Journal of Interventional Cardiac Electrophysiology 10, 37–45, 2004 C  2004 Kluwer Academic Publishers. Manufactured in The Netherlands. Triple-Site Pacing in Patients with Biventricular Device—Incidence of the Phenomenon and Cardiac Resynchronization Benefit Alan Bulava, 1 Gerardo Ansalone, 2 Renato Ricci, 2 Paride Giannantoni, 2 Carlo Pignalberi, 2 Petr Heinc, 1 Jan Lukl, 1 and Massimo Santini 2 1 I. Department of Medicine, University Hospital Olomouc, I.P. Pavlova 6, 775 20 Olomouc, Czech Republic; 2 Department of Cardiac Diseases, San Filippo Neri Hospital, Via G.B. Martinotti 20, 00135 Rome, Italy Abstract. Background: In patients with biventricular pacing (BIV), triple-site pacing (TSP), i.e. standard biventricular cathodal pacing of the right and the left ventricle plus additional anodal capture of the right ventricle, is sometimes present. Aims: To evaluate the incidence of TSP phenomenon, to examine TSP-related QRS changes, and to as- sess the effect of TSP on intraventricular resyn- chronization by means of tissue Doppler imaging (TDI). Methods and results: 23 patients with a first gener- ation biventricular device (Medtronic 8040) and 16 pa- tients with a new generation device (Medtronic 8042) were evaluated to look for the presence of TSP. TSP was found in 6 patients (26%) with the Medtronic 8040 (group I) and in 13 patients (81%) with the Medtronic 8042 device (group II). QRS duration decreased by 10 to 20 ms and QRS amplitude of leads I and aVL increased in almost all patients in group I during TSP modality. In group II, QRS morphology, duration and amplitude did not change as obviously. TDI analysis of the left ven- tricular (LV) basal segments showed significant short- ening of the systole, together with a corresponding pro- longation of the diastole, at the inferior wall of the LV, during TSP compared to standard BIV in all patients ( p < 0.01). Other LV segments did not show any change. Qualitative TDI electro-mechanical activation pattern of all LV segments improved in 22%, while it remained unchanged in 72%. Conclusions: TSP phenomenon can be identified in approximately a quarter of patients with the first- generation biventricular devices on the basis of the QRS morphology changes. In the second-generation biven- tricular pacemakers it can be demonstrated in the vast majority of patients. TSP may increase the effectiveness of cardiac resynchronization therapy by counteracting the regional activation delay located at the inferior wall of the LV. Key Words. biventricular pacing, cardiac resyn- chronization, anodal stimulation, tissue Doppler imaging Introduction Biventricular pacing is a new non pharmacologi- cal approach for treatment of patients with mod- erate to severe congestive heart failure and inter- or intraventricular conduction delay and has been associated with improved New York Heart Asso- ciation (NYHA) functional class, increased exer- cise tolerance and better quality of life [1–5]. New echocardiographic techniques, and in particular Tissue Doppler Imaging (TDI) analysis, have been proved to be a helpful tool in evaluating cardiac dyssynchrony, as well as in assessing the degree of cardiac resynchronization after biventricular de- vice implantation [6,7]. Recently, a phenomenon of anodal capture of the right ventricle in patients wearing a biventricu- lar pacemaker has been described [8,9]. The phe- nomenon may be defined as “triple-site pacing”, when considering that it is the result of cathodal pacing in both ventricles with the additional an- odal capture of the right ventricle. To our knowl- edge, triple-site pacing incidence and its impact on cardiac resynchronization have not been yet con- sistently evaluated. The aims of our study were: (1) to evaluate the incidence of triple-site pacing, (2) to compare the effects of triple-site pacing on ventricular depo- larization pattern and frontal QRS axis with the conventional right and left ventricular cathodal Address for correspondence: Alan Bulava, MD, I. Depart- ment of Medicine, University Hospital, I. P. Pavlova 6, 775 20 Olomouc, Czech Republic. E-mail: alanbulava@hotmail.com Received 20 January 2003; accepted 21 July 2003 37