Chest pain: CK-MBmasswas the best test for diagnosing MI, and ruled it out if negative at 20 hours.

Clinical bottom line (level 4)

  1. CK-MB mass was the best test to diagnose acute MI (absolute SpPin).
  2. The best test to rule out acute MI at 3 hours was myoglobin, but further tests are needed in any patients not considered low risk.
  3. The best test to rule out acute MI at 20 hours was CK-MB mass .
  4. Physicians were good at predicting which patients are at high risk for acute MI, but were less good at excluding it.
de Winter et al: Circulation 1995; 92: 3401-3407
Expires July 2003

The study

Setting: emergency department, two teaching hospitals, Holland

309 patients (aged mean 64 years, 66% male) chest pain suggestive of myocardial ischaemia for <12 hours

Excluded if
  • refusal or inability to give informed consent
  • severe skeletal muscular damage
  • trauma
  • cardiac resuscitation
  • inability to withdraw blood from the cannula
  • incorrect or incomplete data collection

Independent ?blinded reference standard, applied in all patients from a consecutive appropriate spectrum.
Reference standard:
  • review at discharge of history, ECG abnormalities and a typical rise and fall in serum CK-MBact curve with a peak exceeding 8 U/l
Diagnostic test: routine blood samples drawn through indwelling venous catheter and sent for:
  • myoglobin (>90 ng/ml = positive)
  • troponin-T (>0.1 ng/ml = positive)
  • CK-MBmass (8.0 ng/ml = positive)
at 3, 4, 5, 6, 7, 8, 12, 16,20, 24 hours after the onset of symptoms (determined by asking patients or relatives)

The evidence

pre-test probability of acute MI: 53%, (95% CI: 47% to 58%)

diagnostic test LR+
(95% CI)		 post-test probability LR-
(95% CI)		 post-test probability
positive CK-MBact- 3 hours after symptom onset inf
(8.9 to inf) 		100% 0.82
(0.76 to 0.89) 		47%
positive CK-MBact- 4 hours after symptom onset 27
(17 to 41) 		97% 0.74
(0.67 to 0.81) 		44%
positive CK-MBact- 6 hours after 59
(38 to 91) 		98% 0.41
(0.36 to 0.48) 		31%
positive CK-MBact- 8 hours after 81
(56 to 120) 		99% 0.19
(0.16 to 0.23) 		17%
positive CK-MBact- 12 hours after 88
(65 to 120) 		99% 0.12
(0.10 to 0.14) 		12%
positive CK-MBact- 20 hours after inf
(45 to inf) 		100% 0.09
(0.08 to 0.11) 		9%
total 164 145


diagnostic test MI no MI LR+
(95% CI)		 post-test probability LR-
(95% CI)		 post-test probability
positive CK-MBmass- 3 hours after symptom onset inf
(16 to inf) 		100% 0.68
(0.61 to 0.75) 		43%
positive CK-MBmass- 4 hours after 28
(19 to 42) 		97% 0.45
(0.39 to 0.52) 		33%
positive CK-MBmass- 6 hours after 29
(19 to 44) 		97% 0.13
(0.11 to 0.16) 		13%
positive CK-MBmass- 8 hours after 19
(13 to 27) 		95% 0.063
(0.053 to 0.076) 		7%
positive CK-MBmass- 12 hours after 14
(11 to 18) 		94% 0.032
(0.027 to 0.039) 		3%
positive CK-MBmass- 20 hours after 11
(8 to 16) 		92% 0.0
(0.0 to 0.020) 		0%
total 164 145


diagnostic test MI no MI LR+
(95% CI)		 post-test probability LR-
(95% CI)		 post-test probability
myoglobin- 3 hours after symptom onset 34
(23 to 49) 		97% 0.33
(0.28 to 0.38) 		27%
myoglobin- 4 hours after 26
(17 to 38) 		97% 0.24
(0.20 to 0.28) 		21%
myoglobin- 6 hours after 26
(17 to 39) 		97% 0.23
(0.19 to 0.27) 		20%
myoglobin- 8 hours after 25
(17 to 36) 		97% 0.26
(0.22 to 0.30) 		22%
myoglobin- 12 hours after 23
(16 to 31) 		96% 0.33
(0.28 to 0.39) 		27%
myoglobin- 20 hours after 13
(8 to 20) 		94% 0.63
(0.56 to 0.71) 		41%
total 164 145


diagnostic test MI no MI LR+
(95% CI)		 post-test probability LR-
(95% CI)		 post-test probability
positive troponin T- 3 hours after symptom onset 6
(4 to 9) 		87% 0.67
(0.59 to 0.76) 		43%
positive troponin T- 4 hours after 11
(7 to 16) 		92% 0.59
(0.52 to 0.67) 		40%
positive troponin T- 6 hours after 7
(4 to 10) 		89% 0.37
(0.31 to 0.43) 		29%
positive troponin T- 8 hours after 9
(6 to 13) 		91% 0.23
(0.19 to 0.27) 		21%
positive troponin T- 12 hours after 9
(7 to 12) 		91% 0.078
(0.064 to 0.094) 		8%
positive troponin T- 20 hours after 9
(6 to 13) 		91% 0.022
(0.019 to 0.027) 		2%
total 164 145


diagnostic test MI no MI LR
(95% CI)		 post-test probability
physician's prediction of acute MI >75% 95 7 12
(5.8 to 25) 		93%
physician's prediction of acute MI 50%-75% 47 35 1.2
(0.83 to 1.8) 		57%
physician's prediction of acute MI 25%-50% 18 86 0.19
(0.12 to 0.30) 		17%
physician's prediction <25% 3 18 0.15
(0.04 to 0.50) 		14%
total

Comments

  1. Unclear how reference standard was performed- ?by experts (?individual vs. committee).
  2. Note CK-MBact likelihood ratios appear best because it is also used in the reference standard, ie. not independent.
  3. Study indicates that in patients with chest pain who have >7% risk of MI (see Goldman criteria), normal initial cardiac enzymes cannot rule out an MI. COnsequently these patients should not be discharged.

Citation

  1. de Winter RJ, et al: Value of myoglobin, troponin T and CK-MB (mass) in ruling out an acute myocardial infarction in the emergency room. Circulation 1995; 92: 3401-3407
Contributor: Nick Shenker and Chris Ball, July 2000
Reviewer:

Clinical Question.
Patient chest pain
Intervention or Exposure CK-MBmass
Outcome diagnosis of MI