The implantation of pacemaker is the treatment of choice for patients with symptomatic bradycardia. Since the first implantation in 1958, millions of patients have undergone a pacemaker implantation. The number of implants isgetting higher every year. Optimal fixation of the pacemaker lead is achieved by active or passive fixation. The type of fixation is chosen by the operator regardless of the patient's clinical condition and operator's experience. Implantation of pacemaker causes microdamage to the heart muscle as measured by hsTnT values. Our trial is a prospective, randomized, multicentre trial that included 326 patients. Patients with indication for implantation of a permanent heart pacemakerwere centrally randomized to receive ventricular leads with active or passive fixation mechanism. Blood samples were taken on the morning of the implantation procedure and the next day. HsTnT was analysed using the Roche Elecsys Troponin T high Sensitive Test at each of the participating centres. The primary goal was to quantify the myocardial micro-damage attributable to the implantation procedure. The secondary goal was to determine the proportion of patients with hsTnT values that exceeded the upper reference, limit for the diagnosis of acute myocardial infarction. This research showed that there are no significant differences in the amount of damage to the heart muscle between active and passive electrode and that both types of fixation are equally traumatic to the heart muscle. 80% of patients after implantation have hsTnT values that exceed the limit for acute myocardial infarction diagnosis. Increased hsTnT values are associated with short-term and long-term patient prognosis. Therefore, new techniques and materials need to be evaluated in future. Techniques and materials that could reduce myocardial damage during pacemaker implatation should be consider.