THE POTENTIAL OF USING THE DYNAMICS OF ELECTROCARDIOGRAPHIC PARAMETERS IN DETECTING CARDIOTOXICITY 12 MONTHS AFTER THE END OF CHEMOTHERAPY FOR BREAST CANCER WITH DOXORUBICIN

Background. Changes in electrocardiographic parameters of the heart, reflecting the processes of depolarization and repolarization of the myocardium, can be signs of early cardiotoxicity (CT). Aim. To study changes in electrocardiographic parameters of the myocardium in patients with verified breast cancer 12 months after the end of chemotherapy with doxorubicin. Material and methods. The study included 100 patients with a confirmed diagnosis of breast cancer who were treated at the health care institution “Grodno University Clinic” (Grodno, Belarus). A number of electrocardiographic parameters of the myocardium were measured in patients before and 12 months after the end of chemotherapy using electrocardiography and 24-hour Holter monitoring. Results. A statistically significant increase in electrocardiographic parameters of depolarization and repolarization was revealed (P, P-Q, Tpeak-Tend, Q-Tc / QRS, Q-Tc - p<0.007; p<0.001; p=0.042; p=0.009; p<0.001, respectively) before and 12 months after the end of chemotherapy. A change in the time and total number of episodes of sinus tachycardia and supraventricular extrasystoles was also noted (p=0.029, p=0.026 and p=0.002). The Tpeak-Tend indicator changed statistically significantly in the CT+ subgroup (p=0.032) after 12 months. The dynamics of the Q-Tc indicator before and 12 months after the end of chemotherapy was observed in almost all patients. However, in the CT+ subgroup, an increase in Q-Tc was recorded statistically significantly more often compared to the CT- subgroup (p <0.005). Conclusion. During chemotherapy with doxorubicin, an increase in Tpeak-Tend and Q-Tc was observed. An especially significant increase in these indicators was noted in the CT+ subgroup. The number and duration of sinus tachycardia episodes as well as the number of supraventricular extrasystoles also increased. This may correlate with the relationship between chemotherapy with doxorubicin and the dynamics of electrocardiographic parameters.