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Posterior myocardial infarction: Are we failing to diagnose this?
Abstract and Figures
Isolated posterior ST-elevation myocardial infarction (STEMI) accounts for up to 7% of STEMIs. The diagnosis is suggested by indirect anterior-lead ECG changes. Confirmation requires presence of ST-elevation in posterior-leads (V7-V9). We investigated the ability of hospital doctors and paramedics to diagnose posterior STEMI (PMI).
Doctors in the emergency department and acute medical unit at two teaching hospitals and West Midlands Ambulance Service Paramedics were asked to interpret a 12-lead ECG illustrating ST-depression and dominant R-wave in V1-V2 in the context of cardiac chest pain, and identify PMI as a potential diagnosis. Their ability to identify PMI was compared with their ability to diagnose anterolateral STEMI on a 12-lead ECG. We assessed whether doctors knew that posterior-leads were required to confirm PMI and whether doctors and nurses could position posterior-leads.
44 of the 117 doctors (38%) identified PMI as a potential diagnosis. PMI was identified by 73% of registrars, 30% of senior house-officers and 18% of house-officers. 50% of doctors who identified potential PMI knew that posterior-leads were required to confirm the diagnosis. 20% of doctors correctly positioned these and 19% knew the diagnostic criteria for PMI (ST-elevation ≥1 mm in V7-V9). 13 of the 60 nurses (22%) in the emergency department and acute medical unit correctly positioned posterior-leads. Five of the 50 (10%) paramedics identified PMI as a potential diagnosis. Doctors and paramedics were significantly better at diagnosing anterolateral STEMI than PMI.
A significant proportion of doctors and paramedics were unable to diagnose PMI. Hence, the majority of PMIs may be being missed. Routine use of posterior-leads in the standard assessment of patients with chest pain may identify up to an additional 7% of STEMIs, allowing prompt reperfusion therapy, which would reduce morbidity and mortality.
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... This low sensitivity occurs for a number of reasons including: 1) the dynamic nature of UA/NSTEMI in which blood ow can spontaneously return or be supplied through a collateral artery; 2) the limited 10-second duration of the standard ECG; and, 3) the lack of leads especially in the posterior wall of the myocardium making it di cult to detect ischemia [2,13]. Though AHA/ACC guidelines consider it reasonable to place leads over the posterior wall (V7-V9), it is not necessarily performed in clinical practice [2,14]. Lastly, the ECG is often misinterpreted by providers further leading to treatment delays [14,15]. ...
... Though AHA/ACC guidelines consider it reasonable to place leads over the posterior wall (V7-V9), it is not necessarily performed in clinical practice [2,14]. Lastly, the ECG is often misinterpreted by providers further leading to treatment delays [14,15]. Newer research has identi ed novel characteristics on the ECG related to UA/NSTEMI which have higher sensitivity and the potential to overcome these identi ed limitations [12,16]. ...
... Some characteristics of the ECG have a low sensitivity for a true infarction because the standard 10-second ECG is simply a snapshot of a very dynamic process [12,13,16]. Furthermore, the standard 12-lead ECG does not have posterior leads and can be easily misinterpreted [14,15]. Novel characteristics such as QRS-T angle on the 12-lead ECG have improved sensitivity and can overcome some of these other limitations [16]. ...
Background
The incidence of unstable angina/ non-ST elevation MI (UA/NSTEMI) continues to rise, and despite treatment advancements the risks of death and re-infarction persist. The electrocardiogram (ECG) remains the first assessment of myocardial ischemia caused by UA/NSTEMI, and is performed within the first 10-minutes of emergency presentation. Once ischemia is identified on the ECG, interventions are delivered timely to decrease the risk of death and re-infarction. Since the ECG informs intervention decisions, it is crucial providers understand the prognostic value of individual characteristics on the ECG. However, characteristics on ECG are limited due to low sensitivity though newer research has aimed to overcome these limitations. This is the protocol for a systematic review and meta-analysis that will assess the significance of individual characteristics on the ECG for predicting death and re-infarction among UA/NSTEMI patients, and identify remaining gaps in clinical understanding of ECG.
