Myocardial infarction: a clinical prediction rule can predict mortality in patients who receive reperfusion therapy

Clinical bottom line (level 1a)

  1. One in sixteen patients with a myocardial infarction who received reperfusion therapy died.
  2. A clinical prediction rule can usefully rank patients who receive reperfusion therapy at high or low risk of death.
  3. One in six patients with a myocardial infarction who did not receive reperfusion therapy died.
  4. A clinical prediction rule can usefully identify patients who do not receive reperfusion therapy at low risk for death, but cannot accurately identify high risk patients.
Morrow et al: JAMA 2001; 286 ( 11 ): 1356-1359
Expires April 2004

The study

Inception cohort study with objective outcomes, adjusted for confounding factors, validated in an independent set of patients.

Setting: 1529 acute hospitals, USA

84029 patients (aged mean 69, 60% male) with an acute myocardial infarction (chest pain and ST-elevation or new LBBB)

Excluded if
  • died in hospital
  • developed cardiogenic shock
Validation of a clinical prediction rule (TIMI Risk score). Sum the points for following clinical features found at presentation
  • aged 75 or more: 3
  • aged 65-74: 2
  • history of diabetes, hypertension or angina: 1
  • systolic bp < 100 mmHg: 3
  • heart rate > 100 beats/min: 2
  • Killip class II-IV (evidence of heart failure): 2
  • weight < 67 kg: 1
  • anterior ST elevation or left bundle-branch block: 1
  • time to reperfusion therapy > 4 hours: 1

Outcomes studied:
  • inhospital mortality
  • no reperfusion therapy: inhospital mortality
  • reperfusion therapy: death

    The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)    		 NNF
    (95% CI)
    inhospital mortality - days 10612/84029 13%
    (12% to 13%)    		 8
    (8 to 8)
    no reperfusion therapy: inhospital mortality - days 8064/43815 18%
    (18% to 19%)    		 5
    (5 to 6)
    reperfusion therapy: death - days 2523/40214 6.3%
    (6.0% to 6.5%)    		 16
    (15 to 17)
     

    No reperfusion therapy given

    prediction death at days life at days LR
    (95% CI)    		 probability of death at days
    > 8 1781 4362 1.8
    (1.7 to 1.9)     		29%
    8 1113 3340 1.5
    (1.4 to 1.6)     		25%
    7 1271 4024 1.4
    (1.3 to 1.5)     		24%
    6 1294 4587 1.3
    (1.2 to 1.3)     		22%
    5 1140 4860 1.0
    (0.98 to 1.1)     		19%
    4 808 4963 0.72
    (0.67 to 0.77)     		14%
    3 359 3231 0.49
    (0.44 to 0.55)     		10%
    2 169 2310 0.32
    (0.28 to 0.38)     		7%
    1 103 2842 0.16
    (0.13 to 0.20)     		3%
    0 26 1232 0.094
    (0.063 to 0.14)     		2%
    total 8064 35751
     

    Reperfusion therapy given

    prediction death at days life at days LR
    (95% CI)    		 probability of death at days
    > 8 355 660 8.0
    (7.1 to 9.1)     		35%
    8 233 778 4.5
    (3.9 to 5.2)     		23%
    7 318 1447 3.3
    (2.9 to 3.7)     		18%
    6 417 2364 2.6
    (2.4 to 2.9)     		15%
    5 426 3835 1.7
    (1.5 to 1.8)     		10%
    4 328 5422 0.90
    (0.815 to 1.0)     		6%
    3 212 5527 0.57
    (0.50 to 0.65)     		4%
    2 137 6086 0.34
    (0.29 to 0.40)     		2%
    1 69 7561 0.14
    (0.11 to 0.17)     		0.9%
    0 28 4011 0.10
    (0.072 to 0.15)     		0.7%
    total 2523 39014
     

      Citation

      1. Morrow DA, Antman EM, Parsons L, et al: application of the TIMI Risk Score for ST-elevation in the National Registry of Myocardial Infarction 3. JAMA 2001; 286 ( 11 ): 1356-1359
      Search Terms: from ACP Journal Club
      Contributor: Chris Ball, April 2002
      Reviewer:

      Clinical Question.
      Patient myocardial infarction
      Intervention or Exposure clinical features and ECG on presentation
      Outcome death