Myoglobin levels at 12 hours identify patients at low risk for 30-day mortality after thrombolysis in acute myocardial infarction: a Thrombolysis in Myocardial Infarction 10B substudy.
OBJECTIVE
We sought to identify, by use of serum cardiac markers, patients at low risk for 30-day mortality after ST-segment elevation myocardial infarction.


BACKGROUND
Baseline cardiac markers are currently used to identify patients at increased risk for short-term events. We hypothesized that serum markers measured after treatment could identify patients at low risk for 30-day mortality.


METHODS
A total of 839 patients from the Thrombolysis in Myocardial Infarction (TIMI) 10B study had myoglobin, cardiac-specific troponin-I, creatine kinase (CK)-MB measurements at the following time points; baseline, 90 minutes, and 3 and 12 hours after thrombolysis. By use of receiver operating characteristic analysis, thresholds were derived to predict 30-day mortality with at least 95% negative predictive value.


RESULTS
Ninety minutes after thrombolysis myoglobin was superior to troponin-I or CK-MB in identifying patients at low risk for mortality. The 30-day mortality for 12-hour myoglobin < or = 239 ng/mL was 1.4% compared with 9.1% for levels > 239 ng/mL (P < .001). For 12-hour troponin-I (threshold 81.5 ng/mL), mortality was 1.9% versus 6.6% (P = .001) if above threshold; similarly for CK-MB at 12 hours (threshold 191 ng/mL) it was 3.3% versus 7.9% (P = .02). Multivariate analysis of baseline and posttreatment cardiac markers, age, sex, infarct artery location, and 90-minute TIMI flow grade identified only 12-hour myoglobin among the cardiac markers as independently predicting a low 30-day mortality (odds ratio 0.11, 95% confidence interval 0.02-0.50, P < .004).


CONCLUSIONS
Serum cardiac markers can identify greater than two thirds of patients at low risk for 30-day mortality. A low 12-hour myoglobin level (< or = 239 ng/mL in this substudy) identifies such patients at low risk and could potentially assist in early risk stratification and triage after ST-segment elevation myocardial infarction.
Srinivas
V S
VS
Division of Cardiology, Department of Medicine, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, NY, USA.
Cannon
C P
CP
Gibson
C M
CM
Antman
E M
EM
Greenberg
M A
MA
Tanasijevic
M J
MJ
Murphy
S
S
de Lemos
J A
JA
Sokol
S
S
Braunwald
E
E
Mueller
H S
HS
D000368:Aged; D015415:Biomarkers / Q000097:blood; D016009:Chi-Square Distribution; D003402:Creatine Kinase / Q000097:blood; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood* / Q000188:drug therapy* / Q000201:enzymology / Q000401:mortality*; D009211:Myoglobin / Q000097:blood*; D012372:ROC Curve; D018570:Risk Assessment / Q000379:methods; D015912:Thrombolytic Therapy; D016896:Treatment Outcome; D019210:Troponin I / Q000097:blood
D015415:Biomarkers; D009211:Myoglobin; D019210:Troponin I; D003402:Creatine Kinase