Long-Term Outcome of the First Completely Leadless Cardiac Resynchronization Therapy in the United States.

Completely leadless cardiac resynchronization therapy is feasible with the combination of Micra AV pacemaker (Medtronic Inc) and WiSE-CRT (EBR Inc) systems. Several reports have highlighted this combination in Europe. This case report presents a 1- year follow-up the first reported concomitant use of the leadless systems in the United States. (Level of Difficulty: Advanced.).

Biventricular endocardial pacing and left bundle branch area pacing for cardiac resynchronization: Mechanistic insights from electrocardiographic imaging, acute hemodynamic response, and magnetic resonance imaging.

BACKGROUND: Biventricular endocardial pacing (BiV-endo) has demonstrated superior cardiac resynchronization compared to conventional biventricular epicardial pacing (BiV-epi). Left bundle branch area pacing (LBBAP) may also achieve effective cardiac resynchronization therapy (CRT). OBJECTIVE: The purpose of this study was to compare the acute electrical and hemodynamic effects of BiV-epi, BiV-endo, and LBBAP delivered from the LV endocardium and to assess how myocardial scar affects response. METHODS: Eleven patients with heart failure and indications for CRT underwent a temporary pacing study with electrocardiographic imaging (ECGi) and hemodynamic assessment. BiV-endo was delivered by stimulation of the left ventricular (LV) lateral wall, and LBBAP was delivered by stimulation of the LV septum, at the site of a Purkinje potential. LV activation time (LVAT-95), LV dyssynchrony index (LVDI), biventricular activation time (BIVAT-90), and biventricular dyssynchrony index (BIVDI) were calculated. Myocardial scar was assessed using magnetic resonance imaging (MRI). RESULTS: The protocol was completed in 10 patients. Compared to BiV-epi (LVAT-95: 79.2 ± 13.1 ms; LVDI: 26.6 ± 3.4 ms) LV resynchronization was superior during BiV-endo (LVAT-95: 48.5 ± 14.9 ms; P = .001; LVDI: 16.6 ± 6.4 ms; P = .002) and LBBAP (LVAT-95: 48.9 ± 12.5 ms; P = .001; LVDI: 15.3 ± 3.4 ms; P = .001). Biventricular resynchronization was similarly superior during BiV-endo and LBBAP vs BiV-epi (BIVAT-90 and BIVDI; P <.05). The rate of acute hemodynamic responders was higher during BiV-endo (90%) and LBBAP (70%) vs BiV-epi (50%). The benefits of LBBAP (but not BiV-endo) on LV resynchronization were attenuated when septal scar was present in a subset of 8 patients who underwent MRI. CONCLUSION: Our findings suggest superior electrical resynchronization and a higher proportion of acute hemodynamic responders during BiV-endo and LBBAP compared to BiV-epi. Electrical resynchronization was similar between BiV-endo and LBBAP; however, septal scar seemed to attenuate response to LBBAP.

Feasibility of leadless left ventricular septal pacing with the WiSE-CRT system to target the left bundle branch area: A porcine model and multicenter patient experience.

BACKGROUND: The WiSE-CRT system delivers leadless endocardial left ventricular (LV) pacing to achieve cardiac resynchronization therapy. The electrode is conventionally placed on the lateral wall, but implanting on the LV septum may have advantages, including capture of the left bundle branch, and improved battery longevity owing to reduced distance from the transmitter. OBJECTIVE: The purpose of this study was to assess the feasibility of leadless LV septal pacing via the WiSE-CRT system. METHODS: Two pigs underwent electrode implantation on the LV septum with subsequent anatomical and histological examination. Eight patients underwent implantation of the WiSE-CRT system with deployment of the electrode on the LV septum via an interatrial transseptal approach. RESULTS: Deployment of the electrode on the LV septum was successful in both animals. Histological examination demonstrated electrode tines in close proximity to Purkinje tissue. WiSE-CRT implantation with an LV septal electrode was successful in all patients. Biventricular capture was confirmed, with a significant reduction in QRS duration (187.1 ± 33.8 ms vs 149.5 ± 15.7 ms; P = .009). Temporary LV pacing achieved further QRS reduction (139.8 ± 12.4 ms), and in 4 patients the peak LV activation time in lead V5/V6 was <90 ms, suggesting left bundle branch capture. At early follow-up, the median LV pacing percentage was 98.5% and 5 patients (62.5%) improved symptomatically. The transmitter-to-electrode distance was lower than the distance to the lateral wall during acoustic window screening (8.8 ± 1.6 cm vs 11.9 ± 1.5 cm; P = .002). CONCLUSION: Leadless LV septal pacing with the WiSE-CRT system to target the left bundle branch appears feasible. Further study is required to assess the efficacy and safety of this technique.

Pacing Optimized by Left Ventricular dP/dtmax.

Left ventricular (LV) dP/dtmax provides a sensitive measure of the acute hemodynamic response to cardiac resynchronization therapy (CRT) and can predict reverse remodeling on echocardiography. Its use to guide LV lead placement has been shown to improve outcomes in a multicenter randomized trial. Given the invasive protocol required for measurement, it is unlikely to be universally beneficial for patients undergoing CRT but may be useful for patients who do not respond to conventional CRT, or in those who have borderline indications or risk factors for non-response. In such cases, LV dP/dtmax may help guide LV lead placement, optimize device programming, and select the best alternative method of delivering CRT, such endocardial LV pacing or conduction system pacing.

A systemic review of endocardial left ventricular pacing.

