Medical Journal Review: Comparing QRS, ST and T with LBBB and MI

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Hello, In this paper I need from 3 to 4 paragraphs that review (NOT analyze) the study. The analysis of the main study shouldn't take more that 1/4 of the whole paper. The rest of the paper has to be your own opinion about the topic and the findings with supporting your opinion with reliable resources.


why do you think this topic is important?

what do you think about the study and the findings?

how is the criteria was used in the research is accurate?

Sgarbossa criteria vs. modified Sgarbossa criteria, etc.

I am attaching the main journal, and the Journal Article Grading Rubric (you should follow it):

Use APA format and follow the grading rubric for more details about the assignment.

extra sources: you need to understand the topic before you start writing. this is the second request for the same journal after I withdraw the first one because the writer was not knowledgeable about the topic and some terms that are mentioned in the journal. PLEASE understand the main purpose of this journal and start from there.




NOTE" cite your sources that support your opinion

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Journal Article Grading Rubric 2 1 0 Length 3-4 paragraphs. Somewhat too long or Much too long or short. Reference, and article short. Reference or No reference or article Basic or URL given. article/URL given. Small given. Terminology, Technical terminology Mechanics number of errors in formalism frequently and formalism are terminology or formalism. misused. used correctly. Chosen point identified and clearly No point identified, or explained. Factually Chosen point identified, but explanation very unclear. correct as report of explanation not fully clear. Major errors in report of chosen aspect of Minor errors in report of authors' meaning. Relies authors' meaning. Chosen Understanding article. Explains on quotations or chosen point; goes point paraphrased in superficial paraphrase; of article beyond merely student's own words, but little evidence of paraphrasing or very close to original. understanding. Major quoting. Class Minor misunderstandings problems from not knowledge used related to class knowledge. applying class knowledge. correctly where appropriate. Goes beyond Shows understanding of summary; includes relevant issues, but Critical discussion critique, connects to contributes no substantial missing, or shows serious other data or ideas. Active and original points. Focus is misunderstanding of Tight focus on main critical somewhat loose. Some article. No clear focus. point. Report is well organization, but Structure of discussion has thinking; organized; paragraphs argumentation and overall discussion relationships between ideas no clear organization. not always clear. Crucial Examples used, but not is focused, coherent. examples, data not always connected to discussion. Examples, data used given. appropriately. Clear articulate writing Edits needed. Proof reading used. One or two Turns in something. Not will help you. Read aloud minor edits needed to college level work at all. to yourself and or ask Writing be a perfect paper! Get help at the writing others to read it out loud to Keep up the great center. you. work Articulates your thoughts on the article Brief mention of thoughts, Does not write any of your in a clear manner. but did not elaborate. No own thoughts or ideas Your Thoughts Discusses what you mention of learning from about what is discussed in learned from reading reading the article. the article. the article or ideas you might use in the future. Your Score The Journal of Emergency Medicine, Vol. 51, No. 1, pp. 1–8, 2016 ! 2016 Elsevier Inc. All rights reserved. 