Cardiac troponins and chronic kidney disease

The prevalence of coronary artery disease in patients with chronic kidney disease (CKD) is high, and acute myocardial infarction contributes significantly to the steep mortality rate in this population. Diagnosing an acute coronary syndrome in these patients is often difficult though essential. Traditional diagnostic tools such as symptoms and electrocardiographic manifestations are not entirely helpful in patients with CKD, and physicians are often left to rely on laboratory analysis of biomarkers such as cardiac troponin. However, troponin levels are increased in patients with renal failure in the absence of clinical myocardial ischemia, making their interpretation problematic. Several theories have been proposed for the mechanism of elevated troponin levels in CKD. Irrespective of our uncertainty regarding mechanism, studies have shown that there is a strong prognostic implication of elevated troponin levels; and that it is predictive of increased risk of mortality and cardiovascular events. Troponin levels rise over 6-8 h in the setting of acute myocardial injury; hence, it is imperative to obtain these levels sequentially in patients with CKD in whom a clinical cardiac event is suspected. A distinct rise and fall in the levels over baseline strongly support the diagnosis of acute myocardial necrosis. Despite uncertainties regarding increased troponins in patients with CKD, their value remains clear.