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].
Entire Body System
- Anemia
A problem of oxygen supply and demand, such as coronary spasm, coronary embolism, arrhythmia, anemia, or hypotension. 3. [mdedge.com]
Reversible causes of the heart failure also need to be addressed (e.g. infection, alcohol ingestion, anemia, thyrotoxicosis, arrhythmia, hypertension). [en.wikipedia.org]
It is mostly caused by demand ischemia where energy supply to cardiomyocytes is insufficient for the work force, e.g. during extreme hypertension, aortic valve stenosis, extreme left ventricular hypertension, anemia, atrial fibrillation with rapid ventricular [en.ecgpedia.org]
Anemia with secondary ischemia. [ecgwaves.com]
Type 2: The infarction is related to ischemia, the cause of the ischemia being by e.g. coronary embolism or anemia Type 3: The symptoms preceding cardiac death or an autopsy point to myocardial ischemia. [lecturio.com]
- Sepsis
Summaries Written Summaries Rapid Reviews Videos Videos Rapid Reviews Videos POCUS Cases EMU 365 COVID-19 Update Apr 19, 2020 Update April 12, 2020 Update April 5, 2020 Update March 29, 2020 Update March 23, 2020 Podcasts & Show Notes COVID Surviving Sepsis [emergencymedicinecases.com]
Fourth, patients with reasons to have demand ischemia (tachycardia, sepsis, GI Bleed, etc.) are much more likely to have subendocardial ischemia (like in a stress test); those with posterior MI are much more likely to present with onset of chest pain [hqmeded-ecg.blogspot.com]
[…] chronic heart failure Electrical cardioversion Takotsubo cardiomyopathy Pericarditis and myocarditis (perimyocarditis) Ablation procedures Supraventricular tachyarrhythmia Ventricular tachyarrhythmia Bradyarrhythmia Stroke, subarachnoidal hemorrhage Sepsis [ecgwaves.com]
However, ischemia may also occur due to either increased oxygen demand or decreased supply and is called type II myocardial infarction; this may be triggered by many conditions such as hypertension, hypotension, coronary artery spasm, anemia, sepsis, [statpearls.com]
Nonatherosclerotic causes of MI include the following: Coronary occlusion secondary to vasculitis Ventricular hypertrophy (eg, left ventricular hypertrophy, hypertrophic cardiomyopathy) Coronary artery emboli, secondary to cholesterol, air, or the products of sepsis [emedicine.medscape.com]
- Coronary Atherosclerosis
Associations of coronary heart disease risk factors with the intermediate lesion of atherosclerosis in youth. The Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Research Group. [emedicine.medscape.com]
- Hypoxemia
A fixed atherosclerotic lesion in a vessel supplying cardiac tissue that experiences increased oxygen demand (e.g., tachycardia, hypotension, hypoxemia, among others) may produce myocardial ischemia. [ncbi.nlm.nih.gov]
(eg, cocaine, amphetamines, ephedrine) Arteritis Coronary anomalies, including aneurysms of coronary arteries Factors that increase oxygen requirement, such as heavy exertion, fever, or hyperthyroidism Factors that decrease oxygen delivery, such as hypoxemia [emedicine.medscape.com]
- Amyloidosis
[…] tachyarrhythmia Ventricular tachyarrhythmia Bradyarrhythmia Stroke, subarachnoidal hemorrhage Sepsis (septic shock) Intoxication Extreme physical exercise Aortic dissection Rhabdomyolysis with myocardial damage Pulmonary embolism Severe pulmonary hypertension Amyloidosis [ecgwaves.com]
Additionally, infiltrative disorders such as amyloidosis and connective tissue diseases such as systemic lupus erythematosus have similar consequences. [en.wikipedia.org]