0736-4679/$ - see front matter Original Contributions COMPARISON OF THE QRS COMPLEX, ST-SEGMENT, AND T-WAVE AMONG PATIENTS WITH LEFT BUNDLE BRANCH BLOCK WITH AND WITHOUT ACUTE MYOCARDIAL INFARCTION Kenneth W. Dodd, MD,*† Kendra D. Elm, BS,*‡ and Stephen W. Smith, MD*‡ *Department of Emergency Medicine, Hennepin County Medical Center, Minneapolis, Minnesota, †Department of Internal Medicine, Hennepin County Medical Center, Minneapolis, Minnesota, and ‡Department of Emergency Medicine, University of Minnesota Medical School, Minneapolis, Minnesota Reprint Address: Kenneth W. Dodd, MD, Department of Emergency Medicine, Hennepin County Medical Center, 701 Park Avenue, Minneapolis, MN 55415 , Abstract—Background: The modified Sgarbossa criteria have been validated as a rule for diagnosis of acute coronary occlusion (ACO) in left bundle branch block (LBBB). However, no analysis has been done on differences in the QRS complex, T-wave, or ST-segment concordance of < 1 mm in the derivation or validation studies. Furthermore, there was no comparison of patients with acute myocardial infarction (AMI) but without ACO (i.e., non–ST-elevation myocardial infarction [non-STEMI]) to patients with ACO or without AMI (no MI). Objective: We compare findings involving the QRS amplitude, ST-segment morphology, ST-concordance < 1 mm, and T-waves in patients with LBBB with ACO, non-STEMI, and no MI. Methods: Retrospectively, emergency department patients were identified with LBBB and ischemic symptoms but no MI, with angiographically proven ACO, and with non-STEMI. Results: ACO, non-STEMI, and no MI groups consisted of 33, 24, and 105 patients. The sum of the maximum deflection of the QRS amplitude across all leads (SQRS) was smaller in patients with ACO than those without ACO (101.5 mm vs. 132.5 mm; p < 0.0001) and a cutoff of SQRS < 90 mm was 92% specific. For ACO, non-concave ST-segment morphology was 91% specific, any ST concordance $ 1 mm was 95% specific, and any ST concordance $ 0.5 mm was 94% sensitive. For non-STEMI, terminal T-wave concordance, analogous to biphasic T-waves, was moderately sensitive at 79%. Conclusions: We found differences in QRS amplitude, ST-segment morphology, and T-waves between patients with LBBB and ACO, nonSTEMI, and no MI. However, none of these criteria outperformed the modified Sgarbossa criteria for diagnosis of ACO in LBBB. ! 2016 Elsevier Inc. All rights reserved. , Keywords—left bundle branch block; acute myocardial infarction; QRS complex; ST-segment; T-wave INTRODUCTION The electrocardiogram (ECG) remains the fastest tool for early diagnosis of acute myocardial infarction (AMI). Historically, the belief that left bundle branch block (LBBB) hopelessly obscures the diagnosis of AMI by ECG has impeded work on this topic. The confusion has come because, at baseline, patients with LBBB exhibit discordance of the QRS complex, ST-segment, and T-wave. That is, patients with LBBB have ST-elevation in leads with negative QRS complexes (Figure 1) and ST-depression, as well as negative Twaves, in leads with positive QRS complexes. When this ‘‘rule of appropriate discordance’’ in LBBB is kept in mind, the diagnosis of acute coronary occlusion (ACO), which is the anatomic substrate for ST-elevation Kenneth W. Dodd and Kendra D. Elm contributed equally to this work. RECEIVED: 15 November 2015; FINAL SUBMISSION RECEIVED: 25 January 2016; ACCEPTED: 3 February 2016 1 2 K. W. Dodd et al. loss of specificity. Third, we hypothesized that nonconcave ST-segment morphology would not be a sensitive or specific marker of ACO, in contrast to previously published guidelines (3). Fourth, we hypothesized that patients with ACO would exhibit hyperacute T-wave equivalents more frequently than non-ACO patients, as manifested by an increased T-wave amplitude (TWA) and discordant TWA/QRS-amplitude ratio (T/QRS). Finally, we hypothesized that patients with non-STEMI and LBBB would more frequently have concordant T-waves, a presumed analogue to T-wave inversions in ECGs with normal conduction. METHODS Study Design and Population Figure 1. Diagram