Myocardial Infarction - Diagnosis


Medical societies recommend that the physician confirm that a patient is at high risk for myocardial infarction before conducting imaging tests to make a diagnosis. Patients who have a normal ECG and who are able to exercise, for example, do not merit routine imaging. Imaging tests such as stress radionuclide myocardial perfusion imaging or stress echocardiography can confirm a diagnosis when a patient's history, physical exam, ECG and cardiac biomarkers suggest the likelihood of a problem.

The diagnosis of myocardial infarction can be made after assessing patient's complaints and physical status. ECG changes, coronary angiogram and levels of cardiac markers help to confirm the diagnosis. ECG gives valuable clues to identify the site of myocardial damage while coronary angiogram allows visualization of narrowing or obstructions in the heart vessels. At autopsy, a pathologist can diagnose a myocardial infarction based on anatomopathological findings.

A chest radiograph and routine blood tests may indicate complications or precipitating causes and are often performed upon arrival to an emergency department. New regional wall motion abnormalities on an echocardiogram are also suggestive of a myocardial infarction. Echo may be performed in equivocal cases by the on-call cardiologist. In stable patients whose symptoms have resolved by the time of evaluation, Technetium (99mTc) sestamibi (i.e. a "MIBI scan") or thallium-201 chloride can be used in nuclear medicine to visualize areas of reduced blood flow in conjunction with physiologic or pharmacologic stress. Thallium may also be used to determine viability of tissue, distinguishing whether non-functional myocardium is actually dead or merely in a state of hibernation or of being stunned.

WHO criteria formulated in 1979 have classically been used to diagnose MI; a patient is diagnosed with myocardial infarction if two (probable) or three (definite) of the following criteria are satisfied:

  1. Clinical history of ischaemic type chest pain lasting for more than 20 minutes
  2. Changes in serial ECG tracings
  3. Rise and fall of serum cardiac biomarkers such as creatine kinase-MB fraction and troponin

The WHO criteria were refined in 2000 to give more prominence to cardiac biomarkers. According to the new guidelines, a cardiac troponin rise accompanied by either typical symptoms, pathological Q waves, ST elevation or depression, or coronary intervention is diagnostic of MI.

Read more about this topic:  Myocardial Infarction

Other articles related to "diagnosis":

Major Diagnostic Category
... dividing all possible principal diagnoses (from ICD-9-CM) into 25 mutually exclusive diagnosis areas ... (Multiple Significant Trauma) with at least two significant trauma diagnosis codes (either as principal or secondaries) from different body site categories ... MDC 25 (HIV Infections) must have a principal diagnosis of an HIV Infection or a principal diagnosis of a significant HIV related condition and a secondary ...
Pheochromocytoma - Diagnosis
... The diagnosis can be established by measuring catecholamines and metanephrines in plasma (blood) or through a 24-hour urine collection ...
Sexual Fetishism - Modern Theory and Treatment - Diagnosis
... It is sufficient for the diagnosis if one of the participants is being hurt or mistreated in any other way ... A correct diagnosis in terms of the ICD manual stipulates hierarchical proceeding ... Still today, arguments go on whether a specific diagnosis fetishism is needed at all or if paraphilia as such is sufficient ...
Taser - Excited Delirium
... Taser safety issues Some of the deaths associated with tasers are given a diagnosis of excited delirium, a term for a phenomenon that manifests as a ... The diagnosis of excited delirium has been controversial ... by some medical examiners for several years, mainly as a diagnosis of exclusion established on autopsy ...
Rosenhan Experiment - Impact and Controversy
... Rosenhan published his findings in Science, criticizing the reliability of psychiatric diagnosis and the disempowering and demeaning nature of patient care experienced ... Many defended psychiatry, arguing that as psychiatric diagnosis relies largely on the patient's report of their experiences, faking their presence no more demonstrates problems with ...