Methods
This is the protocol for a systematic review and meta-analysis that will be conducted to assess the prognostic value of specific characteristics on the ECG in the emergency department for predicting re-infarction and death. Electronic databases and specific journals will be searched using predefined search terms to identify relevant studies. Eligible studies will include peer-reviewed research articles with empirical findings on the risk of re-infarction and death based on individual characteristics on the ECG. To be inclusive, we will assess characteristics on both the 12-lead and 15-lead ECG. Methodological quality of will be assessed with the Newcastle-Ottawa Quality Assessment Scale and GRADE criteria. A random effects meta-analysis and exploratory meta-regression will be conducted. Citations will be managed using EndNote X9. Meta-Essentials package for Microsoft Excel and STATA will be used to compute statistics.
Discussion
This study will systematically evaluate and quantitatively assess the evidence available on the prognostic value of individual characteristics on the ECG for the risk of death and re-infarction among UA/NSTEMI patients. By conducting this study, we will inform clinicians about the significance of characteristics on the ECG to better inform treatment decisions for UA/NSTEMI patients.
Registration
This systematic review and meta-analysis is registered with the International Prospective Register of Systematic Reviews (PROSPERO; ID CRD42020158491).
... [5] Importantly, the isolated APMI represents a STEMI equivalent, as defined by the ACC in their Expert Consensus Pathway; thus, the recognition of the electrocardiographic presentation of isolated APMI is necessary in that it potentially allows for urgent management, including reperfusion therapy. [2] Unfortunately, clinicians not infrequently fail to recognize the electrocardiographic features of isolated APMI and thus manage the patient as if a larger AMI is not occurring; this failure to recognize APMI results in longer times to urgent reperfusion therapy as compared to patients with inferior, lateral, or anterior STEMI [7,8] and related adverse outcomes. ...
... If needed, additional electrocardiographic leads (i.e., beyond the 12-lead ECG) can be used to directly image the posterior wall of the left ventricle; these posterior leads are termed leads V7, V8, and V9; current diagnostic criteria are ST-segment elevation >0.05 mV in one or more posterior leads or >0.10 mV for younger men <40 years old. [7] As noted, these patients with isolated APMI are potential candidates for urgent reperfusion therapy with either fibrinolysis or PCI. The clinician should consider APMI among those ACS patients with precordial ST-segment depression, particularly those individuals who demonstrate horizontal ST-segment depression, prominent positive QRS complexes in leads V1 and/or V2, and upright T-waves in leads V1 to V3 and/or V4. [2] Hyperacute T-Wave ...
This review considers high-risk electrocardiographic patterns in the acute coronary syndrome (ACS) patient; we review 7 electrocardiogram presentations lacking diagnostic criteria for ST-segment elevation myocardial infarction (STEMI) yet likely representing either STEMI equivalent syndromes or ACS presentations with significant short-and long-term risk. The STEMI equivalent presentations include acute posterior wall myocardial infarction, the hyperacute T-wave of early STEMI, de Winter syndrome, first diagonal of the left anterior descending artery occlusion, and left bundle branch block modified Sgarbossa positive findings. High-risk presentation, not felt to be STEMI equivalent entities yet still possessing significant risk of short-and long-term adverse outcome, include lead aVR ST-segment elevation and Wellens syndrome. The features of each presentation, highlighting the electrocardiographic abnormalities, are presented and discussed.
... PMIs are often missed, likely due to the relatively low incidence of isolated PMIs, as well as clinicians mistaking infarction for ischemia and failing to confirm the diagnosis with a posterior lead ECG. In a study conducted by Khan, Chauhan, Mozdiak, Khan, and Varma (2012), only 38% of doctors and 10% of paramedics were able to identify a PMI as a potential diagnosis. Of those 38% of doctors, only 50% knew a posterior lead ECG was necessary to confirm the diagnosis. ...
... Of those 38% of doctors, only 50% knew a posterior lead ECG was necessary to confirm the diagnosis. Isolated PMIs are relatively rare (3%-11% of acute myocardial infarctions [AMIs]) compared with other areas of infarction (Brady et al., 2001), and posterior leads are not routinely used in a patient presenting with potential STEMI (Khan et al., 2012). These two factors lead to a lack of training and education on detecting a PMI in a clinical setting. ...