of measurements and morphologies. The main diagram demonstrates normal discordance in left bundle branch block with a negative maximum QRS amplitude (i.e., an S-wave) and resulting positive T-wave, as well as concave STsegment elevation. Appropriate measurements are also demonstrated: S-wave = 19 mm; ST = 1.5 mm; T-wave amplitude (TWA) = 9 mm; ST/S ratio = 1.5/19 = 0.08; discordant T/ QRS ratio (i.e., T/S ratio in this example) = 9/19 = 0.47. Morphologies of straight (A) and convex (B) ST-segments, as well as majority T-wave concordance (C) and terminal T-wave concordance (D) are also shown. myocardial infarction (STEMI), may be made with far more accuracy than previously believed. The modified Sgarbossa criteria were 91% sensitive and 90% specific for diagnosis of ACO in LBBB in the derivation trial (Table 1), and have recently been validated with 80% sensitivity and 99% specificity (1,2). No specific analysis of the QRS complex, ST-segment morphology, concordant ST-deviation of 10 ng/mL (implying probable ACO at the time of ECG). The non-STEMI group consisted of patients who were adjudicated as AMI by a study author (S.W.S) with 24-h troponin-I > 99% upper reference limit (99% upper reference limit range was 0.1–0.6 ng/mL for assays used during the study period) in which ACO was excluded by either angiogram showing no culprit lesion, a lesion but no angiographic occlusion and peak troponin 10 ng/ mL. There were 105 no-MI patients that had negative serial troponin-I for up to 24 h. An additional 24 patients met adjudication criteria for non-STEMI. In total, 162 patients were included in the study. As reported in the original study, there was good inter-rater reliability of the measurements (1). Patient characteristics for each group are shown in Table 2. QRS Amplitude in LBBB and ACO For the sum of QRS amplitudes across all 12 leads (SQRS), the median value was 101.5 mm (IQR 82.5– 115.5 mm) for ACO, 129.75 mm (IQR 103.4–142.3 mm) for non-STEMI, and 132.5 mm (IQR 109.5–159.0 mm) Table 2. Patient Characteristics Characteristic ACO (n = 33) Non-STEMI (n = 24) No MI (n = 105) Age, y (95% CI) Mean no. (%) Peak troponin-I, ng/mL (95% CI) 72.8 (68.4–77.2) 20 (61) 114.7 (65.3–164.1) 70.9 (66.2–75.7) 8 (33) 3.5† (2.34–4.66) 65.5* (61.8–69.2) 50 (48) ACO = acute coronary occlusion; CI = confidence interval; n/a = not applicable; no MI = without acute myocardial infarction; nonSTEMI = non–ST-elevation myocardial infarction. * p < 0.05 compared to ACO. † p < 0.001 compared to ACO. 4 K. W. Dodd et al. Table 3. Criteria for Diagnosis of Acute Coronary Occlusion vs. Non–Acute Coronary Occlusion in Left Bundle Branch Block Criteria QRS amplitude SQRS < 90 mm ST-segment concordance Concordant ST-elevation $ 0.5 mm in any lead Concordant ST-depression $ 0.5 mm in leads V1–V3 Concordant ST-depression $ 0 mm in leads V1–V3 Concordant ST-depression $ 0.5 mm in any lead Concordant ST-depression $ 1.0 mm in any lead Any concordance $ 0.5 mm Any concordance $ 1.0 mm ST-segment morphology Non-concave (convex or straight) ST-segment T-wave to QRS amplitude ratio Discordant T/QRS > 1.25 T-wave concordance Majority T-wave concordance in any lead T-wave concordance in leads V5 or V6 for no MI (p < 0.0001 for both non-STEMI and no MI compared with ACO). When non-ACO patients were compared with ACO patients, the median SQRS was also significantly higher for the non-ACO group (132.5 mm [IQR 108.5–156.5 mm]; p < 0.0001). Using a cutoff value of SQRS 90% specificity for diagnosis of ACO (Table 3). ST-Segment Concordance in LBBB and ACO ST-segment concordance comparisons in LBBB with ACO are found in Table 3. When a cutoff of $0.5 mm of concordant ST-elevation was used in any lead or $0.5 mm of concordant ST-depression in V1–V3, there was no significant difference in sensitivity or specificity when compared with the previously reported cutoffs of $1 mm (p = NS, Tables 1 and 3). A composite rule with combination