The prevalence of cardiac troponin autoantibodies is comparable in cardiac patients and healthy individuals and irrespective of age, sex and comorbidities

Background Commercial cardiac troponin (cTn) assays may be significantly affected by circulating cTn-binding autoantibodies (cTnAAb), which can lead to falsely low levels of cTn or elevations in the absence of myocardial injury. Despite the risk of analytical interference, data on the prevalence and clinical correlates of cTnAAbs remain limited. Purpose To determine the prevalence of cTnAAbs in patients with cardiac conditions and in a healthy population, and to investigate whether age, sex, and comorbidities are associated with the production of cTnAAbs. Methods Lithium-heparin plasma (Li-Hep) samples were obtained from 30 patients with non-ST-elevation myocardial infarction (NSTEMI), preoperatively from 19 patients with aortic stenosis scheduled for transcatheter aortic valve implantation (TAVI) and 151 patients scheduled for open-heart surgery, and from 314 healthy individuals. The presence of cTnAAbs was detected using a previously established in-house immunoassay. High-sensitivity cTnT (hs-cTnT) was measured with the Elecsys Troponin T hs kit (cobas e801, Roche Diagnostics). Associations between cTnAAbs and age, sex, hypertension, dyslipidemia, and diabetes were investigated. Statistical comparisons were performed using nonparametric tests. Results We detected cTnAAbs in 2 out of 30 (6.7%) NSTEMI patients, 2 out of 19 (10.5%) elective TAVI operation patients and in 16 out of 151 (10.6%) elective open-heart surgery patients. Overall prevalence of cTnAAbs was 20 out of 200 (10%) in all cardiac patients and 19 out of 314 (6.1%) in healthy individuals (p>0.05). Median [25th-75th percentile] age of NSTEMI patients, TAVI patients, open-heart surgery patients, and healthy individuals were 70 [64-79], 82 [77-84], 66 [58-71], and 50 [33-62] years, respectively. No significant differences in ages were found between cTnAAb-positive and cTnAAb-negative individuals within groups. Measured hs-cTnT levels were similar in individuals with and without cTnAAbs across all groups (Figure 1). The prevalence of cTnAAbs was consistent in both females and males irrespective of cardiac conditions (Table 1). Furthermore, no associations were found between the production of cTnAAbs and smoking, hypertension, dyslipidemia, or diabetes. Conclusions The prevalence of cTnAAbs is comparable in patients with significant cardiac conditions and healthy individuals. Moreover, cTnAAb production appears independent of age, sex, smoking and common comorbidities. Roche hs-cTnT assay seems unaffected by cTnAAbs. Due to the consistent ~10% cTnAAb prevalence in both cardiac patients and the general population, clinicians should be aware of possible cTnAAb-mediated interferences when interpreting cTn results.