Effect of cardiac resynchronization therapy on ventricular tachycardias in patients with dilated cardiomyopathy and severe heart failure

The aim of the study was to elucidate the effects of cardiac resynchronization therapy (CRT) on ventricular tachycardias in patients with dilated cardiomyopathy and to analyze the prospects of radionuclide diagnostic methods for prediction of life-threatening arrhythmias in the presence of therapy. The study included 70 patients (mean age 55 ± 12 years) aged 32 to 75 years with dilated cardiomyopathy, NYHA FC III heart failure, left ventricular (LV) ejection fraction (EF) of 30.1 ± 3.8%, and end-diastolic volume (EDV) of 220.7 ± 50.9 mL. Group 1 comprised 35 patients (50%) diagnosed with paroxysms of ventricular tachycardia, while Group 2 consisted of 35 patients (50%) without episodes of ventricular tachycardia. After one year of CRT, positive clinical changes were documented in all patients: LV EF increased to 42.8 ± 4.8% (p ≤ 0.001); functional class of heart failure decreased to II; LV EDV decreased to 197.9 ± 47.8 mL (p ≤ 0.005). The patients whose EF increased by 14% and EDV decreased by 35 mL during one-year CRT had no episodes of ventricular tachycardia. The patients, whose paroxysms of ventricular tachycardia persisted during the entire period of the study, showed EF increase by 9% and EDV decrease by 13 mL. The second stage of the study consisted in evaluating the effects of myocardial metabolism defects (MMD). No ventricular tachycardia episodes were registered in patients whose MMD became less than 15% during CRT; if the size of DMM exceeded 15%, paroxysms of ventricular tachycardia were observed. Thus, efficacious CRT in patients with dilated cardiomyopathy results in a statistically significant reduction of the number of ventricular tachycardia episodes. The improvement of fatty acid metabolism contributes to a decrease in the number of ventricular tachycardia episodes in the course of CRT.