Troponin T for the detection of dialysis-induced myocardial stunning in hemodialysis patients

Abstract

Background and objectives: Circulating troponin T levels are frequently elevated in patients undergoing long-term dialysis. The pathophysiology underlying these elevations is controversial.

Design, setting, participants, & measurements: In 70 prevalent hemodialysis (HD) patients, HD-induced myocardial stunning was assessed echocardiographically at baseline and after 12 months. Nineteen patients were not available for the follow-up analysis. The extent to which predialysis troponin T was associated with the occurrence of HD-induced myocardial stunning was assessed as the primary endpoint.

Results: The median troponin T level in this hemodialysis cohort was 0.06 ng/ml (interquartile range, 0.02-0.10). At baseline, 64% of patients experienced myocardial stunning. These patients showed significantly higher troponin T levels than patients without stunning (0.08 ng/ml [0.05-0.12] versus 0.02 ng/ml [0.01-0.05]). Troponin T levels were significantly correlated to measures of myocardial stunning severity (number of affected segments: r=0.42; change in ejection fraction from beginning of dialysis to end of dialysis: r=-0.45). In receiver-operating characteristic analyses, predialytic troponin T achieved an area under the curve of 0.82 for the detection of myocardial stunning. In multivariable analysis, only ultrafiltration volume (odds ratio, 4.38 for every additional liter) and troponin T (odds ratio, 9.33 for every additional 0.1 ng/ml) were independently associated with myocardial stunning. After 12 months, nine patients had newly developed myocardial stunning and showed a significant increase in troponin T over baseline (0.03 ng/ml at baseline versus 0.05 ng/ml at year 1).

Conclusions: Troponin T levels in HD patients are associated with the presence and severity of HD-induced myocardial stunning.

Figure 1.

Histogram showing the frequency distribution of troponin T levels in 70 prevalent hemodialysis patients. The dashed line separates values above and below 0.03 ng/ml (commonly used to detect acute myocardial infarction in the setting of acute chest pain), and the solid line separates values above and below 0.06 ng/ml (median value of this hemodialysis population).

Figure 2.

Receiver-operating characteristic curve displaying the potential predialytic troponin T values to detect hemodialysis-induced myocardial stunning. AUC, area under the receiver-operating characteristic curve. Sens, sensitivity; Spec, specificity.

Figure 3.

Boxplots displaying troponin T levels at baseline (dark) and at year 1 (light). All 33 patients with stunning at baseline and being followed up after 1 year also had stunning at year 1. Five patients without stunning at baseline were not followed up for 1 year and are counted as “never stunning.” P values are derived from Wilcoxon test for paired samples and include only patients sampled at both time points. The top of the box represents the 75th percentile, the bottom of the box represents the 25th percentile, and the line in the middle represents the 50th percentile (median). The whiskers represent the highest and lowest values (excluding outliers).