3.4.1. Changes in the Levels of Tn I 
During the follow-up, elevation of Tn I was found in 20 patients (42%). Of these patients, five (24%) were in ivabradine and fifteen (56%) in the controls (Tn I elevation was observed four times more frequently in the controls than in the ivabradine group patients (OR [95% CI] = 4 [1.136, 14.085], The most significant increase in median Tn I was observed after four cycles of AC: 10 (6–21) in the ivabradine group (