Schroder et al developed a model for predicting mortality risk in a patient with an acute myocardial infarction (AMI) based on changes in the electrocardiogram (ECG) seen at 90 minutes after thrombolysis. The authors are from the Reha-Klinik Ahrenshoop, University of Hamburg, Klinikum Lippe-Selmold and Universitatsklinikum Benjamin Franklin in Germany.
Method of ECG analysis:
(1) PR segment used as reference baseline
(2) lens-intensified calipers used for reading
(3) ST segment deviation read to the nearest 0.025 mV (0.25 mm) at 20 milliseconds after the end of the QRS complex
Parameters:
(1) location of myocardial infarction (anterior or inferior only)
(2) maximum ST wave deviation in location-specific leads before thrombolysis
(3) maximum ST wave deviation in location-specific leads 90 minutes after thrombolysis
(4) presence of bundle branch block (BBB)
|
Infarct Location |
Leads Observed |
Measure |
|
anterior |
(8): I, aVL, V1, V2, V3, V4, V5, V6 |
maximum elevation |
|
anterior |
(3): II, III, aVF |
maximum depression |
|
inferior |
(5): II, III, aVF, V5, V6 |
maximum elevation |
|
inferior |
(4): V1, V2, V3, V4 |
maximum depression |
For an anterior MI, the infarct is termed large if the baseline ST segment elevation is > 4.5 mm, else it is termed small.
where:
• 1 mm = 0.1 mV
|
Infarct |
ECG findings |
Risk Group |
|
anterior, small |
maximum ST segment elevation <= 1.0 mm |
low risk |
|
|
maximum ST segment elevation 1.1 - 5.0 mm |
medium risk |
|
|
maximum ST segment elevation > 5.0 mm |
high risk |
|
|
bundle branch block |
high risk |
|
anterior, large |
maximum ST segment elevation <= 2.0 mm |
low risk |
|
|
maximum ST segment elevation 2.1 - 3.0 mm |
medium risk |
|
|
maximum ST segment elevation > 3.0 mm |
high risk |
|
|
bundle branch block |
high risk |
|
inferior |
maximum ST segment deviation <= 1 mm without bundle branch block |
low risk |
|
|
maximum ST segment deviation <= 1 mm with bundle branch block |
medium risk |
|
|
maximum ST segment deviation 1.1 - 2.0 mm with or without bundle branch block |
medium risk |
|
|
maximum ST segment deviation > 2 mm with or without bundle branch block |
high risk |
from Figure 1, page 1480
where:
• Deviation refers to either elevation or depression.
|
|
probability 30 day cardiac mortality |
|
Location AMI |
low risk |
medium risk |
high risk |
|
anterior |
0.9% |
4.1% |
15.2% |
|
inferior |
1.1% |
4.0% |
10.3% |
from Table 3, page 1482
|
Risk Group |
180 day mortality (all cause) |
|
low |
3.1% |
|
medium |
7.1% |
|
high |
16.2% |
from Table 3, page 1482
Specialty: Cardiology
ICD-10: ,
