Key result
Larger infarct size, measured by a 1,000-unit increase in creatine kinase-MB area under the curve, was significantly associated with higher 90-day mortality (HR 1.09).
Why the study?
Does infarct size quantification using sophisticated curve modeling of serial CK-MB measures predict mortality and clinical outcomes similarly to traditional methods in STEMI patients treated with reperfusion therapy?
Observational (n=1,718)
Yes
Does infarct size quantification using sophisticated curve modeling of serial CK-MB measures predict mortality and clinical outcomes similarly to traditional methods in STEMI patients treated with reperfusion therapy?
Hazard Ratio: 1.09 (95% CI 1.06–1.13)
p-value: p=<0.01
Sophisticated curve modeling of serial CK-MB measures provides comparable prognostic information to traditional methods for predicting 90-day outcomes in STEMI patients, but requires intensive serial sampling.
Alternative CK-MB metrics for infarct size need validation before clinical use; leaves open optimal quantification for STEMI risk assessment.
BACKGROUND: Larger infarct size measured by creatine kinase (CK)-MB release is associated with higher mortality and has been used as an important surrogate endpoint in the evaluation of new treatments for ST-segment elevation myocardial infarction (STEMI). Traditional approaches to quantify infarct size include the observed CK-MB peak and calculated CK-MB area under the curve (AUC). We evaluated alternative approaches to quantifying infarct size using CK-MB values, and the relationship between infarct size and clinical outcomes. METHODS: Of 1,850 STEMI patients treated with reperfusion therapy in the COMplement inhibition in Myocardial infarction treated with Angioplasty (COMMA) (percutaneous coronary intervention (PCI)-treated) and the COMPlement inhibition in myocardial infarction treated with thromboLYtics (COMPLY) (fibrinolytic-treated) trials, 1,718 (92.9%) (COMMA, n = 868; COMPLY, n = 850) had at least five of nine protocol-required CK-MB measures. In addition to traditional methods, curve-fitting techniques were used to determine CK-MB AUC and estimated peak CK-MB. Cox proportional hazards modeling assessed the univariable associations between infarct size and mortality, and the composite of death, heart failure, shock and stroke at 90 days. RESULTS: In COMPLY, CK-MB measures by all methods were significantly associated with higher mortality (hazard ratio range per 1,000 units increase: 1.09 to 1.13; hazard ratio range per 1 standard deviation increase: 1.41 to 1.62; P <0.01 for all analyses). In COMMA, the associations were similar but did not reach statistical significance. For the composite outcome of 90-day death, heart failure, shock and stroke, the associations with all CK-MB measures were statistically significant in both the COMMA and COMPLY trials. CONCLUSIONS: Sophisticated curve modeling is an alternative to infarct-size quantification in STEMI patients, but it provides information similar to that of more traditional methods. Future studies will determine whether the same conclusion applies in circumstances other than STEMI, or to studies with different frequencies and patterns of CK-MB data collection.
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Lópes et al. (2013) conducted an observational in ST-segment elevation myocardial infarction (STEMI) (n=1,718). Creatine kinase-MB (CK-MB) level vs. Lower CK-MB levels was evaluated on 90-day mortality (HR 1.09, 95% CI 1.06 to 1.13, p=<0.01). Larger infarct size, measured by a 1,000-unit increase in creatine kinase-MB area under the curve, was significantly associated with higher 90-day mortality (HR 1.09).
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