BACKGROUND: Endocardial left ventricular pacing is an alternative technique used in cardiac resynchronization therapy (CRT), when placement of a left ventricular lead is not possible via the coronary sinus or in non-responders to conventional CRT. OBJECTIVES: To review the evidence regarding the efficacy and safety of endocardial left ventricular pacing. METHODS: Systematic research on Medline (PubMed), ClinicalTrials.gov and Embase with the terms "endocardial left ventricular pacing", "biventricular pacing" or "endocardial left pacing" was performed with the identification of 1038 results. Eleven studies with endocardial left ventricular pacing patients were included, independent of the technique being applied to naïve CRT patients or con non-responders to conventional CRT. The end-point of this analysis was the impact of endocardial left ventricular pacing techniques regarding New York Heart Association (NYHA) functional classification, left ventricular ejection fraction (LVEF) and QRS width, and the occurrence of complications Mean differences (MD) and confidence interval (CI) was used as a measurement of treatment. RESULTS: A total of 560 patients were included, with different techniques used (trans-atrial septal technique, trans-ventricular septal technique and transapical technique). Significant improvement was registered in NYHA class (MD 0.73, CI 0.48-0.98, p<0.00001, I2 = 87%), LVEF (MD -7.63, CI -9.93 - -5.33, p<0.00001, I2 = 69%) and QRS width (MD 29.25, CI 9.99-48.50, p<0.00001, I2 = 91%). Several complications were reported after the procedure, 11 pocket infections, 22 transient ischemic attacks, 18 ischemic strokes, 41 thromboembolic events, among other complications. The mortality rate during the follow-up was 20.54%. CONCLUSION: Left ventricular endocardial pacing is a feasible alternative to conventional CRT, with clinical, electrocardiographic and echocardiogrphic improvement. However, first data regarding this procedure was associated with significant complications rates.

European experience with a first totally leadless cardiac resynchronization therapy pacemaker system.

AIMS: Totally leadless cardiac resynchronization therapy (CRT) can be delivered with a combination of Micra and WiSE-CRT systems. We describe the technical feasibility and first insights into the safety and efficacy of this combination in European experience. METHODS AND RESULTS: Patients enrolled had indication for both Micra and WiSE-CRT systems because of heart failure related to high burden of pacing by a Micra necessitating system upgrade or inability to implant a conventional CRT system because of infectious or anatomical conditions. The endpoints of the study were technical success of WiSE-CRT implantation with right ventricle-synchonized CRT delivery, acute QRS duration reduction, and freedom from procedure-related major adverse events. All eight WiSE-CRT devices were able to detect the Micra pacing output and to be trained to deliver synchronous LV endocardial pacing. Acute QRS reduction following WiSE-CRT implantation was observed in all eight patients (mean QRS 204.38 ± 30.26 vs. 137.5 ± 24.75 mS, P = 0.012). Seven patients reached 6 months of follow-up. At 6 months after WiSE-CRT implantation, there was a significant increase in LV ejection fraction (28.43 ± 8.01% vs. 39.71 ± 11.89%; P = 0.018) but no evidence of LV reverse remodelling or improvement in New York Heart Association class. CONCLUSION: The Micra and the WiSE-CRT systems can successfully operate together to deliver total leadless CRT to a patient. Moreover, the WiSE-CRT system provides the only means to upgrade the large population of Micra patients to CRT capability without replacing the Micra. The range of application of this combination could broaden in the future with the upcoming developments of leadless cardiac pacing.

Caudocranial transseptal approach for placement of endocardial left ventricular leads.

Cardiac resynchronization therapy (CRT) is associated with improvement in the quality of life, hospitalization rates, and mortality in patients with left ventricular dysfunction and evidence of the right ventricle-left ventricle (RV-LV) desynchrony. Implant failure rates and patient outcomes have improved with the advent of quadripolar leads, yet alternatives to traditional coronary sinus (CS) LV lead placement is sought for in a subset of advanced heart failure patients with difficult CS anatomy, phrenic nerve stimulation or in nonresponders. Endocardial left ventricular pacing (EnLVP) in chronically anticoagulated patients has been reported as an alternative using different approaches, techniques, and tools with acceptable short and long term adverse events. We present a case of successful EnLVP achieved for CRT using standard techniques and commonly available tools in a patient on chronic direct oral anticoagulation with recurrent heart failure admissions who failed traditional epicardial LV pacing.

Femoral implantation and pull through as an adjunct to traditional methods in cardiac resynchronization therapy.

BACKGROUND: We have described the use of femoral access followed by pull through of the lead to a pectoral position to circumvent difficulty in implanting a left ventricular (LV) lead by standard methods. OBJECTIVE: The purpose of this study was to establish the effect of femoral implantation and pull through on the overall rate of success in percutaneous implantation of LV leads. METHODS: We collected data prospectively in all attempts at LV lead implantation from the time that we envisioned the femoral pull-through approach. RESULTS: In the 6 years to September 30, 2014, our group attempted to implant a new LV lead in 736 patients, including 16 who previously had failed attempts by other groups. A standard superior approach was successful in 726 of 731 patients (99.3%) in whom it was attempted. In 5 patients (0.7%), we failed to deliver a lead from a superior approach; in 5 of 16 patients, with previous failed attemtps (31%), we judged that those attempts had been exhaustive. In all 10 cases, LV lead placement was achieved from a femoral approach, with the procedure time being 186 ± 65 minutes. In the first case attempted, the pull through failed; the lead was tunneled to the pectoral generator. In 1 case, the coronary sinus was found to be occluded at the ostium: a transseptal approach was used with the subsequent pull through. No complication occurred. At 22.3 ± 18.5 months after the implantation, all systems implanted by a femoral approach continued to function. CONCLUSION: Used as an adjunct to standard methods, the femoral access and pull through method allows percutaneous LV lead placement in virtually all cases.