176-70: Cardiac resynchronization therapy: long-term results of atrioventricular and interventricular delay optimization by ECG

Abstract

Purpose: To assess the role of atrioventricular (AVD) and interventricular delay (VVD) optimization in CRT devices based on changes in PR interval and the width of QRS complex using standard ECG on hemodynamic parameters in the five year period. Materials and methods: The randomized study involving 128 patients in sinus rhythm after CRT implantation according to the guidelines. 2 patient groups were taken: 1) AVD and VVD optimization, n = 63, 2) only AVD optimization (conventional treatment), n = 65. Standard follow-up protocol, echocardiography as well as optimization of AVD and VVD were carried out every 6 months during 5 years. The target sensed/paced AV interval was assumed to the finished symmetrical intrinsic/stimulated P wave respectively. VVD optimization was implemented by gradual change of stimulation delay time of the right/left ventricle preactivation (from zero to 40 ms) and simultaneous measurement of the biventricular QRS width on ECG. The final VVD was assumed to the narrowest biventricular QRS complex (bivQRS). The heart failure (HF) functional class assessing was implemented by clinical evaluation and a six-minute walk test. Results: There were no differences in HF etiology, ECG and echocardiography parameters between the groups. For 5 year follow-up there was significant reduction in the bivQRS width in Group I, p = 0.042. Final values of the bivQRS and intrinsic QRS width were lower in Group I, p = 0.016 and p = 0.044 respectively. End-systolic and end-diastolic LV volumes decreased in both groups; reduction in the end-systolic LV volume was greater in Group I, p = 0.039. Ejection fraction (EF) increased in both groups, the degree of EF increase was higher in Group I, p = 0.048. Normalization of LV systolic function (EF ≥ 50%) occurred in 16 patients in Group I and 4 patients in Group II, p = 0.033. HF functional class decreased in both groups; the final value was lower in Group I, 2.12 versus 2.64 in Group II, p = 0.022. The survival analysis (Kaplan-Meier) showed no significant differences: p = 0.787 (Log-Rank test).