Extending multipoint pacing CRT battery longevity by swapping left ventricular pulse configurations.

PURPOSE: Cardiac resynchronization therapy (CRT) with left ventricular (LV) MultiPoint™ pacing (MPP) has been shown to improve CRT response by pacing two LV sites (LV1, LV2). While an additional LV pacing site reduces battery longevity, this cost can be minimized by leveraging an existing device-based capture management algorithm (LVCap™ Confirm). The purpose of this study was to evaluate the MPP battery longevity improvement achieved by configuring LV pacing sites to properly leverage LVCap Confirm. METHODS: Patients previously enrolled in the MORE-CRT MPP trial with existing MPP-enabled CRT-D devices (Abbott Quadra Assura MP™ CD3371-40QC, Quartet™ LV lead) underwent device interrogation. Device electrical characteristics and estimated battery longevities were compared for various MPP settings. RESULTS: At 2.1 ± 1.1 years post-implant, the estimated remaining battery longevity in 65 patients was 70 ± 14 months with MPP Off (LV pacing from minimum capture threshold). Enabling MPP with maximal anatomical separation between LV1 and LV2 cathodes reduced longevity by 15 ± 14%. However, swapping the LV1 and LV2 cathodes, such that the LV1 threshold was the higher of the two, allowed the device to take full advantage of the LVCap™ Confirm capture management algorithm, resulting in significantly lower longevity reduction of 9 ± 11% (p < 0.001). Ultimately, a mean MPP battery longevity improvement of 7.7 ± 10.3% (p < 0.001) was achieved by simply swapping LV1/LV2 configurations. CONCLUSIONS: By properly leveraging device-based capture management features, the impact of MPP on battery longevity can be significantly reduced.

Primary safety results from the LEADLESS Observational Study.

Aims: A prospective, single-arm, multicentre, post-market study was conducted to confirm the short-term safety of the Nanostim™ leadless pacemaker (LP). In this study, we report the primary results of the LEADLESS Observational Study. Methods and results: Subjects meeting VVIR pacemaker indications were enrolled and followed up after successful LP implantation, prior to discharge and post-implantation at 90 days, 180 days, and every 6 months thereafter for the assessment of adverse events. The primary safety endpoint was evaluated in terms of freedom from serious adverse device effects (SADEs) at 6 months in 300 subjects. Data for all enrolled subjects were also presented. A total of 470 subjects were enrolled (75.8 ± 13.1 years, 62.8% male). The study paused in April 2014 following the occurrence of perforation events that led to changes in the protocol and investigator training. Freedom from SADEs, evaluated in 300 subjects enrolled post-pause, was 94.6% (95% confidence interval 91.0-97.2%) and demonstrated non-inferiority to a performance goal of 86% (P < 0.0001). Eighteen SADEs were observed in 16 (5.3%) subjects. The most frequently occurring events were cardiac perforation (1.3%), device dislodgement (0.3%), and vascular complications (1.3%). In the 470 subjects, 34 similar SADEs were observed in 31 (6.6%) subjects. After stratifying the results in relation to the study pause, there was a statistically significant difference in the final LP location (septum vs. apex) (P < 0.0001) and the number of repositioning attempts (<2 vs. ≥2) (P = 0.05) and a decreasing trend in the rates of cardiac perforation and device dislodgement. Conclusion: The primary safety endpoint at 6 months was successfully met for the Nanostim LP. The occurrence of cardiac perforation and device dislodgement declined after changes following the study pause.

Improvement in hemodynamic response using a quadripolar LV lead.

BACKGROUND: The Quartet quadripolar lead (St. Jude Medical Inc., St. Paul, MN, USA) offers 10 different left ventricle pacing configurations that may further influence hemodynamic parameters compared to traditional bipolar pacing configurations. The purpose of this study was to evaluate whether pacing from additional quadripolar lead vectors could enhance cardiac output (CO). METHODS: For each patient, CO was measured in "no-pacing" and in all the 10 configurations available, within 7 days of implantation of the device. Tip-ring, tip-right ventricular coil (RVC), and ring-RVC vectors were considered as traditional vectors. The seven additional configurations available in the quadripolar lead were considered as nontraditional vectors. CO was measured by ECHO. The best configuration was defined as the one presenting the highest CO measurement within configurations, which have a capture threshold <3 V and a safety margin between the capture and the phrenic nerve stimulation thresholds. RESULTS: Fifty-one standard cardiac resynchronization therapy patients were enrolled. The mean of each patient's best CO obtained with traditional vectors was higher than the baseline nonpaced CO (4.16 L/min vs 3.64 L/min). The mean of each patient's best CO, including all 10 available configurations, was also higher than the baseline nonpaced CO (4.33 L/min vs 3.64 L/min). In addition, the mean of each patient's best CO obtained with the best configuration available through a quadripolar lead was better than the mean of each patient's best CO obtained with a traditional configuration. In 53% of patients, the best CO was obtained with a nontraditional vector unique to the quadripolar lead. CONCLUSIONS: A quadripolar lead offers multiple additional pacing options to increase CO acutely compared to conventional bipolar leads.