Heart Attack Diagnosis

Diagnosis and treatment tend to occur at the same time in patients who are experiencing chest pain. If there is concern that heart muscle is at risk, delays need to be minimized so that blood supply to that muscle can be restored.

Medical History
The diagnosis of angina is made by history of the patient. If the story that the patient tells is suggestive of cardiac ischemia (cardiac= heart + ischemia= decreased blood supply), then the health care practitioner will continue on the path to determine whether a heart attack has occurred.
Important questions include:

1. When did the pain start?
   
   
2. What were you doing?
   
   
3. Did you have to stop?
   
   
4. Did the pain get better with rest?
   
   
5. Did the pain come back with activity?
   
   
6. Did the pain stay in your chest or did it move somewhere else, like the jaw, teeth, arm or back?
   
   
7. Did you get short of breath?
   
   
8. Did you become nauseous?
   
   
9. Were you sweating profusely?

The medical history also includes assessing risk factors for heart disease, including:

• smoking,
  
  
• hypertension or high blood pressure,
  
  
• high cholesterol,
  
  
• diabetes,
  
  
• previous history of other blood vessel problems such as stroke or peripheral vascular disease, and/or
  
  
• a family history of heart disease, especially at an early age.

Questions may be asked about changes in exercise tolerance that might provide clues as to whether heart disease is present:

1. Have there been episodes of previous chest pain?
   
   
2. Is there shortness of breath on exertion?
   
   
3. Can you walk to get the mail?
   
   
4. Can you climb a flight of stairs?

The questions may try to distinguish between stable angina and unstable angina. Stable angina tends to be predictable. For example, it may occur after climbing a flight of stairs or walking a couple of blocks and then resolves quickly with rest. Unstable angina may occur without warning when the body is at rest and the heart is not stressed, for example while sitting or sleeping.
Anginal symptoms that change and occur with less activity or sound unstable are worrisome and may be due to increased narrowing of a coronary artery.
Since other diagnoses will be considered, some questions may be asked to identify potential symptoms of conditions such as reflux esophagitis (GERD), gastritis, trauma, pulmonary embolus (blood clot in the lung), or pneumonia.

Physical examination
While the diagnosis is based on history, the physical exam can give some clues.

• Are the blood pressure and pulse rate normal?
  
  
• Do the lungs sound clear?
  
  
• Are there findings suggestive of an infection (pneumonia) or fluid (edema)?
  
  
• Are there unusual heart sounds? New murmurs can be associated with heart attack.
  
  
• Are bruits (noises produced by narrowed blood vessels that are heard with a stethoscope) present when listening to the neck, abdomen, or groin?
  
  
• Is there tenderness in the abdomen that would suggest the chest pain is due to gallbladder, pancreas, or ulcer disease?

EKGs, blood tests, and chest X-ray are other tests that are likely to be performed to assist with the diagnosis.
Electrocardiogram
The electrocardiogram (ECG or EKG) will help direct what happens acutely in the ER. The EKG measures electrical activity and conduction in heart muscle. In a heart attack in which the full thickness of the heart muscle is involved, the EKG shows characteristic changes that establish the diagnosis of a myocardial infarction. Some heart attacks only involve small parts of the heart muscle; in these cases, the EKG can look relatively normal.


Blood tests
If the EKG does not diagnose a heart attack (an EKG can be normal even in the presence of a heart attack) blood testing may be required to further look for heart damage. When heart muscle becomes irritated it may leak chemicals that can be measured in the blood. Levels of the cardiac enzymes myoglobin, CPK, and troponin are often measured, alone or in combination, to assess whether heart muscle damage has occurred. Unfortunately, it takes time for these chemicals to accumulate in the blood stream after the heart muscle has been insulted. Blood samples need to be drawn at the appropriate time so that the results can be usefully interpreted. For example, the recommendation for the troponin blood test is to draw a first sample at the time the patient arrives in the ER, and then a second sample 6-12 hours later. Usually it requires two negative samples to confirm that no heart muscle damage has occurred. (Please note that under special circumstances, one sample may be sufficient.)

Chest X-ray
A chest X-ray may be taken to look for a variety of findings including the shape of the heart, the width of the aorta, and the clarity of the lung fields.
If a heart attack has been proven not to have occurred, that is a heart attack has been "ruled out," further evaluation of the heart may be undertaken using stress tests, echocardiography, CT scans, or heart catheterization. The decision as to which test(s) to use, needs to be individualized to the patient and his or her specific situation.