Plasma levels of mitochondrial and nuclear DNA in patients with massive pulmonary embolism in the emergency department: a prospective cohort study

Abstract

Introduction: Cell-free plasma mitochondrial DNA (mt-DNA) and nuclear DNA (n-DNA) are biomarkers with prognostic utility in conditions associated with a high rate of cell death. This exploratory study aimed to determine the plasma levels of both nucleic acids in patients with massive and submassive pulmonary embolism (PE) and to compare them with other biomarkers, such as heart-type fatty acid-binding protein (H-FABP) and troponin I (Tn-I) METHODS: This was a prospective observational study of 37 consecutive patients with massive PE, 37 patients with submassive PE, and 37 healthy subjects. Quantifications of plasma mt-DNA and n-DNA with real-time quantitative polymerase chain reaction (PCR), and plasma H-FABP and Tn-I by commercial assays, were done on blood samples drawn within 4 hours after presentation at the emergency department.

Results: Plasma mt-DNA and n-DNA concentrations were much higher in patients with massive PE (median, 2,970 GE/ml; interquartile range (IQR), 1,050 to 5,485; and 3,325 GE/ml, IQR: 1,080 to 5,790, respectively) than in patients with submassive PE (870 GE/ml and 1,245 GE/ml, respectively; P < 0.01) or controls (185 GE/ml and 520 GE/ml, respectively). Eighteen patients with massive PE died of a PE-related cause by day 15 of observation. Plasma mt-DNA and n-DNA values were 2.3-fold and 1.9-fold higher in the subgroup of nonsurviving patients than in survivors. H-FABP and Tn-I values were also higher in patients with massive PE who died (7.3 ng/ml and 0.023 ng/ml, respectively) than in those who survived (6.4 ng/ml, and 0.016 ng/ml, respectively). By receiver operating curve (ROC) analysis, the best cutoff values for predicting 15-day mortality were 3,380 GE/ml for mt-DNA, 6.8 ng/ml for H-FABP, 3,625 GE/ml for n-DNA, and 0.020 ng/ml for Tn-I, based on the calculated areas under the curve (AUCs) of 0.89 (95% confidence interval (CI), 0.78 to 0.99), 0.76 (95% CI, 0.69 to 093), 0.73 (95% CI, 0.58 to 0.91), and 0.59 (95% CI, 0.41 to 0.79), respectively. By stepwise logistic regression, a plasma mt-DNA concentration greater than 3,380 GE/ml (adjusted odds ratio (OR), 8.22; 95% CI, 1.72 to 39.18; P < 0.001) and a plasma value of H-FBAP >6.8 ng/ml (OR, 5.36; 95% CI, 1.06 to 27.08; P < 0.01) were the only independent predictors of mortality.

Conclusions: mt-DNA and H-FBAP might be promising markers for predicting 15-day mortality in massive PE, with mt-DNA having better prognostic accuracy.

Figure 1

ROC curves for the use of plasma mt-DNA, and H-FBAP concentrations to predict 15-day mortality. Plasma mt-DNA had better predictive value (AUC, 0.89; 95% CI, 0.78 to 0.99) than did plasma H-FBAP (AUC, 0.76; 95% CI, 0.69 to 0.93). The best cut-off value of plasma mt-DNA at admission was 3,380 GE/ml (sensitivity, 94.4%; specificity, 68.4%). The best cut-off value of plasma H-FBAP was 6.8 ng/ml (sensitivity, 88.9%; specificity, 85.7%).

Figure 2

ROC curves for the use of plasma n-DNA and Tn-I, to predict 15-day mortality. The best cut-offs were 3,625 GE/ml for n-DNA, and 0.020 ng/ml for Tn-I, based on the calculated AUCs of 0.73 (95% CI, 0.60 to 0.91) and 0.599 (95% CI, 0.41 to 0.79), respectively.

Figure 3

Kaplan-Meier survival curve analysis according to the plasma concentration of (A) mt-DNA level higher or lower than 3,380 GE/ml; log rank: χ², 13.71; P < 0.001. (B) H-FBAP level higher or lower than 6.8 ng/ml; log rank: χ², 12.65; P < 0.001. (C) n-DNA level higher or lower than 3,625 GE/ml; log rank: χ², 6.84; P < 0.009.