of any concordance $0.5 mm or ST/ S ratio of # !0.25 yielded 100% (95% CI 87–100) sensitivity and 57% (95% CI 47–65) specificity for the diagnosis of ACO in LBBB. Sensitivity, % (95% CI) Specificity, % (95% CI) 33 (19–52) 92 (85–96) 64 (45–79) 24 (12–43) 39 (23–56) 70 (67–82) 61 (42–77) 94 (78–99) 73 (54–86) 92 (86–96) 99 (95–100) 85 (78–91) 75 (51–84) 95 (95–100) 70 (61–77) 95 (88–97) 55 (37–71) 91 (84–96) 45 (28–63) 93 (87–97) 76 (57–88) 49 (31–66) 62 (53–70) 79 (69–84) p < 0.05). Using a cutoff of discordant T/QRS $1.25 yielded >90% specificity for ACO (Table 3). But this statistical difference in discordant T/QRS is entirely due to the difference in QRS amplitudes. T-Wave Concordance in LBBB In non-STEMI compared with no MI, terminal T-wave concordance of >0.5 mm in any lead was the most sensitive of all criteria analyzed (Table 4). This criterion, as well as majority T-wave concordance in any lead and majority T-wave concordance in leads V5 or V6, was more sensitive for diagnosis of non-STEMI than the modified Sgarbossa criteria (p < 0.05 for all). As expected, majority T-wave concordance in any lead was less specific for ACO than the modified Sgarbossa criteria (p < 0.05, Table 3). T-wave concordance in V5 or V6 was less sensitive and less specific for ACO than the modified Sgarbossa criteria (p = NS). For diagnosis of any MI (i.e., ACO and non-STEMI) compared to no MI, the addition of terminal T-wave concordance to the modified Sgarbossa criteria resulted ST-Segment Morphology in LBBB and ACO Non-concave ST-segment morphology in at least one lead with ST-elevation $1 mm was present in 18 (55%) patients with ACO compared with 11 (9%) non-ACO patients (p < 0.05) resulting in >90% specificity (Table 3). Table 4. Criteria for Diagnosis of Non–ST-Elevation Myocardial Infarction vs. No Acute Myocardial Infarction in Left Bundle Branch Block T-Wave Amplitude and T-Wave Ratios in LBBB and ACO Modified Sgarbossa criteria Terminal T-wave concordance in any lead Majority T-wave concordance in any lead Majority T-wave concordance in leads V5 or V6 The maximum TWA was similar for the ACO (9 mm [IQR 6.5–11 mm]) and non-ACO groups (8 mm [IQR 6.5–11 mm]; p = NS). The median discordant T/QRS ratio was significantly larger for ACO (1.08 [IQR 0.8–1.5]) compared with non-ACO (0.70 [IQR 0.43–0.75]; Criteria Sensitivity, % Specificity, % (95% CI) (95% CI) 8 (2–29) 79* (57–92) 88 (79–93) 47* (37–57) 46* (26–67) 64* (54–73) 29* (13–51) 79* (70–86) * p < 0.05 compared to the modified Sgarbossa criteria. Diagnosis of Acute Myocardial Infarction in Left Bundle Branch Block Table 5. Rules for Diagnosis of Any Acute Myocardial Infarction vs. No Acute Myocardial Infarction in Left Bundle Branch Block Rules Modified Sgarbossa criteria Modified Sgarbossa criteria or majority T-wave concordance in any lead Modified Sgarbossa criteria or terminal T-wave concordance in any lead Sensitivity, % (95% CI) Specificity, % (95% CI) 54 (41–68) 79* (66–88) 88 (79–93) 56* (46–66) 91* (80–97) 43* (33–53) 5 reported that $1 mm concordant ST-elevation in at least one lead and $1 mm concordant ST-depression in leads V1–V3 has high specificity for ACO with relatively low sensitivity. In this study, we found that lowering the cutoff to $ 0.5 mm of concordant ST-elevation or ST-depression increased the sensitivity of these criteria, while retaining a relatively high specificity with each criterion analyzed independently. When a composite rule consisting of any concordance (ST-elevation or ST-depression) $ 0.5 mm or an ST/S ratio # !0.25 was analyzed, the sensitivity was 100% but the specificity did decrease significantly. * p < 0.05 compared to the modified Sgarbossa criteria. ST-Segment Morphology in LBBB and ACO in >90% sensitivity (p < 0.05), but at the expense of specificity. Addition of majority T-wave concordance also significantly increases sensitivity, but to a lesser extent (Table 5). DISCUSSION Salient Findings