Chronic stable angina assessing the pretest probability of coronary artery disease


 * Associate Editor-in-Chief: Smita Kohli, M.D.

Overview
Pretest probability is defined as the probability of the target disorder before the result of a diagnostic test is known. A number of studies have emphasized the importance of pretest probability of coronary artery disease (CAD). Once a thorough patient history and physical examination is complete, it is important to assess the probability of underlying CAD, as this helps both the physician and the patient to determine the next step in the diagnosis and treatment. In patients with chronic stable angina, the strongest predictors contributing to underlying significant CAD include: the age, gender and type of pain (typical, atypical) experienced.

Pretest Probability

 * Pretest probability is defined as the probability of the target disorder before the result of a diagnostic test is known.
 * The pretest probability is especially useful for:
 * Deciding whether it is worth proceeding with testing at all (this is referred to as the test threshold)
 * Selecting the type of diagnostic test
 * Interpreting the results of a diagnostic test
 * Choosing whether to start therapy: a)without further testing (this is referred to as the treatment threshold) or b)while awaiting further testing

Calculating the pretest probability for coronary artery disease

 * The first step is to categorize the nature of the chest pain or discomfort. This can be done as follows:
 * Typical angina(definite): The characteristics of typical angina include:
 * Substernal chest discomfort of characteristic quality and duration
 * The pain is provoked by exercise or emotional stress
 * The pain is relieved by rest or NTG
 * Atypical angina(probable): Meets two of the above criteria
 * Non-anginal pain: Meets one or zero of the anginal characteristics.


 * Based on the ACC/AHA 2002 guidelines, the pretest probability can be classified into:
 * Low probability: less than 10%-20%;
 * Intermediate probability: between 20%-80%;
 * High probability: more than 80%-90%.


 * A quick way to assess this is shown in Table 1.

Table 1: Pretest Probability of Coronary Artery Disease

Vote on and Suggest Revisions to the Current Guidelines

 * The Chronic Stable Angina Living Guidelines: Vote on current recommendations and suggest revisions to the guidelines