Gastrointestinal
- Abdominal Pain
However, infarction pain can also be atypical, such as upper abdominal pain, feeling of faintness combined with fear and sweating, dyspnea, nausea or vomiting. These atypical pain symptoms are frequently found in women, diabetics or older people. [lecturio.com]
[…] exam Tenderness in the abdomen should prompt concern for intra-abdominal etiology (cholecystitis, pancreatitis, GERD), which may lead to radiation of pain into the chest or difficulty differentiating visceral abdominal pain from chest pain. [statpearls.com]
FIELD DIAGNOSIS OF RVI Aside from questions about area of infarct, any patient who presents with chest pain, shortness of breath, unexplained hypotension, abdominal pain, back pain in the scapular or subscapular region, epigastric pain, neck or jaw pain [emsworld.com]
Cardiovascular
- 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]
[…] into the chest or difficulty differentiating visceral abdominal pain from chest pain. [statpearls.com]
He presented at 1810 with chest pain 5 days after stopping clopidogrel (on the instructions of another physician). [hqmeded-ecg.blogspot.com]
Case 1: 80yo with one day weak/dizzy, no prior ECG Cases 2: Same patient years later, with acute chest pain Case 3: 40yo acute chest pain with diaphoresis, no prior ECG Case 4: 75yo acute chest pain, no prior ECG Case 5: 60yo with acute chest pain, old [emergencymedicinecases.com]
A 60 year old woman with 3 hours of chest pain. [ecglibrary.com]
- Heart Disease
Session Title: Acute and Stable Ischemic Heart Disease: Clinical 5 Abstract Category: 02. Acute and Stable Ischemic Heart Disease: Clinical Presentation Number: 1330-370 2019 American College of Cardiology Foundation [onlinejacc.org]
Our Specialty Centers The Johns Hopkins Ciccarone Center for the Prevention of Heart Disease takes a multidisciplinary approach to helping you prevent heart disease and stroke—and that includes getting your cholesterol in check. [hopkinsmedicine.org]
Ischemic heart 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 [icd10data.com]
- Thrombosis
Late stent thrombosis, although not very often, is a very serious complication and can lead to death or acute myocardial infarction. [europeana.eu]
There was extensive mural thrombosis Mural thrombosis is the formation of multiple thrombi along an injured endocardial wall. and reactive pericarditis Pericarditis is inflammation of the pericardium - often with deposition of fibrin.. [peir.path.uab.edu]
[…] posterior wall MI occurs when posterior myocardial tissue (now termed inferobasilar), usually supplied by the posterior descending artery — a branch of the right coronary artery in 80% of individuals — acutely loses blood supply due to intracoronary thrombosis [healio.com]
[…] dramatically reduced concerns about late stent thrombosis. [en.wikipedia.org]
Myocardial infarction is a consequence of atherosclerosiscoronary vessels, or rather, such complications as embolism and thrombosis. The cause may serve as a spasmodic phenomenon in the arterial vessels of the heart. [trendexmexico.com]
- Gallop Rhythm
[…] the Heart Rhythm Society. [en.wikipedia.org]
Musculoskeletal
- Contusion
Trauma/contusion. Post-thoracotomy. Neurogenic pain. Psychiatric: Acute/chronic stress. Anxiety. Depression. Other: Herpes Zoster. Anemia with secondary ischemia. [ecgwaves.com]
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].