We analyze several QRS, ST-segment, and T-wave characteristics in patients with LBBB and angiographically defined ACO, LBBB, and non-STEMI, and LBBB without AMI. We found that the SQRS voltage was significantly lower in patients with ACO compared to non-ACO controls. With regard to ST-segment changes, we found that any ST concordance $1 mm was 95% specific for ACO, while a cutoff of $0.5 mm was 94% sensitive for ACO. We also found that non-concave STsegment morphology was 91% specific for ACO, but had poor sensitivity. For non-STEMI, terminal T-wave concordance had relatively high sensitivity compared to the other criteria studied, but this was not sufficient to add utility to the diagnosis. QRS Amplitude in LBBB and ACO Comparatively low amplitude of the QRS complex has been found to correlate with areas of ST-segment elevation and eventual myocardial loss in patients with normal cardiac conduction (7,8). In a study of 143 patients with normal conduction and ‘‘subtle’’ anterior ACO compared to 171 patients with early repolarization, R-wave amplitude in V2–V4 was lower in patients with subtle anterior ACO than those with early repolarization (9). In LBBB, we found that patients with ACO had lower QRS voltage on the ECG compared to non-ACO patients. ST-Segment Concordance in LBBB and ACO ST-segment concordance $1 mm has been well-studied in LBBB and AMI (1,2,10). We have previously Wang et al. asserted that upward convexity is the key to diagnosing ACO in LBBB (3). Analysis of ST-segment morphology in 171 patients with normal conduction (56 with AMI) presenting with ST-elevation and symptoms of acute coronary syndrome done by Brady et al. reported that upwardly non-concave ST-segment morphology had 97% sensitivity and 77% specificity for AMI in any coronary territory (6). Importantly, Brady et al. used creatine kinase-MB (CK-MB) for diagnosis of AMI and thus included both STEMI and non-STEMI patients. Kosuge et al. studied 77 consecutive patients with proven left anterior descending coronary artery (LAD) occlusion and found that 53 (69%) had non-concave morphology (41 with straight and 12 with convex) and 24 (31%) had concave morphology (11). Our study found similar results for utility of non-concave morphology to diagnose ACO in LBBB, with sensitivity of 55% and specificity of 91%. However, in the diagnosis of ACO in LBBB, the modified Sgarbossa criteria were far more sensitive than morphology analysis without loss of specificity. T-Waves in LBBB and ACO In the largest study on hyperacute T-waves in normal conduction, Collins et al. screened 13,393 adult ECGs for abnormally large TWA and then excluded patients with other causes of large TWA (e.g., BBB, hyperkalemia, acute hypertension, acute central nervous system events, valvular heart disease, and ventricular hypertrophy) (12). Interestingly, LBBB was the most common reason patients were classified as having a primary cause of high TWA. Patients with ‘‘clinically verifiable’’ AMI, as determined by the treating physician, were classified as having hyperacute T-waves, while other patients were called early repolarization variants. The study identified a combination of four criteria that characterize hyperacute T-waves with 90% specificity and 62% sensitivity: T/ QRS >0.75, ST/T >0.25, STE >3 mm, and age older than 45 years. In another study, Smith et al. compared ECGs with normal conduction and proven LAD 6 occlusion to those with early repolarization and found no significant difference in TWA in leads V2–V4, although the T/QRS ratio was higher in LAD occlusion (9). Indeed, in this study, we found that patients with ACO had no difference in TWA, but they did have a higher median discordant T/QRS ratio than both non-STEMI and no MI groups; a discordant T/QRS >1.25 yielded >90% specificity for ACO. Thus, the T/QRS differences are the result of decreases in the QRS amplitude in patients with LBBB and ACO. T-Waves in LBBB and Non-STEMI