Health care professionals and hospitals have made tremendous advances in detecting, diagnosing, and treating posterior myocardial infarction over many decades. Electrocardiogram (ECG) alone is used to make a timely diagnosis of ST-segment elevation myocardial infarction in the emergency department. The typical signs of myocardial infarction, left-sided chest discomfort with radiation to the jaw or left arm, rule out a wide range of patient presentations with ST-segment elevation myocardial infarction. This variation in clinical symptoms is exacerbated by the fact that most ECG monitors lack algorithms that account for posterior myocardial infarction interpretation. Therefore, health care practitioners must exercise caution when dismissing nondiagnostic and faint ECG abnormalities as normal or unimportant.
... [17][18][19][20] On the process, sensitivity of detecting PMI was increased after adjusting cut off value for ST elevation in posterior leads. [42] However in many studies, it has been observed that,posterior leads are not recorded routinely in most of the health centres.ED staff even in cardiac centres do not record posterior leads either due to cumbersome procedure or lacks the knowledge to do so in PMI . [43] Only around 10% cardiologists and emergency physicians routinely practice posterior leads. ...
... Around 12% patient of PMI with anterior lead presentation does not show significant (≥ 1mm)ST elevation in posterior leads. [48]The sensitivity of detecting PMI from posterior lead increases from 49% to 94% , only when ischemic ST threshold adjusted from 1 to 0.5 mm, [42] which is close to upper normal value. [49] Therefore if diagnosis of PMI is obvious from the ECG findings in the anterior leads meeting ST depression criteria of guidelines, then recording of the posterior leads can be falsely reassuring. ...
Introduction:Patients with isolated PMI is most often misdiagnosed as anterior subendocardial ischemia and get deprived of emergent reperfusion therapy. Therefore patients with PMI often presents with dreadful complications like acute ischemic MR,LVF,leading to higher mortality equivalent to anterior wall MI despite normal or borderline EF. Therefore a qualitative analytic study was conducted after collecting and compiling related literatures and guidelines to derive a conclusion about early and accurate diagnosis of isolated PMI. During analysis we obtained useful information as described below. Prominent R wave in V1-V2 takes averagely 33 hours to develop after onset of symptom, therefore it is unobserved in early golden hour of PMI. However it was included as a sign of acute myocardial ischemia in a recent guideline.As precordial ST depression is the one and only important electrocardiographic signs in early golden hours of PMI,therefore above ECG changes most often misdiagnosed as anterior subendocardial ischemia. Most of the important guidelines considers only isolated pattern ST depression (≥ 0.5 mm) as isolated posterior wall MI. Whereas diffuse pattern(v1-v6) is the common pattern in isolated PMI, therefore such pattern most often misdiagnosed as subendocardial ischemia. As ST depression in V2,V3 is a specific marker of PMI, therefore diffuse patterns with maximal ST depression in V2,V3 may be considered as a criteria for PMI .Guidelines suggests recording of posterior leads in patients with ACS with ST depression (≥0.5 mm) or non-diagnostic ECG changes in right anterior precordial leads in an attempt to fit PMI into ST elevation criteria of STEMI paradigm , whereas the same was not practiced most often by training or resident physicians due to lack of knowledge and awareness. However recent OMI paradigm,which is superior to STEMI paradigm in terms of accuracy,does not strictly considers ST elevation criteria for emergent reperfusion therapy, when ECG entity firmly concludes acute coronary occlusion. Conclusion: Presence of R wave in V1,V2 is a late evolved electrocardiographic sign of PMI and it doesn't warrants emergent reperfusion therapy.Isolated (v1-v3) or diffuse (v1-v6) pattern with maximal ST depression (≥0.5 mm) in V2,V3 is a specific electrocardiographic sign of acute or hyper-acute posterior wall MI and seeks emergent reperfusion therapy. Whereas non diagnostic ECG like minuscule ST depression (< 0.5 mm) in anterior precordial leads can represent isolated posterior wall MI and may require further confirmation by screening echocardiography or recording posterior leads. Keywords: Isolated posterior wall MI, R wave in v1,v2,ST depression in v2,v3,posterior leads
... We also correlated the results of the ECG interpretation made by triage nurses with acute cardiovascular events, showing a sensitivity of 84.6% and a specificity of 87.0% in identifying electrocardiographic changes attributable to rapidly deteriorating clinical conditions. Unlike other studies relying on questionnaires or charts in simulated scenarios (Coll-Badell et al., 2017;Khan et al., 2012;Kim & Kim, 2020;Rahimpour et al., 2021), ...