QRS Wave
- Inferior Q Wave
(necrosis) (Pathologic Q waves are usually defined as duration ≥ 0.04 s or ≥ 25% of R-wave amplitude) Pathologic Q waves, T wave inversion (necrosis and fibrosis) Pathologic Q waves, upright T waves (fibrosis) Inferior MI Family (includes inferior, true [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]
QT, RR, ST Intervals
- ST Elevation
INTRODUCTION: 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]
Post Ischemic T wave changes ST elevation MI Non-ST Elevation Infarction Dr. [slideshare.net]
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 [emdaily.cooperhealth.org]
Because posterior electrical activity is recorded from the anterior side of the heart, the typical injury pattern of ST elevation and Q waves becomes inverted: ST elevation becomes ST depression Q waves become R waves Terminal T-wave inversion becomes [lifeinthefastlane.com]
Rhythm
- Early Repolarization
In some cases the slope is downward (convex), which can be confused with early repolarization. [ahcmedia.com]
Repolarization in young men Men age >40 years old V1-V2 ST Elevation >2 mm Women V1-V2 ST Elevation >1.5 mm Deep symmetric T-wave inversion Occurs in multiple precordial leads Left main Coronary Artery stenosis marker ST Depression >1 mm in 8 or more [fpnotebook.com]
Electrocardiographic differentiation of early repolarization from subtle anterior ST-segment elevation myocardial infarction. Ann Emerg Med 2012;60:45–56. https://doi.org/10.1016/j.annemergmed.2012.02.015 5. [bjcardio.co.uk]
repolarization, pericarditis, hyperkalemia, and ventricular aneurysm. [6] [7] [8] There are heavily researched clinical decision tools such as the TIMI Scores which help prognose and diagnose STEMI based on clinical data. [en.wikipedia.org]
Blocks
- Right Bundle Branch Block
Discussion Ventricular repolarization in right bundle branch block Right bundle branch block is an intra-ventricular conduction delay or block at the right bundle branch and thus depolarization takes place through the unspecific muscle generating a ‘jumping [academic.oup.com]
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]
R waves of 0.04 second or R/S ratios equal to or greater than one in lead V1 were also found in the normal child, complete right bundle-branch block, the Wolff-Parkinson-White syndrome with an anteriorly directed delta wave, right ventricular hypertrophy [ahajournals.org]
Hypertrophy
- Ventricular Hypertrophy
Differentiating posterolateral ischemia from right ventricular hypertrophy (RVH) It is occasionally difficult to differentiate right ventricular hypertrophy (RVH) from posterolateral ischemia. [ecgwaves.com]
Abstract Electrocardiographic tall R waves in the right precordial leads may be present in patients with posterior wall myocardial infarction, right ventricular hypertrophy, various conduction disturbances, some forms of cardiomyopathy, and in clinically [ncbi.nlm.nih.gov]
R waves of 0.04 second or R/S ratios equal to or greater than one in lead V1 were also found in the normal child, complete right bundle-branch block, the Wolff-Parkinson-White syndrome with an anteriorly directed delta wave, right ventricular hypertrophy [ahajournals.org]
Other causes of similar ECG changes include: Right ventricular hypertrophy can cause large R waves in the early V leads. Infarction of the right ventricle is rare but will produce a similar ECG. [patient.info]
The strain pattern of left ventricular hypertrophy (by voltage). D. Left main acute coronary syndrome pattern. Ansewr: A. Acute posterior wall myocardial infarction. [patientcareonline.com]
Other ECG Findings
- Electrocardiogram Change
[…] ischaemia NOS (finding), Electrocardiogram finding of ischemia (finding), Electrocardiogram finding of ischemia, ECG: myocardial ischaemia (finding), Electrocardiogram: myocardial ischaemia NOS, Electrocardiogram: myocardial ischemia NOS, Electrocardiogram [fpnotebook.com]
Treatment
الصفحة 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]
If you've had prior heart treatments Even if you've been treated for a prior heart attack or if you've had other treatments for coronary artery disease, a heart attack CAN happen again. [my.clevelandclinic.org]
The goals of treatment are to preserve the heart muscle and to relieve pain, as the pain forces the heart to work harder. [hopkinsmedicine.org]
