The risk of mortality within 30 days after an acute myocardial infarction with or without treatment with a thrombolytic agent can be estimated using a predictive instrument developed by Selker et al..
Parameters:
(1) patient age
(2) systolic blood pressure
(3) history of diabetes
(4) heart rate
(5) ST segment elevation, with size of the acute myocardial infarction
(6) Q waves without ST segment elevation in inferior acute myocardial infarction
(7) location of the acute myocardial infarction
(8) right bundle branch block
(9) time of symptom onset to emergency department ECG
(10) impact of use of thrombolytic therapy
|
Parameter |
Finding |
Points |
|
patient age (1) |
< 40 years |
40 |
|
|
40 to < 75 years |
age |
|
|
>= 75 |
75 |
|
systolic blood pressure (2) |
< 60 mm Hg |
60 |
|
|
60 to < 190 mm Hg |
systolic blood pressure |
|
|
>= 190 mm Hg |
190 |
|
history of diabetes (3) |
absent |
0 |
|
|
present |
1 |
|
heart rate (4) |
< 70 beats per minute |
0 |
|
|
70 to < 120 beats/minute |
(heart rate) - 70 |
|
|
>= 120 beats/minute |
50 |
|
Q waves without ST segment elevation(6) |
< 2 contiguous leads in inferior region |
0 |
|
|
2 contiguous leads |
2 |
|
|
3 contiguous leads |
3 |
|
|
>= 4 contiguous leads |
4 |
|
location of acute MI (7) |
anterior, with >= 2 contiguous leads in V1-V4 with ST segment elevation |
1 |
|
|
posterior, with >= 2 contiguous leads with ST segment elevation in both inferior (II, III, aVF) and lateral (V5, V6, I, aVL) |
1 |
|
|
posterior without the contiguous leads |
1 |
|
|
all others |
0 |
|
right bundle branch block (8) |
absent |
0 |
|
|
present |
1 |
|
time from symptom onset (9) |
thrombolytic therapy given |
6.25 |
|
|
no thrombolytics, and time from onset to ECG >= 0 and < 1 hour |
(time from onset to ECG) |
|
|
no thrombolytics, and time from onset to ECG >= 1 and < 2 hours |
(2 * (time from onset to ECG)) – 1.00 |
|
|
no thrombolytics, and time from onset to ECG >= 2 and < 3 hours |
(1.50 * (time from onset to ECG)) |
|
|
no thrombolytics, and time from onset to ECG >= 3 and < 4 hours |
(0.75 * (time from onset to ECG)) + 2.25 |
|
|
no thrombolytics, and time from onset to ECG >= 4 hours and < 8 hours |
(0.25 * (time from onset to ECG)) + 4.25 |
|
|
no thrombolytics, and time from onset to ECG >= 8 hours |
6.25 |
|
impact of thrombolytic use (10) |
no thrombolytic therapy |
0 |
|
|
thrombolytic therapy given < 8 hours after onset |
(1 – ((number of hours after onset to therapy) / 9)) * (earliness index) |
|
|
thrombolytic therapy given >= 8 hours after onset |
(1/9) * (earliness index) |
where:
• All location-specific ECG-based variables are based on having 2 contiguous leads in a region, with 1 lead having an ST segment elevation >= 1 mm and 1 lead having an ST segment elevation >= 0.5 mm
• For time from symptom onset and impact of thrombolytic use, a time from onset > 8 hours is set to 8.
• The earliness index is the percentage of leads with early ECG characteristics for acute myocardial infarction.
• If a thrombolytic agent was not given, then need to make an assumption for the impact of thrombolytic use (10) if comparing mortality with and without thrombolytic therapy. I will assume that the time to ECG in the ED is the time that would be used if thrombolytic had been given.
|
ST segment elevation for size of acute MI (5) |
Points |
|
>= 2 contiguous leads in V1 to V4 with ST segment elevation (anterior MI) |
MIN(25, ((number of contiguous leads in V1 to V6 with ST segment elevation) + (sum of the ST segment elevation in the contiguous leads))) |
|
posterior MI AND < 2 contiguous leads in V1 to V4 with ST segment elevation |
MIN(25, ((number of contiguous leads in V5, V6, I, aVL, II, III, aVF with ST segment elevation) + (sum of the contiguous ST segment elevation in V5, V6, I, aVL, II, III, aVF) + (number of leads V1 to V3 with ST segment depression of 0.5 mm or more) + (absolute value (sum of ST segment depression of 0.5 mm or more in leads V1 to V3)))) |
|
not posterior MI AND < 2 contiguous leads in V1 to V4 with ST segment elevation |
MIN(25, ((number of contiguous leads in V5, V6, I, aVL, II, III, aVF with ST segment elevation) + (sum of the ST segment elevation in V5, V6, I, aVL, II, III, aVF))) |
where:
• The sum of ST segment elevation in the first and second group is specified as contiguous, while the third is not specified as contiguous.
• If the value for the ST segment elevation is > 25, then the value is set to 25.
earliness index =
= MAX(0.25, ((number of contiguous leads with ST segment elevation and tall T waves) + (0.5 * (number of contiguous leads with ST wave elevation but without abnormal Q waves or tall T waves))) / (number of contiguous leads with ST segment elevation))
where:
• The value for an earliness index < 0.25 is set to 0.25.
|
ECG Lead |
Threshold for "tall" T wave amplitude |
|
V1 |
3.5 mm |
|
V2 |
10.0 mm |
|
V3 |
10.0 mm |
|
V4 |
10.0 mm |
|
V5 |
6.0 mm |
|
V6 |
4.0 mm |
|
I |
2.5 mm |
|
aVL |
2.5 mm |
SpecialtyICD-10InfoSpecialty: Cardiology ICD-10: , |