Aims
The prompt recording of the electrocardiogram (ECG) and its correct interpretation is crucial to the management of patients who present to the emergency department (ED) with cardiovascular symptoms. Since triage nurses represent the first healthcare professionals evaluating the patient, improving their ability in interpreting the ECG could have a positive impact on clinical management. This real‐world study investigates whether triage nurses can accurately interpret the ECG in patients presenting with cardiovascular symptoms.
Design
Prospective, single‐centre observational study conducted in a general ED of General Hospital of Merano in Italy.
Methods
For all patients included, the triage nurses and the emergency physicians were asked to independently interpret and classify the ECGs answering to dichotomous questions. We correlated the interpretation of the ECG made by the triage nurses with the occurrence of acute cardiovascular events. The inter‐rater agreement in ECG interpretation between physicians and triage nurses was evaluated with Cohen's kappa analysis.
Results
Four hundred and ninety‐one patients were included. The inter‐rater agreement between triage nurses and physicians in classifying an ECG as abnormal was good. Patients who developed an acute cardiovascular event were 10.6% (52/491), and in 84.6% (44/52) of them, the nurse accurately classified the ECG as abnormal, with a sensitivity of 84.6% and a specificity of 43.5%.
Conclusion
Triage nurses have a moderate ability in identifying alterations in specific components of the ECG but a good ability in identifying patterns indicative of time‐dependent conditions correlated with major acute cardiovascular events.
Impact for Nursing
Triage nurses can accurately interpret the ECG in the ED to identify patients at high risk of acute cardiovascular events.
Reporting Method
The study was reported according to the STROBE guidelines.
No Patient or Public Contribution
The study did not involve any patients during its conduction.
... It has been reported that there is a lack of ECG interpretation skill among primary contacts or resident physicians to detect PMI from anterior precordial leads. A major proportion (approximately 80%) of resident doctors, health workers, and paramedics don't have an idea about the correct positioning of nonconventional posterior leads and the diagnosis of PMI based on ST elevation criteria in posterior leads (35). Emergency staff, even in cardiac centres, does not record posterior leads due to a lack of knowledge to do so (36). ...
Posterior wall MI (PMI) is known for it's electrocardiographically silent (mimicking NSTACS) and clinically malignant manifestations like LVF, cardiogenic shock, death, etc. Emergent reperfusion therapy can change outcomes in favour of patients. The most common modality of emergent reperfusion therapy in India is thrombolytic therapy. Because thrombolytic therapy is beneficial in PMI patients but not beneficial, and may even be harmful, in NSTACS patients, it should only be used after electrocardiographic confirmation of PMI. However, confirmation of PMI and decision-making about the administration of thrombolysis are tough challenges due to limitations both at the guideline and implementation levels. Therefore, a systemic review was conducted, collecting and compiling all the relevant literature to discuss those limitations, arising issues, and possible countermeasures. During analysis, we obtained useful information, as described below. The guideline mentions different possible criteria to suspect PMI from secondary ST depression in conventional right anterior precordial leads and recommends a threshold (close to normal value) criteria to confirm PMI from ST elevation in nonconventional posterior leads. The absence of uniformity among guidelines, reliability of posterior leads, credibility of R wave in V1 and V2, ECG interpretability among physicians, and accessibility of PMI in guideline (for pre-hospital thrombolysis) are the major limitations, which can create tough challenges during the administration of thrombolysis. Patients with acute PMI may miss the opportunity offered by thrombolytic therapy, developing devastating complications. whereas patients with NSTACS or late-developed PMI may get the opportunity for thrombolysis, which is not beneficial but rather harmful. Conclusion: Thrombolytic therapy can't be administered based on either non-uniform, possible ST depression criteria in the right anterior precordial lead or on non-reliable ST elevation criteria in the posterior leads. A uniform, specific criterion to confirm PMI based on electrocardiographic findings in conventional right anterior precordial leads is in deep need. The development of ECG interpretation skills among physicians, health workers, and paramedics to detect PMI can help avoid missed diagnoses during the "golden hour." Inclusion of posterior wall MI in the guidelines for pre-hospital thrombolysis could improve the outcome of patients with PMI.
