Procedure: Symptom-limited (by angina, dyspnea, and/or fatigue) exercise treadmill testing using the Bruce or modified Bruce protocol.
Parameters for score:
(1) duration of exercise in minutes, as a whole number. Different protocols have different completion times (12 minutes in regular Bruce to 27 in modified Bruce). In Figure 1 page 850 in Mark et al (1991) the maximum was 18 minutes. The people with significant disease apparently had exercise times < 3 minutes (Table 2 page 851, Mark et al, 1991).
(2) maximal ST-segment deviation during or after exercise in millimeters, as a whole number
(3) treadmill angina index, according to the following table:
|
Angina During Treadmill Procedure
|
Index
|
|
none
|
0
|
|
nonlimiting
|
1
|
|
exercise-limiting
|
2
|
Duke treadmill exercise score =
= (duration of exercise in minutes) – (5 * ABSOLUTE((maximal ST segment deviation))) – (4 * (treadmill angina index))
Interpretation:
• minimum score: probably around –28 (assumes 0 minute exercise, 4 mm ST segment deviation and angina-limited; see Figure 1 page 850 in Mark et al, 1991).
• maximum score: determined by exercise protocol (no ST segment deviation and no angina)
• The lower the score, the higher the risk for the patient.
|
Score
|
Risk Level
|
|
>= 5
|
low
|
|
>= – 10 to < 5
|
intermediate
|
|
< -10
|
high
|
In Mark et al (1991), the 4 year survival for low risk group was >= 98%, for the intermediate group 92-95%, and 70-80% in the high risk group (Table 3, page 853). Interventions would affect survival.
