Multi-polar stimulation of the left ventricle during cardio-resynchronisation therapy in patients with congestive heart failure: Randomised pilot study outcomes from parallel groups

Abstract

<p><strong>Background.</strong> Cardiac resynchronisation therapy (CRT) has been used for the treatment of patients with congestive heart failure (CHF) and wide QRS complexes for more than ten years. Nevertheless, the percentage of patients unresponsive to this therapy is 30%. There is recent evidence for increased responder proportions to treatments with multipolar pacing of the left ventricle (LV) in CRT. Accordingly, the aim of this study is to evaluate the effectiveness of multi-polar pacing of LV in patients with CHF and indications for CRT.</p><p><strong>Methods.</strong> Sixty-two patients [42 men, mean age 62.5 (58–68) years] with CHF and indications for CRT (for example patients with symptomatic heart failure and QRS duration ≥130 ms with left bundle branch block and left ventricular ejection fraction ≤ 35%) were included in this prospective, pilot, randomised study. Patients were implanted with cardiac resynchronisation devices with multi-polar electrodes. After implantation, patients were randomised into two groups according to the programming of the LV stimulation vector: true bipolar stimulation (group 1, stimulation vector LVring-LVtip, n = 31) and extended-bipolar LV stimulation (group 2, standard programming LV ring to RV, n = 31). The main objective of the study was to assess the effects of true bipolar stimulation on the increase of the number of CRT responders. Responders were defined as patients with a 15% decrease in the left ventricular end systolic volume compared with the initial characteristics as detected by echocardiography. Secondary points included changes in a) left ventricular ejection fraction (LVEF), b) 6-min walk test dynamics, and c) brain natriuretic peptide. The observation period was 12 months.</p><p><strong>Results.</strong> The LV electrode was implanted in the anterior (6%), antero-lateral (8%), lateral (18%), posterior (2%), or postero-lateral (66%) branches of the coronary sinus, and the average LV stimulation threshold was 1.7 ± 1.1 V. No intra-operative complications were detected. Four patients (6.5%) underwent LV electrode re-positioning on the second day after surgery owing to diaphragmatic nerve stimulation. At the end of the observation period, the average threshold used for LV stimulation of patients in the true bi-polar stimulation group with the LVring-LVtip vector was 1.9 ± 1.5 V compared with 1.6 ± 1.3 V in the case of the extended-bipolar LV stimulation group (p = 0.88). The number of responders in the true bipolar stimulation group was 25 (80.6%) compared with 21 (67.7%) patients in the extended-bipolar LV stimulation group (p = 0.38). LVEF significantly increased in both groups compared with pre-operative values without significant differences between the groups (29.4 vs. 36.5, p < 0.001 in the extended bipolar LV stimulation group; 28.0 vs. 34.9, p < 0.001 in the true bi-polar stimulation group, p = 0.86 between groups). The distance covered during the 6-min walk test significantly increased in both groups compared with pre-operative values in the absence of a significant difference between the groups (p = 0.92). The decreased levels of the cerebral natriuretic peptide were 60.3 ± 42.3 pg/ml and 56.6 ± 38.5 pg/ml in the extended and true bipolar stimulation groups, respectively (p = 0.95). </p><p><strong>Conclusion.</strong> Based on the results of this pilot study, the choice of a vector for true bipolar LV stimulation demonstrated its advantage and tendency to increase the number of responders in subjects with implanted CRT devices. Subsequent multi-centre randomised trials will help determine the role of true bipolar LV stimulation and extended-bipolar stimulation from different regions of the LV to increase the response to CRT.</p><p><br />Received 24 December 2019. Revised 18 January 2020. Accepted 20 January 2020.</p><p><strong>Funding:</strong> The work is supported by a grant of the President of the Russian Federation No. МД-2893.2018.7.</p><p><strong>Conflict of interest:</strong> Authors declare no conflict of interest.</p><p><strong>Author contributions</strong><br />Conception and study design: A.B. Romanov<br />Data collection and analysis: A.V. Ponomarenko, I.L. Mikheenko, E.A. Morzhanayev, A.G. Filippenko, R.E. Zhizhov, I.S. Peregudov<br />Statistical analysis: A.B. Romanov, I.L. Mikheenko<br />Drafting the article: A.V. Ponomarenko, I.L. Mikheenko, E.A. Morzhanayev<br />Critical revision of the article: A.B. Romanov, D.V. Losik, I.L. Mikheenko, A.V. Ponomarenko, V.V. Shabanov, S.N. Artemenko <br />Final approval of the version to be published: A.V. Ponomarenko, I.L. Mikheenko, E.A. Morzhanayev, A.G. Filippenko, D.V. Losik, V.V. Shabanov, I.S. Peregudov, R.E. Zhizhov, A.B. Romanov, S.N. Artemenko</p>