... Less than 50% of all included studies (n = 20) reported nurses' knowledge of rhythm interpretation. The remaining studies assessed knowledge of continuous monitoring (n = 3) (Blakeman et al., 2015;Pickham et al., 2012;Sangkachand et al., 2011), lead selection and lead placement (n = 6) (Drew et al., 1991;Fålun et al., 2020;Khan et al., 2012;Rajaganeshan et al., 2008;Wirt et al., 2014;Zhou et al., 2012), AMI interpretation (n = 8), and nurses' ability to intervene when faced with rhythm abnormalities (n = 1) (Tai et al., 2012). Nurses' knowledge of rhythm interpretation and their ability to manage arrhythmias was evaluated in three studies (Brooks et al., 2016;Costanzo et al., 2013;Entenmann et al., 2018). ...
Aims
Identify and synthesize evidence of nurses’ competency in electrocardiogram interpretation in acute care settings.
Design
Systematic mixed studies review.
Data sources
Cumulative Index to Nursing and Allied Health Literature, Medline, Scopus and Cochrane were searched in April 2021.
Review methods
Data were selected using the updated Preferred Reporting Items for Systematic Reviews and Meta‑Analysis framework. A data‐based convergent synthesis design using qualitative content analysis was adopted. Quality appraisal was undertaken using validated tools appropriate to study designs of the included papers.
Results
Forty‐three papers were included in this review. Skills and attitudes were not commonly assessed, as most studies referred to ‘competency’ in the context of nurses’ knowledge in electrocardiogram interpretation. Nurses’ knowledge levels in this important nursing role varied notably, which could be partly due to a range of assessment tools being used. Several factors were found to influence nurses’ competency in electrocardiogram interpretation across the included studies from individual, professional and organizational perspectives.
Conclusion
The definition of ‘competency’ was inconsistent, and nurses’ competency in electrocardiogram interpretation varied from low to high. Nurses identified a lack of regular training and insufficient exposure in electrocardiogram interpretation. Hence, regular, standard training and education are recommended. Also, more research is needed to develop a standardized and comprehensive electrocardiogram interpretation tool, thereby allowing educators to safely assess nurses’ competency.
Impact
This review addressed questions related to nurses’ competency in electrocardiogram interpretation. The findings highlight varying competency levels and assessment methods. Nurses reported a lack of knowledge and confidence in interpreting electrocardiograms. There is an urgent need to explore opportunities to promote and maintain nurses’ competency in electrocardiogram interpretation.
... X (l−1) t (n, c) is the t th feature map at (l − 1) th convolution layer. Similarly, the feature maps for second, third and fourth convolution layers are evaluated using equation (7). The X (l) t is denoted as the t th feature map for l th convolution layer. ...
Myocardial infarction (MI) occurs due to the decrease in the blood flow into one part of the heart, and it further causes damage to the heart muscle. The 12-channel electrocardiogram (ECG) has been widely used to detect and localize MI pathology in clinical studies. The vectorcardiogram (VCG) is a 3-channel recording system used to measure the heart’s electrical activity in sagittal, transverse, and frontal planes. The VCG signals have advantages over the 12-channel ECG to localize posterior MI pathology. Detection and localization of MI using VCG signals are vital in clinical practice. This paper proposes a multi-channel multi-scale two-stage deep-learning-based approach to detect and localize MI using VCG signals. In the first stage, the multivariate variational mode decomposition (MVMD) decomposes the three-channel-based VCG signal beat into five components along each channel. The multi-channel multi-scale VCG tensor is formulated using the modes of each channel of VCG data, and it is used as the input to the deep convolutional neural network (CNN) to classify MI and normal sinus rhythm (NSR) classes. In the second stage, the multi-class deep CNN is used for the categorization of anterior MI (AMI), anterior-lateral MI (ALMI), anterior-septal MI (ASMI), inferior MI (IMI), inferior-lateral MI (ILMI), inferior-posterior-lateral (IPLMI) classes using MI detected multi-channel multi-scale VCG instances from the first stage. The proposed approach is developed using the VCG data obtained from a public database. The results reveal that the approach has obtained the accuracy, sensitivity, and specificity values of 99.58%, 99.18%, and 99.87%, respectively, for MI detection. Moreover, for MI localization, we have obtained the overall accuracy value of 99.86% in the second stage for our proposed network. The proposed approach has demonstrated superior classification performance compared to the existing VCG signal-based MI detection and localization techniques.
