Immulite 2000 troponin 1 test

Venous blood samples were collected both in tubes containing ethylendiaminetetraacetic acid (EDTA) and in serum tubes. Samples in EDTA tubes were centrifuged immediately after collection (4°C; 3500g). Serum samples were centrifuged 15‐20 minutes after collection (25°C; 4000g). One serum aliquot was shipped on the day of the blood collection to an external laboratory (IDEXX Laboratories, Ludwigsburg, Germany) for the measurement of the cTnI concentration, using a conventional cTnI assay (Immulite 2000 troponin I test; Siemens Healthcare Diagnostics) with a detection limit of 0.2 ng/mL (measuring range 0.2‐180 ng/mL). Remaining serum and EDTA‐plasma samples were stored in batches at −80°C until being shipped on dry ice to the same external laboratory (IDEXX Laboratories) for the determination of the cTnI concentrations from serum and EDTA‐plasma by the hs‐cTnI assay (Advia Centaur TnI‐Ultra assay; Siemens Healthcare Diagnostics). The hs‐cTnI assay is a second‐generation sandwich immunoassay using 3 different antibodies and direct chemiluminometry. The detection limit of this assay is 0.006 ng/mL (measuring range 0.006‐50 ng/mL). Urea and creatinine concentrations were measured in‐house (Cobas Integra 400 plus; Roche Diagnostics, Rotkreuz, Switzerland).

Medical history was gathered and a complete examination was performed both at first presentation and at every control examination. Healthy DP were examined at least once a year. Doberman Pinschers with an increased cTnI concentration (using a conventional cTnI assay; Immulite 2000 troponin I test; Siemens Healthcare Diagnostics) or short coupling interval of VPC (despite having less than 50 VPC/24 hours) were rechecked every 6 months. Doberman Pinschers with DCM were rechecked more frequently.
Each examination included a general clinical examination, echocardiography, 5‐minute ECG, 24‐hour ECG, and measurement of cTnI‐, urea‐, and creatinine concentrations. Complete blood count analyses and biochemistry screens were conducted when the result of the general clinical examination was abnormal.