Jacobsen et al. performed a retrospective analysis of Twave findings in 468 patients with non-STEMI or unstable angina with normal conduction (13,14). They reported biphasic T-waves, T-waves with abnormal axis (e.g., inverted T-waves), and T-waves with amplitude outside the normal range were associated with adverse outcomes at 30 days and 1 year (13,14). In Jacobsen et al.’s 2001 study, 62% of patients with ST-depression and 35% of patients without ST-depression were found to have biphasic T-waves. A study by Hyde et al. found 16% of 353 patients with normal conduction and acute coronary syndrome (including STEMI, non-STEMI, and unstable angina) had T-wave inversion (15). In this study of LBBB patients, we found a higher rate of terminal T-wave concordance (sensitivity 79%) than majority T-wave concordance (sensitivity 46%) among nonSTEMI patients; these measures may be analogous to biphasic T-waves and T-wave inversions, respectively. Diagnosis of Any MI in LBBB As expected, both the modified Sgarbossa criteria and the original Sgarbossa criteria (data not shown) have poor sensitivity for any MI. This is because the modified Sgarbossa criteria were derived from a population of patients with ACO and non-STEMI patients were included in the control group. The original Sgarbossa criteria were derived among patients with any MI diagnosed by CKMB, yet these still had poor sensitivity for any MI in the original study and had only 20% sensitivity in a systematic review (16). However, in Sgarbossa’s original study, positive T-waves in leads V5 and V6 (i.e., concordant T-waves in V5 and V6) had 92% specificity for any MI. When terminal T-wave concordance, our most sensitive criterion for non-STEMI, was added to the modified Sgarbossa criteria for the diagnosis of any MI, the sensitivity increased significantly (91%); however, this was at the expense of a much lower specificity (43%). Overall, none of the criteria we studied for the diagnosis of any MI in LBBB are useful clinically because the prevalence of AMI (both STEMI and non-STEMI) K. W. Dodd et al. in unselected LBBB patients presenting to the ED is only around 7% (17). With such a low prevalence, high specificity is vital to avoid a very low positive predictive value. Limitations Limitations of our study include a retrospective design with relatively small sample size of arterial occlusions, which decreases the ability to detect meaningful differences among subgroups. Our sample size is limited primarily by the fact that AMI is rare in patients presenting to the emergency department with LBBB and symptoms suggestive of myocardial ischemia (17). However, with the exception of the validation of the modified Sgarbossa criteria (n = 45 ACO), this study is the largest of its kind on an unselected cohort of proven coronary occlusion in the presence of LBBB. Overall, a larger multivariate analysis of these criteria, and combinations thereof, is needed. This will require data from either a larger multicenter retrospective trial or, ideally, a very large prospective trial with baseline clinical characteristics of patients as well as angiographic, echocardiographic, and other clinical outcomes data. If clinically useful criteria are identified, they should need to be incorporated into automated ECG algorithms so that clinicians do not have to remember and make complex measurements. CONCLUSIONS Our study found that patients with LBBB and AMI do have QRS amplitude, ST-segment morphology, and Twave differences that are analogous to patients with normal conduction. While several criteria were quite specific or sensitive for the diagnosis of ACO in LBBB, none, either alone or in combination, outperformed the modified Sgarbossa criteria, which remain superior to other ECG criteria in the diagnosis of ACO in LBBB. REFERENCES 1. Smith SW, Dodd KW, Henry TD, et al. Diagnosis of ST-elevation myocardial infarction in the presence of left bundle branch block with the ST-elevation to S-wave ratio in a modified Sgarbossa rule. Ann Emerg Med 2012;60:766–76. 