... Acute total occlusion of the LCx may result in isolated posterior infarction with ST elevation which can be detected in leads V7-V9 only, which are rarely investigated in everyday clinical practice [10,18]. Furthermore, isolated posterior infarction is commonly missed [19] in everyday practice and is associated with longer revascularization times [20] and is less likely to be treated invasively [21]. Conceivably, this group of NSTEMI patients may really represent a subset of STEMI patients that are not diagnosed adequately by the ECG [9]. ...
Based on 12‑lead electrocardiogram (ECG) findings, myocardial infarction (MI) patients are dichotomized to ST-elevation MI (STEMI) and non ST-elevation MI (NSTEMI) in terms of management strategy. NSTEMI patients are increasing in numbers worldwide, among which an approximately 30% are associated with a total occlusion of a coronary artery. This review summarizes recent evidence in epidemiology, clinical, laboratory, ECG and prognostic characteristics of this NSTEMI sub-group. Patients with a diagnosis of NSTEMI and a total occluded coronary artery (TOCA) represent a sub-group of NSTEMI patients with total occlusion of coronary arteries and associated high-risk that are frequently not managed according to a STEMI-like pathway. The present review echoes a call for action in changing our everyday clinical practice. Therefore, we propose a new triage algorithm by which recognition of high-risk features in NSTEMI patients is central in order to identify STEMI ‘equivalents’ among NSTEMI patients in terms of similar pathology and high-risk who may benefit from immediate invasive strategy (<2 h).
... В исследовании J.N.Khan и соавт. 79 из 177 (68 %) врачей не смогли выявить задний ИМ [12]. В более позднем исследовании среднее время «дверь -баллон» было длиннее среди пациентов с задним ИМ, что привело к уменьшению доли коронарной реперфузии в целевое время, увеличению длительности пребывания в стационаре и частоты внутригоспитальных осложнений [13]. ...
Acute coronary syndromes remain a leading cause of preventable early deaths. However, previous studies have indicated that paramedics' compliance with chest pain protocols is suboptimal and that many patients do not receive the benefits of appropriate prehospital treatment.
To evaluate paramedics' level of compliance with national clinical practice guidelines and to investigate why, in certain circumstances, they may deviate from the clinical guidelines.
The Health Service Executive Mid-Western Regional Ambulance Service which serves a mixed urban and rural population across three counties in the west of Ireland.
A retrospective review of completed ambulance Patient Care Report Forms was conducted for all adult patients with non-traumatic chest pain treated between 1 December 2007 and 31 March 2008. During the same study period, paramedics were asked to complete a prospective questionnaire survey investigating the rationale behind their treatment decisions, their estimation of patient risk and their attitudes towards the clinical practice guidelines and training.
382 completed Patient Care Report Forms were identified for patients with chest pain, of whom 84.8% received ECG monitoring, 75.9% were given oxygen, 44.8% were treated with sublingual glyceryl trinitrate (GTN) and 50.8% were treated with aspirin. Only 20.4% of patients had a prehospital 12-lead ECG recorded. 58 completed questionnaires were returned (response rate 15%); 64% of respondents said they had received insufficient training to identify ECG abnormalities.
Prehospital treatment with oxygen, aspirin, sublingual GTN and ECG monitoring remains underused by paramedics, even though only a small number of patients had documented contraindications to their use. The small number of patients who received a prehospital 12-lead ECG is a cause of particular concern and suggests that incomplete patient assessment may contribute to undertreatment. Further provision of training and equipment is necessary to enable paramedics to more accurately assess and treat patients with acute coronary syndromes.
