Comparison of Various Heart Pacing Methods Effectiveness on Patients with Heart Failure and Permanent Atrial Fibrillation. Summary of the Doctoral Thesis

Abstract

Thesis “Comparison of Various Heart Pacing Methods Effectiveness on Patients with Heart Failure and Permanent Atrial Fibrillation” focuses on one of the key issues in contemporary cardiology – the control of ventricular frequency in patients with permanent, highly symptomatic atrial fibrillation, which is unresponsive to pharmacotherapy. There have been significant changes in the choice of treatment tactics for severe heart failure since 2000. It especially concerns patients with permanent atrial fibrillation. Both in the 1990s and the beginning of 2000s radio frequency catheter ablation in the atrioventricular node followed by the implantation of a pacemaker (the method known in the international literature as Ellenbogen and Kay “Ablate and Pace” method) has been and remains one of the optional methods of heart rate control in patients with permanent AF and chronic heart failure (HF), although there is also enough contradictory data on the long-term effectiveness. Stable results achieved by the bundle of His RFCA and subsequent VVIR pacemaker implantation in the 90s have, as the examinations conducted after a sustained period of time have shown, presented difficulties in connection with heart failure development. The application of apical pacing was already in the late 90s subject to criticism as non-physiological and conducive to heart failure. In 1994 specific cardiac electrical stimulation method that re-coordinates the heart chambers by simultaneous stimulation of the right and left ventricles (CRT) was introduced to clinical practice. The method developed and CARE – HF study, published in 2005, convincingly endorsed its effectiveness for patients with severe heart failure. This method combined with AV node RFCA was subject to multicenter studies MILOS in 2007 and Neymayer in 2008. The results confirmed the efficiency of the method for severe heart failure patients, but at the same time, studies REVERSE, Madit - CRT and RAFT (all published between 2009 and 2011) also proved CRT methodology effective in moderate heart failure patients. However, despite this, several questions remain unclear and unanswered: Except for small-scale studies (Northern Italy Group, HOBIPACE), there is no long term observational data on non-pharmacological treatment options for heart failure in chronic AF patients who had undergone the AV node catheter ablation method. Classic, evidence-based and in the international guidelines recommended indications of the heart resynchronization therapy provide CRT system implantation in patients with left ventricular ejection fraction (LVEF) of ≤35%, complete left bundle branch block, cardiac dyssynchrony of >40 milliseconds (echocardiography [ECHO] with “Tissue Doppler Method”) and with maintained sinus rhythm. The data of AF patients is under observation in small separate centers. Optimal localization of the right ventricular stimulation electrode is still in discussion both in international press, as well as congresses and conferences. The aim of the study was to examine whether biventricular heart stimulation is superior to right ventricular tip and atrial septal electrostimulation in patients with permanent atrial fibrillation and moderate heart failure after the AV node RFCA. The study analysed data on treatment efficacy of 120 patients. Patients were divided into 3 groups, 40 patients for right ventricular tip stimulation, 40 patients for ventricular septal stimulation and 40 patients for biventricular stimulation (CRT). All patients prior to the pacemaker / CRT implantation had undergone AV node RFCA. All laboratory and clinical tests were conducted in accredited and certified laboratories. Statistical analysis was carried out using SPSS 12.0 software and Microsoft Office EXCEL. The duration of the observational study was 24 months. The study proved that the results were more effective in patients who have undergone CRT implantation than in those with the traditional tip and ventricular septal cardiac electrostimulation. The comparison of ECHO parameters showed, that in the CRT group, in contrast to right ventricular tip electrostimulation, left ventricular ejection fraction (LVEF) improved by 9.2%, left ventricular end-diastolic diameter (EDD) decreased by 6.8%, QRS interval length decreased by 28% and left ventricular dyssynchrony by 58%. Stabilisation of biochemical markers in heart failure was significantly more noticeable in CRT patients (B-type natriuretic peptide levels decreased by 13.5% more in the CRT group than in patients with ventricular septal electrostimulation). In the course of work a new methodology was developed, the procedure begins with the pacemaker / CRT implantation and then, after 30-40 days, AV node RFCA is carried out. A new methodology prevents the patient from life-threatening complications (no life-threatening complications, including ventricular arrhythmias, were observed during the procedures). Based on the above, it can be argued that to control the frequency in patients with highly symptomatic permanent atrial fibrillation using the “Ablate and Pace” treatment tactics, was more efficient than the left ventricle tip and ventricular septal cardiac electrostimulation. Our results showed beneficial effects of heart resynchronisation in patients without CRT indications, but according to the recommendations of leading experts CRT indications in patients with permanent, highly symptomatic atrial fibrillation can be expanded after the AV node RFCA. The study results and methodology are to be applied in the National Guidelines and practical treatment recommendations, they can also be used as a basis for other new studies on intra- and inter-ventricular input optimization in the treatment of heart failure by evaluating the difference between total mortality and mortality from heart failure in patients with highly symptomatic atrial fibrillation after the AV node RFCA and CRT / pacemaker implantation.