Acute myocardial infarction diagnosis

Wagner et. al (46) studied 376 patients to evaluate the importance of identification of the myocardial-specific MB isoenzyme in the diagnosis of acute myocardial infarction. An attempt was made to determine the incidence of falsely positive (mb). No acute infarction was diagnosed in all patients in whom neither total CK nor the isoenzymes of LD indicated myocardial necrosis. Incidence of falsely negative (MB) was zero in 33 patients. They concluded that determination of the isoenzymes of CK provides both a sensitive and specific indication of acute myocardial infarction. 

Ronttinen, A. and Somer, H. Specificity of seriim creatine kinse isoenzymes in diagnosis of acute myocardial infarction. Br. Med. J. (1973), 1, 386-389. 

Atropine can be used in the differential diagnosis of S-A node dysfunction. If sinus bradycardia is due to extracardiac causes, atropine can generally elicit a tachy-cardic response, whereas it cannot elicit tachycardia if the bradycardia results from intrinsic causes. Under certain conditions, atropine may be useful in the treatment of acute myocardial infarction. Bradycardia frequently occurs after acute myocardial infarction, especially in the first few hours, and this probably results from excessive vagal tone. The increased tone and bradycardia... 

The proper selection of patients for thrombolytic therapy is critical. The diagnosis of acute myocardial infarction is made clinically and is confirmed by electrocardiography. Patients with ST-segment elevation and bundle branch block on electrocardiography have the best outcomes. All trials to date show the greatest benefit for thrombolytic therapy when it is given early, within 6 hours after symptomatic onset of acute myocardial infarction. 

Aortic arch dissection can cause profound hypotension, with global, and sometimes boundary zone, cerebral ischemia or focal cerebral ischemia if the dissection spreads up one of the neck arteries. Clues to this diagnosis are anterior chest or interscapular pain, along with diminished, unequal or absent arterial pulses in the arms or neck and a normal electrocardiogram, unlike acute myocardial infarction, acute aortic regurgitation and pericardial effusion. 

The application of antibodies in cardiovascular targeting in vivo originated with the experimental demonstration of the feasibility of using radiolabeled antimyosin antibody for diagnosis of acute myocardial infarction in 1976. Since then, the use of antibodies in the cardiovascular system has encompassed imaging of myocarditis,heart transplant rejection, dilated cardiomyopathy, alcohol induced cardiomyopathy,adriamycin cardiotoxicity, various other cardiomyopathies, vascular clots, atherosclerotic lesions,and even certain cancers such as soft tissue sarcomas.f Yet the best characterized and studied antibody for cardiovascular diagnostic targeting is monoclonal antimyosin Fab for its exquisite specificity... 

Blankenship JC, Almquist AK. Cardiovascular complications of thrombolytic therapy in patients with a mistaken diagnosis of acute myocardial infarction. J Am Coll Cardiol 1989 14(6) 1579-82. 

ENI6 Collins, R. and Tucker, J. (1991). Myoglobin and CK-MB tests for the diagnosis of acute myocardial infarction in emergency room patients. Clin. Chem. 37, 978, Abstr. 322. 

In the second scenario, the test result excludes a diagnosis this is referred to as a rule-out test. The actions resulting from excluding a diagnosis will invariably involve the evaluation or creation of another hypothesis. When a patient is admitted with atypical chest pain and acute myocardial infarction is suspected, the measurement of troponin maybe used to rule out (or rule in) acute myocardial necrosis. 

The changes of serum CK and its MB isoenzyme following a myocardial infarction are discussed in Chapter 44. Other cardiac conditions have been reported to increase serum CK and CK-MB in serum. These conditions include cardioversion, cardiopulmonary bypass and coronary artery bypass surgery, cardiac transplantation, myocarditis, pericarditis, and pulmonary embolism. Despite improvements, in the diagnostic performance and practicality of CK and CK-MB assays, there is no controlled cUnicai impact trial showing that these tests are effective for decisions to send a patient home or to the appropriate level of care of admission for patients with suspected acute cardiac ischemia, either as one-time or serial tests.For diagnosis of acute myocardial infarction, it is now advantageous to use more cardiac-specific nonenzymatic tests, such as cardiac troponin I orT. 

Figure 44-24 ROC curves for A cTnT, CK-MB, and myoglobin and B CK-MB and cTnl for diagnosis of acute myocardial infarction, according to sample time from admission (0 hours).

Cummins B, Auckland ML, Cummins P. Cardiac specific troponin I radioimmunoassay in the diagnosis of acute myocardial infarction. Am Heart J 1987 113 1333-44. 

Galen RS, Reiffel JA, Gambino SR. Diagnosis of acute myocardial infarction relative efficiency of serum enzyme and isoenzyme measurements. JAMA 1975 232 145-7. 

Newby LK, Alpert JS, Ohman EM, Thygesen K, Califf RM. Changing the diagnosis of acute myocardial infarction implications for practice and clinical investigations. Am Heart J 2002 144 957-80. 

Wu AHB, Valdez R Jr, Apple FS, Gornet T, Stone MA, Mayfield-Stokes S, et al. Cardiac troponin T immunoassay for diagnosis of acute myocardial infarction. Clin Chem 1994 40 900-7. 

Brandt RR, Hammill ST, Higano ST. Images in cardiovascular medicine electrocardiographic diagnosis of acute myocardial infarction during ventricular pacing. Circulation 1998 97 2274. 

Lopez-Sendon J, Gonzalez A, Lopez de Sa E et al. Diagnosis of subacute ventricular wall rupture after acute myocardial infarction sensitivity and specificity of clinical, hemodynamic and echocardiographic criteria. J Am Coll Cardiol 1992 19 1145. 

Madias J, Sinha A, Ashtiani R. A critique of the new ST-segment criteria for the diagnosis of acute myocardial infarction in patients with left bundle-branch block. Clin Cardiol 2001 24 652. 

Menown L, McKenzie G, Adgey A. Optimizing the initiall2-lead electrocardiographic diagnosis of acute myocardial infarction. Eur Heart J 2000 21 275. 

Schmitt C, Gunter L, Scmieder S, Karch M, Neuman FJ, Schomig A. Diagnosis of acute myocardial infarction in... 

Sgarbossa E, Pinski S, Gates K, Wagner G. Early ECG diagnosis of acute myocardial infarction in the presence ofventricular paced rhythm. Am J Cardiol 1996a 77 423. 

Sgarbossa EB, Birnbaum Y, Parrilo JF. Electrocardiographic diagnosis of acute myocardial infarction current concepts for the clinician. Am Heart J 2001 141 507. 

Khaw, B. A. (1994) Antimyosin antibody for the diagnosis of acute myocardial infarction experimental validation, in Monoclonal Antibodies in Cardiovascular Diseases (Khaw, B. A., Narula, J., and Strauss, H. W., eds.), Lea and Febiger, Malvern, PA, pp. 15-29. 

Anne Jeina. Mrs. Jeina s diagnosis of an acute myocardial infarction J (MI) was based partly on measurements of CK-MB, myoglobin, and cTN- T (the cardiac isozyme of troponin-T, a subunit of the regulatory protein... 

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