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New enzyme thresholds may help determine clinical endpoints of MI after PCI
Matching the 1-year mortality risk for PCI-related MI to the level of risk for spontaneous MI would require elevating creatine kinase-myocardial band thresholds more than three times the upper limit of normal, according to recent study findings.
To compare the prognoses of procedural MI to that of spontaneous MI, researchers used data from patients treated with PCI from the EARLY-ACS and SYNERGY trials.
Among the 9,087 patients who underwent PCI in those trials, there were 773 procedural MIs and 239 spontaneous MIs within the first 30 days. Adjusted HRs for 1-year death were 1.39 (95% CI, 1.01-1.89) for procedural MI and 5.37 (95% CI, 3.90-7.38) for spontaneous MI.
The creatine kinase-myocardial band (CK-MB) threshold for procedural MI that achieved the same prognosis as spontaneous MI was 27.7 times the upper limit of normal (ULN; 95% CI, 13.9-58.4). There were differences between thresholds among patients in the SYNERGY trial (57.9 times the ULN; 95% CI, 17.9- 63.6) and the EARLY-ACS trial (20.4 times the ULN; 95% CI, 5.16-24.2). A conservative estimate based on the lower bound of the 95% CI suggests a threshold of nearly 14 times the ULN of CK-MB may be required to match 1-year mortality risk rates between procedural and spontaneous MI, researchers wrote.
They concluded that although these observations raise important implications for the design and interpretation of trials that use MI as an endpoint, “[T]here is no unique gold standard for defining the relationship of procedural MI with outcome or for ascertaining how that differs from spontaneous MI. Although other approaches can complement ours (eg, maximal discrimination, maximal predictive ability), we believe that the emphasis on prognostic homogeneity can highlight an additional dimension for the definition of this endpoint.”
Disclosure: Leonardi reports no relevant financial disclosures.