Biochemical markers
Venous blood samples were obtained from all patients from an antecubital vein after at least 15 min of semisupine rest. Blood samples were collected into tubes containing ethylenediaminetetraacetic acid (EDTA) to prevent coagulation. Troponin-I levels were measured by chemiluminescent immunoassay using an Immulite 2500 device (Siemens Medical Solutions, Erlangen, Germany).