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Posterior Myocardial Infarction

Posterior Myocard Infarct

Posterior myocardial infarction represents the end result of myocardial ischemia and coronary insufficiency due to acute obstruction of either right or circumflex coronary arteries. It is difficult to diagnose on classical 12 lead electrocardiogram as it only shows indirect signs. Identifying it is easier when it is associated with inferolateral infarction, which is most often the case, or when posterior leads are used.


Presentation

The acute event in posterior myocardial infarction may be preceded by chest pain that becomes more prolonged and intense progressively and is accompanied by fatigability, malaise or no cardiovascular symptoms. The chest pain is intense, lasts for more than 30- 60 minutes, is located in the retrosternal area and may radiate to the jaw, neck, epigastrium, left shoulder, arm or the inter- scapulovertebral region, in which case, aortic dissection must be considered in the differential diagnosis. The pain is classically described as squeezing, burning, aching, tight, crushing or sharp. Symptoms most usually occur early in the morning, due to sympathetic hyperactivity [1] or after intense effort or distress that causes increased myocardial oxygen demand. Depending on the dimensions of the infarcted area, patients may present with low cardiac output symptoms, such as lightheadedness, syncope, sweating, dyspnea. Associated signs include anxiety, arrhythmia, nausea and vomiting (especially if the inferior wall of the left ventricle is also involved), cough and wheezing. The clinical picture allows, to some degree, outcome prediction, based on risk scores: TIMI (Thrombolysis In Myocardial Infarction) and GRACE (Global Registry of Acute Coronary Events) [2] [3].

Clinical examination may reveal cutaneous pallor or cyanosis, diaphoresis, tachycardia (or bradycardia, in cases where an atrioventricular block coexists), various atrial or ventricular arrhythmias, unequal peripheral pulses (if aortic dissection is present), hypertension (or hypotension, if the pump function is severely impaired), fever [4], new heart murmurs (indicating papillary muscle dysfunction or ventricular septum rupture). Right heart failure signs (jugular distension, peripheral edema, hepatomegaly, pulmonary rales) may appear if the infarcted area has ruptured. This can lead to pericardial bleeding, compression of the right ventricle, and an early death.

Posterior myocardial infarction is not an isolated event, but a progression of an inferolateral infarction. This implies that a large portion of the left ventricle is impaired and early diagnosis is imperative [5] [6].

