Troponin I levels and postoperative myocardial infarction following renal transplantation

BACKGROUND

The relationship of routine postoperative troponin I (TnI) monitoring in kidney transplant recipients and in-hospital myocardial infarction (MI) is not known.

METHODS

This observational study evaluated the prevalence of abnormal postoperative TnI (Ortho Clinical Diagnostics assay) in 376 consecutive kidney or kidney/pancreas transplant recipients. In-hospital MI was adjudicated using the universal definition. Rates of death and coronary revascularizations at 1 year were studied. Logistic regression analysis was performed to identify independent predictors of abnormal TnI.

RESULTS

Ninety-five (25%) recipients had abnormal TnI (>0.04 ng/ml) following transplantation. Abnormal TnI levels were more common in older (mean age: 52.2 ± 13.4 vs. 48.3 ± 13.2 years, p = 0.01), diabetic (57.9 vs. 45.6%, p = 0.04), and prior coronary artery disease (31.6 vs. 20.3%, p = 0.02) patients. In-hospital MI occurred in 6 patients (1.6%). All subsequent in-hospital cardiovascular events occurred in the abnormal postoperative TnI group; most in those with TnI levels >1 ng/ml. Previous coronary artery disease was the only independent predictor of a postoperative TnI level >1 ng/ml in multivariate analysis (odds ratio 4.61, 95% confidence interval 1.49-14.32). At 1 year there was no significant difference in death (3.2 vs. 1.8%, p = 0.42) and borderline significant difference in coronary revascularization (5.3 vs. 1.4%, p = 0.049) in abnormal versus normal TnI groups.

CONCLUSIONS

In-hospital MI was infrequent, but abnormal TnI highly prevalent following renal transplantation. Normal TnI levels following renal transplantation had a high negative predictive value in excluding patients likely to develop subsequent postoperative MI. The role of a higher TnI cut-off for screening for postoperative MI in high-risk subgroups deserves future prospective evaluation.

Relationship between carotid artery stiffness index, BNP and high-sensitivity CRP

Arterial stiffness is an independent predictor of cardiovascular morbidity and mortality. Brain natriuretic peptide (BNP) and high-sensitivity C-reactive protein (hs-CRP) are considered as novel biomarkers that are useful in the prediction of early cardiovascular risk. We studied the relationship between carotid artery stiffness index beta and the cardiovascular biomarkers BNP and hs-CRP in 55 consecutive subjects. Carotid artery stiffness was assessed using the stiffness index beta derived from brachial artery blood pressure measurement and carotid ultrasonography. Venous blood samples were obtained for BNP and hs-CRP. Pearson's correlation coefficient suggested a strong bivariate relationship between carotid stiffness index beta and age (r=0.56, P<0.0001), BNP (r=0.45, P<0.004) and hs-CRP (r=0.26, P=0.06), respectively. On multiple regression analysis, significant correlations were found between carotid stiffness index beta and age (P=0.004), BNP (P=0.027) and hs-CRP (P=0.029). These findings suggest that there is a relationship between intra-cardiac pressures (measured by BNP), vascular inflammation (measured by hs-CRP) and vascular stiffness. Cardiovascular biomarkers are thus associated with functional parameters of the vascular tree.