Description

Madsen et al developed a risk calculation in 1983 to determine the probability of an adverse cardiac event occurring for a patient with a recent myocardial infarct. At that time patients with myocardial infarcts were hospitalized for relatively long periods. It was felt that patients at low risk for an adverse cardiac event could be discharged earlier. Patients may be evaluated from day 5 to 30 after the infarct, with the endpoint being the probability of an adverse cardiac event in the next 2 weeks.

Parameters studied using a Cox regression model:

(1) age

(2) history of previous myocardial infarction

(3) heart failure

(4) ventricular fibrillation

(5) asystole

(6) supraventricular tachycardia

(7) premature ventricular beats

(8) nodal rhythm

(9) extension of the myocardial infarct

Parameter

Finding

Points

age in years

(age)

history of previous myocardial infarction

present

1

absent

0

heart failure

present

1

absent

0

ventricular fibrillation

present

1

absent

0

asystole, with or without ventricular fibrillation

present

1

absent

0

supraventricular tachycardia

present

1

absent

0

premature ventricular beats

present

1

absent

0

nodal rhythm

present

1

absent

0

extension of myocardial infarct

present

1

absent

0

score for cardiac arrest endpoint =

= (0.010 * (points for age)) + (2.2 * (points for heart failure)) + (points for supraventricular tachycardia) + (0.9 * (points for premature ventricular beats)) + (points for extension of MI) - 0.6

score for death endpoint =

= (0.082 * (points for age)) + (2.3 * (points for heart failure)) + (2.7 * (points for ventricular fibrillation)) + (3.4 * (points for asystole)) - 4.9

score for cardiogenic shock endpoint =

= (0.028 * (points for age)) + (0.22 * (points for previous MI)) + (3.3 * (points for heart failure)) + (1.2 * (points for ventricular fibrillation)) + (1.2 * (points for asystole)) + (0.8 * (points for nodal rhythm)) - 1.7

X =

= ((hazard for cardiac arrest on starting date) * EXP(score for cardiac arrest)) + ((hazard for death on starting date) * EXP(score for death)) + ((hazard for cardiogenic on starting date) * EXP(score for cardiogenic shock))

risk of an adverse cardiac event within 14 days =

= 1 - EXP((-1) * (X))

day

hazard for cardiac arrest

hazard for death

hazard for cardiogenic shock

5

0.00687

0.00142

0.001

6

0.00656

0.00133

0.00089

7

0.00595

0.0012

0.00075

8

0.00518

0.0011

0.00062

9

0.00433

0.00089

0.00059

10

0.00439

0.0008

0.00053

11

0.00423

0.00075

0.00052

12

0.0041

0.00084

0.00043

13

0.00338

0.00092

0.00044

14

0.00331

0.00095

0.00041

15

0.00325

0.00092

0.0004

16

0.00284

0.00085

0.00033

17

0.00216

0.00074

0.0003

18

0.00187

0.00074

0.00033

19

0.00141

0.00057

0.0003

20

0.00136

0.00057

0.0003

21

0.00136

0.00057

0.00026

22

0.00136

0.00052

0.00026

23

0.00136

0.00054

0.00021

24

0.00107

0.00054

0.00021

25

0.001

0.00057

0.00021

26

0.00134

0.00066

0.00021

27

0.00151

0.00072

0.00021

28

0.00154

0.0007

0.00021

29

0.00141

0.00056

0.00021

30

0.00154

0.00059

0.00021

(data from Figure 1, page 12)

Interpretation:

• If the risk of an adverse cardiac event was less than 2%, then the authors felt the patient could be discharged.

Limitation:

• The score was formulated in 1983, before many advances in the diagnosis and management of myocardial infarction. However, the risk estimate may be useful in areas where the newest techniques are not available.