 20 patients who had stable hemodynamics, and we could not assess the impact of collateral circulation on clinical outcome. Second, patients were selected from our database of emergency coronary angiography for analysis, and patients who died before coronary angiography were excluded. Therefore, the mortality rate may be underestimated. Third, percutaneous coronary intervention was often allocated in patients with cardiogenic shock to obtain as early reperfusion as possible. As a result, nonsurvivors underwent percutaneous coronary intervention more frequently. Clinical implications
Table 3 Electrocardiographic findings of nonsurvivors and survivors
ST elevation ≥0.1 mV in aVR ST elevation ≥0.1 mV in aVL ST elevation ≥0.1 mV in both aVR and aVL ST depression ≥0.1 mV in III ST depression ≥0.1 mV in V5 LAFB RBBB
109
P
18 (75%) 17 (71%) 13 (54%)
9 (53%) 7 (41%) 3 (18%)
NS NS b.05
20 (83%) 4 (17%) 20 (83%) 13 (54%)
10 (59%) 10 (59%) 7 (41%) 3 (18%)
NS b.05 b.05 b.05
Nowadays, transthoracic echocardiography as well as ECG is a routine examination in patients with chest pain, and cardiologists can diagnose AMI associated with LMCA speedy with these examinations. This study demonstrated that ECG on admission might be also useful to predict shortterm prognosis in patients with AMI associated with LMCA. Further studies are necessary to clarify whether patients with ECG findings shown in this study benefit from a more aggressive, adjunctive treatment such as intraaortic balloon pumping or percutaneous cardiopulmonary support.
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