Coronary Artery Disease
  • These data suggest that the likely substratum for electrocardiographic posterior or inferoposterior infarction is severe circumflex coronary artery disease, usually in association with significant right coronary artery disease.[ncbi.nlm.nih.gov]
  • "Triple rule-out” coronary CT angiography Some institutions are using this protocol that examines for not only coronary artery disease, but also aortic dissection, pulmonary embolism, and other chest diseases.[radiopaedia.org]
  • The patient may or may not have underlying obstructive coronary artery disease (CAD).[emedicine.medscape.com]
  • Globally, acute myocardial infarction is the leading cause of death for both men and women.1 In the United States, one in five deaths is attributed to coronary artery disease.2 What are the signs and symptoms of a patient presenting with acute myocardial[cathlabdigest.com]
  • The most common reason for this event in the adult population is atherosclerotic coronary artery disease.[brilliantnurse.com]
Hepatomegaly
  • Right heart failure signs (jugular distension, peripheral edema, hepatomegaly, pulmonary rales) may appear if the infarcted area has ruptured. This can lead to pericardial bleeding, compression of the right ventricle, and an early death.[symptoma.com]
Chest Pain
  • 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.[ncbi.nlm.nih.gov]
  • The acute event in posterior myocardial infarction may be preceded by chest pain that becomes more prolonged and intense progressively and is accompanied by fatigability, malaise or no cardiovascular symptoms.[symptoma.com]
  • The book is a must for any healthcare professional engaged in the management of the patient with acute chest pain.[books.google.com]
  • Compared to non-PMI STEMI, subjects with PMI were more often female (45% vs 22%; P .02) and less likely to have chest pain (40% vs 75%; P .01).[ncbi.nlm.nih.gov]
  • Patients with chest pain greater than 20 min at rest with either ST depression of at least 0.1 mV in at least one of leads I, aVL or V1-V6 on ECG or STE at least 0.05 mV in at least one posterior lead on the BSM which underwent early SPECT scan.[ncbi.nlm.nih.gov]
Heart Disease
  • diseases Use Additional code to identify presence of hypertension ( I10-I16 ) Ischemic heart diseases I21 ICD-10-CM Diagnosis Code I21 Acute myocardial infarction 2016 2017 2018 - Revised Code 2019 Non-Billable/Non-Specific Code Includes cardiac infarction[icd10data.com]
  • So in general, incomplete bundle branch block should trigger a non-invasive search for underlying heart disease.[ispub.com]
  • Since 95 % of the cases of acute coronary syndrome are manifestations of coronary heart disease, the disease can be prevented.[lecturio.com]
  • Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine . 10th ed. Philadelphia, PA: Elsevier Saunders; 2015. Wijnbergen I, Van't Veer M, Pijls NH, Tijssen J.[emedicine.medscape.com]
  • Ischemic heart disease. In: Diprio JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 8th ed. New York, NY: McGraw-Hill; 2011. Available at: . Accessed September 1, 2014. 7.[ems1.com]
Suggestibility
  • Its association with different varieties of BBB and changes in AH or HV intervals could suggest a relationship with a His-Purkinje conduction disturbance in some patients.[ncbi.nlm.nih.gov]
  • However, histologic examination revealed that the right bundle branch (RBB) had no ischemic involvement, but did show fibrosis, which suggests that this chronic damage of the RBB was a major contributor to the development of RBBB.[ncbi.nlm.nih.gov]
  • The true posterior component of the infarct was clearly diagnosed by detection of pathological Q waves and ST elevations in posterior chest wall maps, whereas right precordial standard leads had shown only suggestive reciprocal changes.[ncbi.nlm.nih.gov]
  • Criteria for distinguishing between posterior wall myocardial infarction and prominent anterior forces in otherwise clinically normal subjects are suggested. These require prospective validation in an independent test population.[ncbi.nlm.nih.gov]
  • This suggested that the precordial decreased ST was not reciprocal to the inferior increased ST, but it was indicative of TP ischemic injury.[ncbi.nlm.nih.gov]

Workup

The electrocardiogram is a reliable method for cardiac ischemia diagnosis, but posterior myocardial infarction is not represented directly on the classical 12 lead recording [7]: horizontal ST depression with tall R and T waves in leads V1-V3 and R/S>1 in V2 [8]. Leads V7-V9 show the classical aspect of ST elevation and Q waves. The ST elevation is usually small, with 0.5 mm being enough to establish the diagnosis because of the increased distance between the posterior leads and the heart. 30% of posterior myocardial infarction patients also develop an atrioventricular ischemic block [9].

After the clinical evaluation and electrocardiogram have raised suspicion of a posterior myocardial infarction, blood tests and echocardiographic evaluation are necessary. Blood workup should include cardiac troponins I or T [10], total creatine kinase and its MB isoenzyme, B-type natriuretic peptide- useful for risk stratification [11], complete blood cell count, lipid profile and complete biochemistry (creatinine, potassium, glucose, lactate dehydrogenase, arterial blood gasses). Cardiac biomarkers should be evaluated in a dynamic manner.

Echocardiography establishes the dimension of the infarction, preexisting abnormal motion areas, the presence of complications: septum, wall or papillary muscle rupture, aneurysms, pericardial effusion or tamponade, etc.

Once the diagnosis is clear, a coronary artery angiography should be performed, with both diagnostic (to establish which artery is occluded and at which level) and therapeutic (emergency angioplasty) intent. If angioplasty is impossible, coronary angiography can establish, based on the status of the peripheral arterial bed, if coronary artery bypass is possible. Multidetector computed tomography coronary angiography is used in acute situations to determine the urgency of treatment and to detect myocardial ischemia in patients without confirmatory findings on ECG or with cardiac markers [12] [13].

