Chronic stable angina risk assessment in patients with an intermediate or high probability of coronary artery disease


 * Associate Editor-in-Chief: Lakshmi Gopalakrishnan, M.B.B.S.

Overview
Based on the ACC/AHA guidelines, the pretest probability of underlying coronary artery disease (CAD) can be classified into low (less than 10%-20%) , intermediate (between 20%-80%) and high probability (more than 80%-90%). All patients with intermediate to high probability of CAD need to undergo exercise stress testing to stratify the risk of subsequent coronary events and hence determine the appropriate diagnostic and therapeutic interventions. Bruce protocol and DUKE score are widely adopted methods for exercise stress testing. The exercise capacity, clinical, hemodynamic and electrocardiographic responses must be considered while interpreting the results of exercise treadmill test.

Exercise Treadmill Test Interpretation

 * Angina: if occurred during or after exercise, particularly if it forces to stop the test.
 * ST segment changes if occurred during or after exercise. Factors that indicate high probability of underlying CAD include:
 * positive J point,
 * Horizontal ST segment depression of less than or equal to 2mm,
 * Downsloping of ST segment depression,
 * Early positive response within 6-minutes,
 * Persistence of ST segment depression for more than 6-minutes into recovery,
 * ST segment depression in five or more leads,
 * Exertional hypotension.


 * Hemodynamic responses like changes in heart rate or blood pressure with exercise,
 * Workload in metabolic equivalents (METs).
 * In a 40-year old man weighing 70kg, 1 MET refers to the resting volume oxygen consumption per minute (VO2).
 * 1 MET = 3.5 mL/min/kg of body weight.

Methods to assess Exercise Treadmill Test

 * Bruce protocol:
 * Bruce protocol is most widely used and has seven stages, with a complete 21-minute exercise and each stage lasting for 2-minutes.
 * The result is satisfactory when a patient completes of 9-12minutes of exercise or 85% of the maximum predicted changes in heart rate


 * DUKE treadmill score = [(exercise duration in minutes) - (5 x ST segment deviation, during or after exercise, in millimeters) - (4 if angina occurs or 8 if angina is the reason to stop the test)]

==ACC/AHA Guidelines- Risk Assessment and Prognosis in Patients With an Intermediate or High Probability of CAD (DO NOT EDIT) == {{cquote|

Class I
1. Patients undergoing initial evaluation. (Exceptions are listed below in classes IIb and III) (Level of Evidence: B)

2. Patients after a significant change in cardiac symptoms. (Level of Evidence: C)

Class IIb
1. Patients with the following ECG abnormalities:
 * a. Preexcitation (Wolff-Parkinson-White syndrome). (Level of Evidence: B)
 * b. Electronically paced ventricular rhythm. (Level of Evidence: B)
 * c. More than 1 mm of rest ST segment depression. (Level of Evidence: B)
 * d. Complete left bundle-branch block. (Level of Evidence: B)

2. Patients who have undergone cardiac catheterization to identify ischemia in the distribution of a coronary lesion of borderline severity. (Level of Evidence: C)

3. Post-revascularization patients who have a significant change in anginal pattern suggesting ischemia. (Level of Evidence: C)

Class III
1. Patients with severe comorbidity likely to limit life expectancy or prevent revascularization. (Level of Evidence: C)}}

Related Chapters

 * T Wave Alternans for Risk Stratification during Exercise Stress Testing

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

Guidelines Resources

 * The ACC/AHA/ACP–ASIM Guidelines for the Management of Patients With Chronic Stable Angina


 * Guidelines on the management of stable angina pectoris: The Task Force on the Management of Stable Angina Pectoris of the European Society of Cardiology


 * ACC/AHA 2002 Guideline Update for the Management of Patients With Chronic Stable Angina


 * The 2007 Chronic Angina Focused Update of the ACC/AHA 2002 Guidelines for the Management of Patients With Chronic Stable Angina