High-Sensitivity Troponin T Levels in Kidney Transplant Recipients

The Main Causes and Mechanisms of Increase in Cardiac Troponin Concentrations Other Than Acute Myocardial Infarction (Part 1): Physical Exertion, Inflammatory Heart Disease, Pulmonary Embolism, Renal Failure, Sepsis

The causes and mechanisms of increased cardiac troponin T and I (cTnT and cTnI) concentrations are numerous and are not limited to acute myocardial infarction (AMI) (ischemic necrosis of cardiac myocytes). Any type of reversible or irreversible cardiomyocyte injury can result in elevated serum cTnT and cTnI levels. Researchers and practitioners involved in the diagnosis and treatment of cardiovascular disease, including AMI, should know the key causes and mechanisms of elevated serum cTnT and cTnI levels. This will allow to reduce or completely avoid diagnostic errors and help to choose the most correct tactics for further patient management. The purpose of this article is to discuss the main causes and mechanisms of increase in cardiac troponins concentrations in frequently occurring physiological (physical exertion, psycho-emotional stress) and pathological conditions (inflammatory heart disease, pulmonary embolism, chronic renal failure and sepsis (systemic inflammatory response)) not related to myocardial infarction.

Elevation Mechanisms and Diagnostic Consideration of Cardiac Troponins under Conditions Not Associated with Myocardial Infarction. Part 1

Although cardiac troponins are considered the most specific biomarkers for the diagnosis of acute myocardial infarction (AMI), their diagnostic consideration goes far beyond the detection of this dangerous disease. The mechanisms of cardiac troponin elevation are extremely numerous and not limited to ischemic necrosis of cardiac myocytes. Practitioners should be well aware of the underlying pathological and physiological conditions that can lead to elevated serum levels of cardiac troponins to avoid differential diagnostic errors, which will be greatly increased if clinicians rely on laboratory data alone. This article presents a classification of the main causes of an elevation in cardiac troponins and discusses in detail the mechanisms of such elevation and the diagnostic consideration of cardiac troponins in some conditions not associated with AMI, such as physical exertion, inflammatory heart diseases (myocarditis and endocarditis), pulmonary embolism (PE), renal failure, and systemic inflammation (sepsis).

Pretransplant NT-proBNP, Dialysis Vintage, and Posttransplant Mortality in Kidney Transplant Recipients

BACKGROUND

End-stage kidney disease and dialysis vintage are characterized by accelerated atherosclerosis, volume overload, and progressive left ventricular hypertrophy, leading to elevated N-terminal probrain natriuretic peptide (NT-proBNP) levels. Pretransplant dialysis vintage is associated with excess mortality after transplantation. We want to study whether pretransplant NT-proBNP is associated with posttransplantation mortality and if it explains the association of dialysis vintage with posttransplantation mortality in kidney transplant recipients (KTR).

METHODS

We measured plasma NT-proBNP on arrival at the hospital before kidney transplantation in 658 KTR between January 1995 and December 2005 in our center. Multivariable Cox regression analyses, adjusted for potential confounders, were used to prospectively study the associations of dialysis vintage and NT-proBNP with all-cause mortality.

RESULTS

During median 12.7 (7.8-15.6) years of follow-up after transplantation, 248 (37.7%) KTR died. Dialysis vintage was associated with an increased risk of posttransplant mortality in the fully adjusted model (hazard ratio [HR], 1.22; 95% confidence interval [CI], 1.03-1.43; P = 0.02), independent of potential confounders. The association weakened materially and lost significance after further adjustment for NT-proBNP (HR, 1.14; 0.96-1.34; P = 0.14). NT-proBNP was independently associated with all-cause mortality in the fully adjusted model (HR, 1.34; 1.16-1.55; P < 0.001). The association remained independent of adjustment for dialysis vintage (HR, 1.31; 1.13-1.52; P < 0.001).

CONCLUSIONS

Our study shows that longer dialysis vintage is associated with a higher mortality risk in KTR, and this association might be explained for a considerable part by variation in pretransplant NT-proBNP at the time of transplantation.

B-Type Natriuretic Peptide and Cardiac Troponin I Are Associated With Adverse Outcomes in Stable Kidney Transplant Recipients

BACKGROUND

Approximately 200 000 kidney transplant recipients are living in the United States; they are at increased risk for cardiovascular and other adverse outcomes. Biomarkers predicting these outcomes are needed. Using specimens collected during the Folic Acid for Vascular Outcome Reduction in Transplantation trial, we determined whether plasma levels of B-type natriuretic peptide (BNP) and cardiac troponin I are associated with adverse outcomes in stable kidney transplant recipients.

METHODS

Five hundred ten subjects were selected randomly from the 4110 Folic Acid for Vascular Outcome Reduction in Transplantation participants. This cohort was then enriched for all additional subjects with adverse outcomes (death, dialysis-dependent kidney failure (DDKF), and cardiovascular outcomes) for a total of 1131 participants studied. Quartiles of BNP and high-sensitivity cardiac troponin I (hs-cTnI) were included in adjusted models. Combinations of normal and elevated hs-cTnI (>26.2 ng/L) and BNP (>100 pg/mL) were also studied.

RESULTS

Median concentrations (interquartile ranges) were 5.6 (3.3-10.5) ng/L for hs-cTnI and 39 (15, 94) pg/mL for BNP. Hazard ratios for each adverse outcome were higher with higher quartiles of BNP after adjustment and remained statistically significant after adding hs-cTnI to the model. The highest quartile hazard ratio for DDKF was 2.47 (95% confidence interval [95% CI], 1.21-5.05). Simultaneous elevations of BNP and hs-cTnI over clinical cutoffs were strongly associated with adverse outcomes with hazard ratios 8.8 (95% CI, 3.4-23.1) for DDKF and 6.3 (95% CI, 2.7-15.0) for cardiovascular outcomes.

CONCLUSIONS

Higher BNP is associated with mortality and cardiovascular and kidney outcomes in stable kidney transplant recipients. Elevated BNP and hs-cTnI identify candidates for targeted risk reduction.