2. Meyers HP, Limkakeng AT Jr, Jaffa EJ, et al. Validation of the modified Sgarbossa criteria for acute coronary occlusion in the setting of left bundle branch block: a retrospective case-control study. Am Heart J 2015;170:1255–64. 3. Wang K, Asinger RW, Marriott HJL. ST-segment elevation in conditions other than acute myocardial infarction. N Engl J Med 2003; 349:2128–35. 4. Surawicz B, Childers R, Deal BJ, Gettes LS. AHA/ACCF/HRS recommendations for the Standardization and interpretation of the electrocardiogram. Part III: intraventricular conduction disturbances. J Am Coll Cardiol 2009;53:976–81. Diagnosis of Acute Myocardial Infarction in Left Bundle Branch Block 5. Smith SW. Upwardly concave ST segment morphology is common in acute left anterior descending coronary occlusion. J Emerg Med 2006;31:69–77. 6. Brady WJ, Syverud SA, Beagle C, et al. Electrocardiographic STsegment elevation: the diagnosis of acute myocardial infarction by morphologic analysis of the ST segment. Acad Emerg Med 2001;8:961–7. 7. Salerno DM, Asinger RW, Elsperger J, et al. Increasing precordial QRS voltage correlates with improvement in left ventricular function following anterior myocardial infarction. J Electrocardiol 1988;21:303–12. 8. Kilpatrick D, Bell AJ. The relationship of ST elevation to eventual QRS loss in acute inferior myocardial infarction. J Electrocardiol 1989;22:343–8. 9. Smith SW, Khalil A, Henry TD, et al. Electrocardiographic differentiation of early repolarization from subtle anterior STSegment elevation myocardial infarction. Ann Emerg Med 2012;60:45–56. 10. Sgarbossa EB, Pinski SL, Barbagelata A, et al. Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle-branch block. GUSTO-1 (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries) Investigators. N Engl J Med 1996;334:481–7. 7 11. Kosuge M, Kimura K, Ishikawa T, et al. Value of ST-segment elevation pattern in predicting infarct size and left ventricular function at discharge in patients with reperfused acute anterior myocardial infarction. Am Heart J 1999;137:522–7. 12. Collins MS, Carter JE, Dougherty JM, et al. Hyperacute T-wave criteria using computer ECG analysis. Ann Emerg Med 1990;19: 114–20. 13. Jacobsen MD, Wagner GS, Holmvang L, et al. Clinical significance of abnormal T-waves in patients with non-ST-Segment elevation acute coronary syndromes. Am J Cardiol 2001;88:1225–9. 14. Jacobsen MD, Wagner GS, Holmvang L, et al. Quantitative T-wave analysis predicts 1 year prognosis and benefit from early invasive treatment in the frisc ii study population. Eur Heart J 2005;26: 112–8. 15. Hyde TA, French JK, Wong C, et al. Four-year survival of patients with ST-segment elevation and prognostic significance of 0.5-mm ST-segment depression. Am J Cardiol 1999;84:379–85. 16. Tabas JA, Rodriguez RM, Seligman HK, et al. Electrocardiographic criteria for detecting acute myocardial infarction in patients with left bundle branch block: a meta-analysis. Ann Emerg Med 2008; 52:329–36. 17. Chang AM, Shofer FS, Tabas JA, et al. Lack of association between left bundle-branch block and acute myocardial infarction in symptomatic ED patients. Am J Emerg Med 2009;27:916–21.
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The electrocardiogram (ECG) is one of the effective instruments for early diagnosis of
acute myocardial infection (AMI). Conventionally, the thought that left bundle branch block
(LBBB) fails to prevent the diagnosis of AMI has obstructed assessment of this study. The issue
has arisen because patients with LBBB display dissonance of the QRS complex, T-wave, and
ST-segment. In other words, patients with LBBB have ST-elevation in leads with negative QRS
multiplexes and ST-depression. Therefore, patients with LBBB and AMI have ST-segment
morphology, QRS amplitud...

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