Inferior Q Wave
  • Example #2: Old inferior Q-wave MI; note largest Q in lead III, next largest in aVF, and smallest in lead II (indicative of right coronary artery occlusion).[ecg.utah.edu]
  • The presence of Q waves is not always pathologic and up to 12% of healthy young men can have inferior Q waves. 14 Normal Q waves are narrow with a duration of less than 0.04 seconds, and of low amplitude of less than one-third the size of the accompanying[ahcmedia.com]
ST Elevation
  • 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).[ncbi.nlm.nih.gov]
  • The true posterior component of the infarct was clearly diagnosed by detection of pathological Q waves and ST elevations in posterior chest wall maps, whereas right precordial standard leads had shown only suggestive reciprocal changes.[ncbi.nlm.nih.gov]
  • Posterior lead placement V7, V8, V9 The degree of ST elevation seen in V7-9 is typically modest – note that only 0.5 mm of ST elevation is required to make the diagnosis of posterior MI! Example ECG Example 1a Inferolateral STEMI.[lifeinthefastlane.com]
  • Leads V7-V9 show the classical aspect of ST elevation and Q waves.[symptoma.com]
  • Standard ECG: Posterior ECG: Standard ECG: ST elevation in II, III, aVF (inferior) V5, V6 (lateral) with prominent ST depression in V1-V3 and R S in V2 Posterior ECG: ST elevation in V7-V9 Don’t confuse with RV infarction- - ST elevation in inferior leads[emdaily.cooperhealth.org]
Right Bundle Branch Block
  • We present here a patient with the unusual combination of a newly developed right bundle branch block (RBBB) and an acute posterior myocardial infarction (MI).[ncbi.nlm.nih.gov]
  • Also, both patients had complete right bundle-branch block (RBBB) [old in patient 1, new in patient 2], the pattern of which was altered due to the associated PMI.[ncbi.nlm.nih.gov]
  • bundle branch block .[wikidoc.org]
  • Rowlands DJ.Left and right bundle branch block, left anterior and left posterior hemiblock. Eur Heart J. 1984 Mar; 5 Suppl A: 99-105. 10. Fogoros,RN.URL: (July 9, 2006). 11.[ispub.com]
  • Bundle Branch Block Usually easy to recognize because Q waves and ST-T changes are not altered by the RBBB Example #1: Inferior MI RBBB (note Q's in II, III, aVF and rSR' in lead V1) Example #2: Anterior MI with bifascicular block (RBBB LAFB).[ecg.utah.edu]
Prominent A-Wave
  • A common theory is that prominent R-waves may actually represent inverted Q-waves. 1,8 Interestingly, over a third of patients had prominent R-waves in either V1 or V2.[bjcardio.co.uk]
  • R waves in V1-V3, R/S wave ratio 1.0 in lead V2, upright T-waves in V1-V3, often coexisting inferior or lateral MI.[errolozdalga.com]
  • [1] R/S wave ratio 1.0 in lead V2 Co-existing acute, inferior, and/or lateral MI Limited to leads V1 – V3: ST-segment depression (horizontal moreso than downsloping or upsloping) Prominent R wave Prominent, upright T wave Combination of horizontal ST-segment[foamem.com]
  • 1 R/S wave ratio 1.0 in lead V2 Co-existing acute, inferior, and/or lateral MI Limited to leads V1 – V3: ST-segment depression (horizontal moreso than downsloping or upsloping) Prominent R wave Prominent, upright T wave Combination of horizontal ST-segment[aliem.com]
  • R-waves in leads V1-V3 R/S ratio 1 in lead V2 Co-existing acute inferior and/or lateral myocardial infarction Figure 1 Logically, it makes sense that if we cannot visualize the posterior heart via the standard ECG we should devise a direct way to evaluate[emdocs.net]
Electrocardiogram Change
  • Findings: Septal MI Anatomic Distribution Electrocardiogram Changes Lead V1 to lead V2 Distribution Left Coronary Artery : LAD-Septal Branch Complications Infranodal and Bundle Branch Block X.[fpnotebook.com]

