Myocardial infarction: worsening Killip class and increasing age increased the risk of dying.

Clinical bottom line (level 1b)

  1. One in fourteen patients with a myocardial infarction were dead within 30 days.
  2. The risk of dying was increased with
    • worsening Killip class
    • increasing age
    • cardiovascular risk factors
    • an anterior MI
Lee et al: Circulation 1995; 91 (6): 1659-1668
Expires March 2003

The study

Inception cohort study with objective outcomes, adjusted for confounding factors, not validated in an independent set of patients.

Setting: multicentre

41021 patients (aged mean 62, 75% male) with acute myocardial infarction presenting with ST-segment elevation (within 6 hours of symptom onset)

Excluded if
  • previous treatment with streptokinase or anistreplase
  • non-compressible venous punctures
  • history of stroke
  • active or recent bleeding history or major coagulation abnormality
  • recent trauma or major surgery



Factors studied:
  • cardiovascular risk factors, other history, presenting characteristics, Killip class
  • Killip class IV v. I
  • Killip class III v. I
  • increasing age (>70 v. < 52)


Patients received streptokinase, tPA or a combination.

Multivariate logistic regression analysis performed to adjust for confounding factors.

99.5% followed for 30 days
Outcomes studied:
  • death

The evidence

outcome time to outcome number of patients/total number %
(95% CI)		 NNF
(95% CI)
death 30 days 2851/41021 7.0%
(6.7% to 7.2%)		 14
(14 to 15)

prognostic factor for
death 		time to outcome control rate (%) adjusted OR
(95% CI)		 NNF+
(95% CI)
Killip class IV v. I 30 days /
(5.1%) 		7.86
(5.88 to 10.49) 		4
(3 to 5)
Killip class III v. I 30 days /
(5.1%) 		4.37
(3.34 to 5.71) 		7
(5 to 10)
increasing age (>70 v. < 52) 30 days /
(%) 		3.88
(3.52 to 4.28)
( to )

  • The following factors were independently associated with increased mortality
    • increased heart rate
    • hypotension
    • anterior myocardial infarction
    • diabetes mellitus
    • smoking
    • history of hypertension
    • history of cerebrovascular disease
    • previous CABG

Comments

  1. Patients were enrolled in a randomised controlled trial comparing different thrombolytic regimens.
  2. Odds ratios were presented graphically - only the largest (OR > 2.5) were reported in the text.
  3. Killip class
    • I: no heart failure (85%)
    • II: crackles, S3 gallop, elevated venous pressure (13%)
    • III: frank pulmonary oedema (1%)
    • IV: cardiogenic shock - hypotension (systolic bp < 90 mmHg) and evidence of hypoperfusion (oliguria, cyanosis, sweating) (1%)

Citation

  1. Lee KL, Woodlief LH, Topol EJ, et al: Predictors of 30-day mortality in the era of reperfusion for acute myocardial infarction: results from an international trial of 41 021 patients. Circulation 1995; 91 (6): 1659-1668
    Search Terms:
    Contributor: Chris Ball and Clare Wotton, February 2000
    Reviewer:

    Clinical Question.
    Patient myocardial infarction
    Intervention or Exposure age, Killip class, cardiovascular risk factors
    Outcome death