The impact of left ventricular lead position on left ventricular reverse remodelling and improvement in mechanical dyssynchrony in cardiac resynchronization therapy.

AIMS: To investigate the influence of left ventricular (LV) lead position on LV dyssynchrony in cardiac resynchronization therapy (CRT). METHODS AND RESULTS: The LV lead was prospectively targeted to the latest activated LV segment (concordant) evaluated by two-dimensional speckle tracking radial strain (ST-RS) echocardiography in 103 CRT recipients (67 ± 12 years). Mechanical dyssynchrony was assessed by anteroseptal-to-posterior (AS-P) delay and interventricular mechanical delay (IVMD). Concordant LV leads were obtained in 72 (70%) patients. Superior LV reverse remodelling (LV-RR; ≥ 15% LV end-systolic volume reduction at 6-month follow-up) was observed in the concordant LV leads compared with the discordant LV leads [51 (76%) vs. 13 (45%); P = 0.003]. Mechanical resynchronization responders (≥ 50% AS-P delay reduction at 6-month follow-up) obtained in the concordant LV leads [44 (66%)] was greater than in the discordant LV leads [10 (34%); P = 0.005]. The discordant LV leads located adjacent to the concordant LV leads (+1 segment; n = 22) and 2 segments apart (+2 segments; n = 9) were evaluated in a subgroup analysis. Mechanical resynchronization responders 6 months after CRT were as follows: in +1 segment [n = 10 (48%)] and in +2 segments (n = 0; P = 0.001). The concordant LV lead was the only independent predictor of LV-RR at 6-month follow-up (odds ratio, 4.177; P = 0.004). Independent predictors of mechanical resynchronization responders were AS-P delay (odds ratio, 1.007; P = 0.032), IVMD (odds ratio, 1.024; P = 0.038), and concordant LV lead (odds ratio, 4.691; P = 0.004). CONCLUSION: Concordant LV leads in CRT provided more responders according to both LV reverse remodelling and mechanical resynchronization.

Right ventricular pacing and sensing function in high posterior septal and apical lead placement in cardiac resynchronization therapy.

BACKGROUND: The conventional right ventricular (RV) lead position in cardiac resynchronization therapy pacemakers (CRT-P) is the RV apex (RV-A). Little is known about electrophysiological stability and associated complications of pacing leads in RV high posterior septal (RV-HS) position in CRT-P. METHODS: Two hundred and thirty-five consecutive CRT-P patients were included from 1999-2010. Pacing thresholds at 0.5ms and 2.5V, sensing electrograms and lead impedances were measured at implant and repeated 1,3,6,12,18 and 24 months after CRT-P. Electrophysiological measurements of leads located in RV-A and RV-HS were analyzed retrospectively. Bipolar RV leads were used, including high impedance leads, passive fixation and active fixation. RESULTS: RV pacing leads were implanted in RV-A (n=79) and RV-HS (n=156). Average RV pacing thresholds from CRT implant procedure to 24-month follow-up at 0.5ms were 0.77±0.69V in RV-A and 0.71±0.35V in RV-HS (P=0.31), and at 2.5V were 0.06±0.08ms in RV-A and 0.07±0.05ms in RV-HS (P=0.12). Average RV electrogram amplitudes from baseline to 24 months after CRT were 15.3±6.9mV in RV-A and 12.1±6.0mV in RV-HS (P=0.55). Average RV impedances during follow-up were 850±286Ω in RV-A and 618±147Ω in RV-HS (P=0.57). Similar RV lead revisions between RV-A and RV-HS were observed after 2-year follow-up (P=0.55). CONCLUSION: The RV-HS lead position demonstrated stable and acceptable long-term pacing and sensing function, with rates of complications comparable to conventional RV-A lead position in CRT. The RV-HS lead position is feasible in CRT-P.

A randomized study of haemodynamic effects and left ventricular dyssynchrony in right ventricular apical vs. high posterior septal pacing in cardiac resynchronization therapy.

AIMS: The effect on left ventricular (LV) systolic function and LV dyssynchrony by alternative right ventricular (RV) lead position in cardiac resynchronization therapy (CRT) is unclear. In the present study, RV apical (RV-A) was compared with RV high posterior septal (RV-HS) lead position in CRT. METHODS AND RESULTS: In 85 consecutive CRT patients (mean age 66 ±11 years) the RV lead placement was randomized to RV-A (n = 43) or RV-HS (n = 42). The LV lead was targeted to the latest activated LV segment (concordant LV lead), identified by two-dimensional speckle tracking radial strain (ST-RS) echocardiography. Concordant LV leads were obtained in 72%, similar in RV-A and RV-HS (79% vs. 64%; P = 0.13). Six months after CRT, no difference was found in LV reverse remodelling (reduction of LV end-systolic volume ≥15%) according to RV-A and RV-HS leads [26 (65%) vs. 25 (64%); P = 0.93]. Superior LV reverse remodelling was observed in concordant LV leads compared with discordant LV leads [41 (73%) vs. 10 (43%); P = 0.01]. At 6-month follow-up, LV reverse dyssynchrony (reduction of anteroseptal to posterior delay ≥50%) using ST-RS imaging was similar in RV-A and RV-HS [25 (63%) vs. 24 (62%); P = 0.93]. More LV reverse dyssynchrony was found in concordant LV leads vs. discordant LV leads [39 (70%) vs. 10 (43%); P = 0.03]. A concordant LV lead was an independent predictor of LV reverse remodelling (odds ratio, 3.65; P = 0.01) and LV reverse dyssynchrony (odds ratio, 4.22; P = 0.02) 6 months after CRT. CONCLUSION: RV-A and RV-HS in CRT demonstrated similar LV reverse remodelling and LV reverse dyssynchrony at 6-month follow-up. Concordant LV leads provided superior LV reverse remodelling and LV reverse dyssynchrony.