Treatment

  • Seite 43 - Executive Summary of the Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III... ‎[books.google.com]
  • This may lead to a more robust identification of posterior myocardial infarction that, in turn, may allow for adequate treatment and triage.[ncbi.nlm.nih.gov]
  • Multidetector computed tomography coronary angiography is used in acute situations to determine the urgency of treatment and to detect myocardial ischemia in patients without confirmatory findings on ECG or with cardiac markers.[symptoma.com]
  • This review will highlight the electrocardiographic fine-tuned diagnosis of posterior myocardial infarction by using the posterior leads V(7) to V(9) leading to easier and faster recognition with consequences for treatment and improved prognosis.[repository.ubn.ru.nl]
  • Detailed discussions of hot topics, full-color illustrations, and a DVD of procedural video clips, animations, and downloadable image libraries help you provide fast, appropriate treatment for each challenging case you face.[books.google.com]

Prognosis

  • Gender differences in management and prognosis were assessed by stepwise multiple logistic regression analysis. University, large-volume, tertiary hospital.[ncbi.nlm.nih.gov]
  • Diagnosis of posterior myocardial infarction may be facilitated by using the posterior leads V(7) to V(9), leading to easier and faster recognition with consequences for treatment and improved prognosis.[patient.info]
  • This review will highlight the electrocardiographic fine-tuned diagnosis of posterior myocardial infarction by using the posterior leads V(7) to V(9) leading to easier and faster recognition with consequences for treatment and improved prognosis.[repository.ubn.ru.nl]
  • By definition, patients in quadrant 4 are in "cardiogenic shock" and have a poor prognosis, unless they have a correctable mechanical complication, or unless they are early into the course of their MI, and some of the ischemic myocardium is recovered[brown.edu]
  • Incidence and prognosis of unrecognised myocardial infarction. An update on the Framingham Study. N Engl J Med 1984; 311:1144-1147. 5. Kannel WB. Silent myocardial ischemia and infarction: insights from the Framingham Study.[ispub.com]

Etiology

  • Etiology of Myocardial Infarction Causes of myocardial infarction The main cause of myocardial infarction is the development of atherosclerosis in the coronary arteries, hence the name coronary heart disease . Coronary embolism is a more rare cause.[lecturio.com]
  • The usual etiology for a myocardial infarction is atherosclerotic heart disease; however there are other reasons for patients to have an MI. Acute coronary syndrome is divided into unstable angina, NSTEMI, and STEMI.[brilliantnurse.com]
  • (See Etiology for details.) The electrocardiographic (ECG) results of an acute MI are seen below. Acute inferior myocardial infarction.[emedicine.medscape.com]

Epidemiology

  • Epidemiology It is difficult to be sure of the percentage of myocardial infarctions that are posterior because it seems likely that many are missed. [ 3 ] The risk factors are the same for any cardiovascular disease, such as smoking, hypertension, diabetes[patient.info]
  • Epidemiology of Myocardial Infarction Spread of myocardial infarction Myocardial infarction is one of the most common causes of death in industrialized countries. Several million people suffer from myocardial infarction each year.[lecturio.com]
  • Intrauterine MI also does occur, often in association with coronary artery stenosis. [25] Epidemiology United States statistics Coronary artery disease (CAD) is the leading cause of death in the United States; approximately 500,000-700,000 deaths related[emedicine.medscape.com]
Sex distribution
Age distribution

Pathophysiology

  • Thus, it is gratifying to note the contribution of the ECG to diagnostics, the only modality that provided a pathophysiologic insight in these two patients who appeared to be abruptly deteriorating clinically without an apparent reason.[ncbi.nlm.nih.gov]
  • Pathophysiology A posterior MI is due to occlusion of the left circumflex artery .[wikidoc.org]
  • Pharmacotherapy: A Pathophysiologic Approach. 8th ed. New York, NY: McGraw-Hill; 2011. Available at: . Accessed September 1, 2014. 7. Clinical Pharmacology [database online]. Tampa, FL: Gold Standard Inc.; 2011. . Accessed September 1, 2014. 8.[ems1.com]
  • Pathophysiology of Myocardial Infarction How does myocardial infarction happen? As a result of atherosclerosis, plaques start to form in the coronary arteries, which are at first still stable.[lecturio.com]
  • These pathophysiologic responses lead the patient to the triad of “classic” symptoms that are associated with this disease process.[brilliantnurse.com]

