Elevated concentrations of cardiac troponins are associated with severe coronary artery calcification in asymptomatic haemodialysis patients

Sir, We read with interest the article by Jung et al. [1] entitled ‘Elevated concentrations of cardiac troponins are associated with severe coronary artery calcification in asymptomatic haemodialysis patients’. They found, in haemodialysis patients, a significant correlation between elevated levels of cardiac troponin T (cTnT) and levels above the detection limit of cardiac troponin I (cTnI), with the severity of coronary arterial calcification (CAC), as discovered by multirow spiral computed tomography. However, the statement that ‘cardiac troponins are commonly elevated in patients with ESRD’ may be true for cTnT, but is not to the same degree applicable to cTnI. In fact, the study of Apple et al. [2] cited by the authors found a much lower frequency of elevated levels of cTnI as compared with cTnT in 733 dialysis patients. Jung et al. [1] reported elevated cTnT levels (>0.1 ng/ml: the cut-off level for myocardial infarction) in 29% of the 38 patients, whereas elevated cTnI-levels (defined as >0.5 ng/ml) were observed in only 8% of the patients (n1⁄4 3). Only one patient had a cTnI concentration above the cut-off level for a myocardial infarction ( 2.0 ng/ml). Using the same method of measuring cTnI, we found, in a group of 93 dialysis patients, 9 cases (9.7%) with detectable levels of cTnI ( 0.1 ng/ml), but below 2.0 ng/ml. None of the patients had a cTnI concentration above this level [3]. The formulation of the conclusion by Jung et al. [1] as stated in the Abstract and at the end of the article, that ‘elevated concentrations of cTnT and cTnI were independently associated with . . .’, is therefore debatable. The positive correlation of cTnI with CAC was observed not only in the three cases of ‘elevated cTnI’ (>0.5 ng/ml), but also with the whole group of 14 patients with detectable cTnI-levels ( 0.1 ng/ml), thus including the cases of cTnI below 0.5 ng/ml (n1⁄4 11). The study confirms that in dialysis patients elevated levels of cTnT and levels above the detection limit of cTnI should, in view of their prognostic significance [2,3], be taken seriously by their treating physicians.