Assessment of Factors Determining Efficacy of Cardiac Resynchronisation Therapy for Patients with Heart Failure in the Population of Latvia. Summary of the Doctoral Thesis

Abstract

Introduction. Heart failure (HF) is one of the main causes of hospitalisation, disabilities and death worldwide and in Latvia as well. Pharmacological therapy often has proven to be ineffective since it fails to prevent uncoordinated ventricular contraction. Application of cardiac resynchronisation therapy (CRT) helps restore proper coordination between both ventricles, thus improving the HF prognosis. Nevertheless, it remains unclear what initial factors may affect the CRT efficiency. Aim. The aim of the study is to analyse progression of treatment and the factors affecting the efficiency in HF patients with moderate and severe clinical course with implanted cardiac resynchronisation devices. Methods. The prospective single-centre study analysed patients with HF who had undergone scheduled implantation of CRT. Efficiency of CRT was detected by echocardiography, studying the improvement in ejection fraction (EF) of the left ventricular after 12 and 24 months, respectively. ΔEF improvement ≥ 10% – CRT responders and ΔEF improvement <10% – CRT non-responders. The study focused on the analysis of the initial clinical, laboratory factors, electrocardiographic, echocardiographic, programmed parameters of CRT devices and their changes within 12 and 24 months. Results. ΔEF improvement ≥ 10% within 24 months was observed in 27 (60.0%) patients. After CRT implantation, patient hospitalisation due to HF decompensation decreased statistically significant, functional class (FC) of HF and 6-minute walking test improved, value of natriuretic factors decreased and EchoCG parameters improved. Patients (n = 27) with ΔEF ≥ 10% showed statistically significant higher average systolic blood pressure (SBP), wider QRS and more prominent interventricular mechanical dyssynchrony (IVMD) compared to patients (n = 18) with ΔEF < 10%: 131.89 ± 14.73 versus (vs.) 117.78 ± 14.37 mm Hg; p = 0.003, 175.15 ± 20.29 vs. 161.22 ± 25.40 ms; p = 0.048, 51.37 ± 9.45 vs. 27.65 ± 13.5 ms; p < 0.001, respectively. Patients with left His bundle branch block (LBBB) (n = 35) statistically significant more often were in the CRT efficiency group in comparison to patients without LBBB (n = 10) – 26 (96.3%) vs. 1 (3.7%; p < 0.001), respectively. Patients (n = 21) with a scar in the left ventricle wall statistically significant less frequent were in the CRT efficiency group compared to the patients without a scar (n = 24) – 7 (25.9%) vs. 20 (74.1%; p = 0.001), respectively. Patients with left ventricle before right ventricle (n = 22) statistically significantly / significant more frequent were in the CRT efficiency group compared to the patients with a different stimulation sequence (n = 23) – 17 (63.0%) vs. 10 (37.0%; p = 0.021), respectively. Multivariate analysis indicates that the most significant CRT efficiency affecting factors initially were LBBB, significant – IVMD, higher SBP. Conclusions. More than a half of the study population reached CRT efficiency. CRT implantation is a safe and effective HF treatment method. Predominant prognostic CRT efficacy factors are baseline LBBB, IVMD > 50 ms, SBP above 130 mm Hg.