Prevention

  • The Heart Outcomes Prevention Evaluation Study Investigators. N Engl J Med 2000 342, 145-53. ‎ Seite 35 - Study Investigators.[books.google.com]
  • A posterior myocardial infarction (PMI) is associated with significant morbidity and delays in recognition may prevent the timely revascularization of these patients.[ncbi.nlm.nih.gov]
  • Delay in diagnosis may also contribute. [ 7 ] Prevention See the separate Prevention of Cardiovascular Disease article.[patient.info]
  • Secondary Prevention Secondary prevention has a key role in the management of STEMI.[aafp.org]
  • NICE's guidelines on unstable angina and NSTEMI: early management (CG94), myocardial infarction: cardiac rehabilitation and prevention of further cardiovascular disease (CG172) and myocardial infarction with ST-segment elevation: acute management (CG167[nice.org.uk]

References

Article

  1. Wijnbergen I, Van't Veer M, Pijls NH, et al. Circadian and weekly variation and the influence of environmental variables in acute myocardial infarction. Neth Heart J. 2012;20(9):354-9.
  2. Amsterdam EA, Wenger NK, Brindis RG, et al. 2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2014;130(25):e344-426.
  3. Roffi M, Patrono C, Collet JP, et al. 2015 ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation: Task Force for the Management of Acute Coronary Syndromes in Patients Presenting without Persistent ST-Segment Elevation of the European Society of Cardiology (ESC). Eur Heart J. 2016;37 (3):267-315.
  4. Patel MR, Mahaffey KW, Armstrong PW, et al. Prognostic usefulness of white blood cell count and temperature in acute myocardial infarction (from the CARDINAL Trial). Am J Cardiol. 2005;95 (5):614-618.
  5. Oraii S, Maleki M, Abbas Tavakolian A, et al. Prevalence and outcome of ST-segment elevation in posterior electrocardiographic leads during acute myocardial infarction. J Electrocardiol 1999;32: 275-278.
  6. Matetzky S, Freimark D, Chouraqui P, et al. Significance of ST segment elevations in posterior chest leads (V7 to V9) in patients with acute inferior myocardial infarction: application for thrombolytic therapy. J Am Coll Cardiol 1998;31:506-511.
  7. Rich M, Imburgia M, King T, et al. Electrocardiographic diagnosis of remote posterior wall myocardial infarction using unipolar posterior lead V9 Chest 1989;96:489-493.
  8. Boden E, Kleiger R, Gibson R, et al. Electrocardiographic evolution of posterior acute myocardial infarction: Importance of early precordial ST-segment depression. Am J Cardiol 1987;59:782-787.
  9. Eisenstein I, Sanmarco M, Madrid W, et al. Electrocardiographic and vectorcardiographic diagnosis of posterior wall myocardial infarction. Chest 1988;3:409-416
  10. Mueller C. Biomarkers and acute coronary syndromes: an update. Eur Heart J. 2014;35(9):552-556.
  11. Haaf P, Reichlin T, Corson N, et al. B-type natriuretic peptide in the early diagnosis and risk stratification of acute chest pain. Am J Med. 2011;124 (5):444-52.
  12. Goldstein JA, Chinnaiyan KM, Abidov A, et al, for the CT-STAT Investigators. The CT-STAT (Coronary Computed Tomographic Angiography for Systematic Triage of Acute Chest Pain Patients to Treatment) trial. J Am Coll Cardiol. 2011;58 (14):1414-1422.
  13. Samad Z, Hakeem A, Mahmood SS, et al. A meta-analysis and systematic review of computed tomography angiography as a diagnostic triage tool for patients with chest pain presenting to the emergency department. J Nucl Cardiol. 2012;19 (2):364-376.

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Last updated: 2018-06-21 18:46