Periprocedural PCI Myocardial Biomarker Elevation and Mortality
Is a post-procedural increase in creatine kinase–myocardial band (CK-MB) or cardiac troponin (cTn) associated with high risk of death at 1 year in patients with stable angina undergoing percutaneous coronary intervention (PCI)?
The study was a retrospective analysis of pooled patient-level data from five contemporary coronary stent trials and one large registry, encompassing 13,452 patients. All-cause mortality at 1 year of patients with stable angina with normal baseline biomarkers was compared between patients with and those without rises in cTn and CK-MB with different cutoff values. Survival analysis was stratified by peak biomarker levels using low threshold cut-offs (CK-MB of 5 x upper limit of normal [ULN], cTn of 35 x ULN), and high cut-offs (CK-MB of 10 x ULN, cTn of 70 x ULN). The vast majority of patients underwent drug-eluting stent placement (97%). In total, 11,613 and 10,639 patients, respectively, had CK-MB and cTn measurements. Both biomarkers were measured in 8,859 patients.
The mean age of the pooled cohort was 64 years, 73% were men, 31% were diabetics, and 78% had one-vessel disease. The overall percentage of patients with elevated biomarkers following PCI was 23.9% for CK-MB and 68.4% for cTn. A total of 259 patients (1.9%) died within the first year following PCI. In univariable analyses, patients who had higher levels of CK-MB and cTn had significantly higher mortality. Interestingly, in multivariable analyses, only an increased post-procedural CK-MB ≥10 x ULN (hazard ratio [HR], 3.43; 95% confidence interval [CI], 1.81-6.49) but not cTn ≥70 x ULN (HR, 1.63; 95% CI, 0.88-3.00) was associated with increased risk of death.
The authors concluded that post-PCI rises in CK-MB but not cTn are associated with a higher risk of death at 1 year.
The findings of the study are difficult to interpret. The retrospective nature of the study lends a high risk of selection bias, given biomarkers were not systematically measured in all patients and were available for two-thirds of patients. Important unaccounted for confounders include the time from PCI in which these biomarkers were measured, the indication for their measurements, and the occurrence of procedural complications. Practically, CK-MB is only seldom measured, and most core laboratories no longer perform the assay routines. Overall, while interesting, the study findings have little implications for clinical practice.
Keywords: Angina, Stable, Biological Markers, Creatine Kinase, MB Form, Drug-Eluting Stents, Myocardium, Percutaneous Coronary Intervention, Risk, Troponin
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