This may lead to a more robust identification of posterior myocardial infarction that, in turn, may allow for adequate treatment and triage. To read this article in full you will need to make a payment References Brady J.W. Erling B. [ajemjournal.com]
Prognosis
Gender differences in management and prognosis were assessed by stepwise multiple logistic regression analysis. SETTING: University, large-volume, tertiary hospital. [ncbi.nlm.nih.gov]
Key words: Myocardial Infarction; Electrocardiography; Diagnosis; Coronary Angiography; Risk Assessment; Myocardial Revascularization; Myocardial Reperfusion; Diagnostic Errors; Prognosis Uvod. [go.gale.com]
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]
Pathophysiology of Reperfusion Gross Pathology Histopathology Causes Differentiating ST elevation myocardial infarction from other Diseases Epidemiology and Demographics Risk Factors Triggers Natural History and Complications Risk Stratification and Prognosis [wikidoc.org]
Etiology
Distant heart sounds may be a result of pericardial effusion, which should raise suspicion of other etiologies like dissection and subsequent hemopericardium. [statpearls.com]
Etiology PMI typically results from a reduction or cessation of blood flow to one or several of the coronary arteries. Normally, oxygenated blood is supplied to the coronary arteries after leaving the left ventricle. [ncbi.nlm.nih.gov]
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]
Infarction Microchapters Home Patient Information Overview Pathophysiology Pathophysiology of Vessel Occlusion Pathophysiology of Reperfusion Gross Pathology Histopathology Causes Differentiating ST elevation myocardial infarction from other Diseases Epidemiology [wikidoc.org]
Summaries Rapid Reviews Videos Videos Rapid Reviews Videos POCUS Cases EMU 365 COVID-19 Update Apr 19, 2020 Update April 12, 2020 Update April 5, 2020 Update March 29, 2020 Update March 23, 2020 Podcasts & Show Notes COVID Surviving Sepsis Guidelines Ep 141 Epidemiology [emergencymedicinecases.com]
"Epidemiology of atrial fibrillation: European perspective". Clinical Epidemiology. 6: 213–20. doi:10.2147/CLEP.S47385. PMC 4064952. PMID 24966695. ^ GBD 2013 Mortality and Causes of Death, Collaborators (17 December 2014). [en.wikipedia.org]
Pathophysiology
Acute Coronary Syndrome Main Page ST Elevation Myocardial Infarction Microchapters Home Patient Information Overview Pathophysiology Pathophysiology of Vessel Occlusion Pathophysiology of Reperfusion Gross Pathology Histopathology Causes Differentiating [wikidoc.org]
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]
Isolated Posterior Wall ST Segment Elevation AMI Posterior wall myocardial infarction refers to infarction of the dorsal area of the left ventricle and, in most cases, pathophysiologically involves either the left circumflex or the right coronary artery [journals.lww.com]
Pharmacotherapy: A Pathophysiologic Approach. 8th ed. New York, NY: McGraw-Hill; 2011. Available at: http://www.accesspharmacy.com.proxy.cc.uic.edu/content.aspx?aID=7971879. Accessed September 1, 2014. 7. Clinical Pharmacology [database online]. [ems1.com]
The common pathophysiology involves a sudden rupture or erosion of an atheromatous plaque within the wall of a coronary artery. [phildrummer64.wordpress.com]
Prevention
The Heart Outcomes Prevention Evaluation Study Investigators. N Engl J Med 2000 342, 145-53. الصفحة 35 - Study Investigators. [books.google.com]
BACKGROUND: 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]
Our Specialty Centers The Johns Hopkins Ciccarone Center for the Prevention of Heart Disease takes a multidisciplinary approach to helping you prevent heart disease and stroke—and that includes getting your cholesterol in check. [hopkinsmedicine.org]
In: Secondary prevention of ischaemic cardiac event. Clinical Evidence 2002;7:124-160. [30] Keeley EC, Boura JA, Grines CL. [tankonyvtar.hu]
References
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- Eisenstein I, Sanmarco M, Madrid W, et al. Electrocardiographic and vectorcardiographic diagnosis of posterior wall myocardial infarction. Chest 1988;3:409-416
- Mueller C. Biomarkers and acute coronary syndromes: an update. Eur Heart J. 2014;35(9):552-556.
- 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.
- 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.
- 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.