Objectives:
This study was done to determine whether electrocardiographic (ECG) isolated ST-segment elevation (ST) in posterior chest leads can establish the diagnosis of acute posterior infarction in patients with ischemic chest pain and to describe the clinical and echocardiographic characteristics of these patients.
Background:
The absence of ST on the standard 12-lead ECG in many patients with acute posterior infarction hampers the early diagnosis of these infarcts and thus may result in inadequate triage and treatment. Although 4% of all acute myocardial infarction (AMI) patients reveal the presence of isolated ST in posterior chest leads, the significance of this finding has not yet been determined.
Methods:
We studied 33 consecutive patients with ischemic chest pain suggestive of AMI without ST in the standard ECG who had isolated ST in posterior chest leads V7 through V9. All patients had echocardiographic imaging within 48 h of admission, and 20 patients underwent coronary angiography.
Results:
Acute myocardial infarction was confirmed enzymatically in all patients and on discharge ECG pathologic Q-waves appeared in leads V7 through V9 in 75% of the patients. On echocardiography, posterior wall-motion abnormality was visible in 97% of the patients, and 69% had evidence of mitral regurgitation (MR), which was moderate or severe in one-third of the patients. Four patients (12%), all with significant MR, had heart failure, and one died from free-wall rupture. The circumflex coronary artery was the infarct related artery in all catheterized patients.
Conclusions:
Isolated ST in leads V7 through V9 identify patients with acute posterior wall myocardial infarction. Early identification of those patients is important for adequate triage and treatment of patients with ischemic chest pain without ST on standard 12-lead ECG.
Objectives:
This study was designed to investigate the association between wall motion abnormalities and the occurrence of ischemic mitral regurgitation in patients with a first inferior or posterior myocardial infarction and to reassess the role of thrombolytic treatment in these patients.
Background:
We previously demonstrated that thrombolytic therapy reduces the incidence of significant mitral regurgitation in patients with a first inferior myocardial infarction, but the mechanisms responsible for this decrease were not clear.
Methods:
Wall motion score on two-dimensional echocardiography (16 segments) and mitral regurgitation grade (0 to 3) on Doppler color flow imaging were assessed in 95 patients (in 47 after thrombolysis) at 24 h, 7 to 10 days and 1 month after myocardial infarction. Significant mitral regurgitation was defined as moderate or severe (grade 2 or 3).
Results:
Multivariate analysis revealed that the presence of an advanced wall motion abnormality of the posterobasal segment of the left ventricle was the most significant independent variable associated with significant mitral regurgitation: odds ratio (OR) 15.0, 90% confidence interval (CI) 1.4 to 165.6 at 24 h; OR 2.8, CI 0.9 to 9.3 at 7 to 10 days; OR 4.2, CI 1.2 to 11.4 at 1 month. Thrombolysis reduced the prevalence of advanced wall motion abnormalities in the posterobasal segment at 24 h (55% vs. 75%, OR 0.5, CI 0.2 to 0.99), 7 to 10 days (44% vs. 73%, OR 0.3, CI 0.1 to 0.7) and 1 month (36% vs. 56%, OR 0.4, CI 0.2 to 0.9).
Conclusions:
There is a strong association between advanced wall motion abnormalities in the posterobasal segment and significant mitral regurgitation. In this study group, thrombolysis reduced the prevalence of advanced wall motion abnormalities in the posterobasal segment and thereby reduced the incidence of significant mitral regurgitation.
An ambulance crew attended a patient complaining of chest pain with a clinical picture strongly suggestive of acute myocardial infarction (AMI).
A 12-lead electrocardiogram (ECG) was obtained, which demonstrated ST segment depression of 1 mm in V2–V4 with upright T waves and hyperacute R waves in V1 and V2 (fig 1). A posterior myocardial infarction (MI) was considered and a series of posterior views was obtained to confirm the diagnosis. Leads V7 and V8 revealed ST segment elevation of 1 mm prompting removal to the cardiac catheter laboratory for expert assessment.
Figure 1
Standard ECG showing anterior ST segment depression followed by posterior views revealing ST segment elevation in v7 and v8. …
