Over the last few years, pacing of the conduction system (CSP) has emerged as the new standard pacing modality for bradycardia indications, allowing a more physiological ventricular activation compared to conventional right ventricular pacing. CSP has also emerged as an alternative modality to conventional biventricular pacing for the delivery of cardiac resynchronization therapy (CRT) in heart failure patients. However, if the initial clinical data seem to support this new physiological-based approach to CRT, the lack of large randomized studies confirming these preliminary results prevents CSP from being used routinely in clinical practice. Furthermore, concerns are still present regarding the long-term performance of pacing leads when employed for CSP, as well as their extractability. In this review article, we provide the state-of-the-art of CSP as an alternative to biventricular pacing for CRT delivery in heart failure patients. In particular, we describe the physiological concepts supporting this approach and we discuss the future perspectives of CSP in this context according to the implant techniques (His bundle pacing and left bundle branch area pacing) and the clinical data published so far.

The use of stress perfusion-cardiovascular magnetic resonance (CMR) imaging remains limited in patients with implantable devices. The primary goal of the study was to assess the safety, image quality, and the diagnostic value of stress perfusion-CMR in patients with MR-conditional transvenous permanent pacemakers (PPM) or implantable cardioverter-defibrillators (ICD). Consecutive patients with a transvenous PPM or ICD referred for adenosine stress-CMR were enrolled in this single-center longitudinal study. The CMR protocol was performed using a 1.5 T system according to current guidelines while all devices were put in MR-mode. Quality of cine, late-gadolinium-enhancement (LGE), and stress perfusion sequences were assessed. An ischemia burden of ≥ 1.5 segments was considered significant. We assessed the safety, image quality and the occurrence of interference of the magnetic field with the implantable device. In case of ischemia, we also assessed the correlation with the presence of significant coronary lesions on coronary angiography. Among 3743 perfusion-CMR examinations, 66 patients had implantable devices (1.7%). Image quality proved diagnostic in 98% of cases. No device damage or malfunction was reported immediately and at 1 year. Fifty patients were continuously paced during CMR. Heart rate and systolic blood pressure remained unchanged during adenosine stress, while diastolic blood pressure decreased (p = 0.007). Six patients (9%) had an ischemia-positive stress CMR and significant coronary stenoses were confirmed by coronary angiography in all cases. Stress perfusion-CMR is safe, allows reliable ischemia detection, and provides good diagnostic value.

Over the last decades, the implementation of new technology in cardiac pacemakers and defibrillators as well as the increasing life expectancy have been associated with a higher incidence of transvenous lead complications over time. Variable degrees of venous stenosis at the level of the subclavian vein, the innominate trunk and the superior vena cava are reported in up to 50% of implanted patients. Importantly, the number of implanted leads seems to be the main risk factor for such complications. Extraction of abandoned or dysfunctional leads is a potential solution to overcome venous stenosis in case of device upgrades requiring additional leads, but also, in addition to venous angioplasty and stenting, to reduce symptoms related to the venous stenosis itself, i.e., the superior vena cava syndrome. This review explores the role of transvenous lead extraction procedures as therapeutical option in case of central venous disorders related to transvenous cardiac leads. We also describe the different extraction techniques available and other clinical indications for lead extractions such as lead infections. Finally, we discuss the alternative therapeutic options for cardiac stimulation or defibrillation in case of chronic venous occlusions that preclude the implant of conventional transvenous cardiac devices.

Background: Predicting response to cardiac resynchronization therapy (CRT) remains a challenge. We evaluated the role of baseline QRS pattern to predict response in terms of improvement in biventricular ejection fraction (EF). Methods: Consecutive patients (pts) undergoing CRT implantation underwent radionuclide angiography at baseline and at mid-term follow-up. The relationship between baseline QRS pattern and mechanical dyssynchrony using phase analysis was evaluated. Changes in left and right ventricular EF (LVEF and RVEF) were analyzed with regard to baseline QRS pattern. Results: We enrolled 56 pts, 32 with left bundle branch block (LBBB), 4 with right bundle branch block (RBBB) and 20 with non-specific intraventricular conduction disturbance (IVCD). A total of 48 pts completed follow-up. LBBB pts had significantly greater improvement in LVEF compared to RBBB or non-specific IVCD pts (+9.6 ± 10.9% vs. +2.6 ± 7.6%, p = 0.003). Response (defined as ≥ 5% increase in LVEF) was observed in 68% of LBBB vs. 24% of non-specific IVCD pts (p = 0.006). None of the RBBB pts were responders. RVEF was significantly improved in LBBB (+5.0 ± 9.0%, p = 0.007), but not in non-specific IVCD and RBBB pts (+0.4 ± 5.8%, p = 0.76). At multivariate analysis, LBBB was the only predictor of LVEF response (OR, 7.45; 95% CI 1.80-30.94; p = 0.006), but not QRS duration or extent of mechanical dyssynchrony. Conclusions: Presence of a LBBB is a marker of a positive response to CRT in terms of biventricular improvement. Pts with non-LBBB pattern show significantly less benefit from CRT than those with LBBB.

Background: Device patients may require upgrade interventions from simpler to more complex cardiac implantable electronic devices. Prior to upgrading interventions, clinicians need to balance the risks and benefits of transvenous lead extraction (TLE), additional lead implantation or lead abandonment. However, evidence on procedural outcomes of TLE at the time of device upgrade is scarce. Methods: This is a post hoc analysis of the investigator-initiated multicenter Swiss TLE registry. The objectives were to assess patient and procedural factors influencing TLE outcomes at the time of device upgrades. Results: 941 patients were included, whereof 83 (8.8%) had TLE due to a device upgrade. Rotational mechanical sheaths were more often used in upgraded patients (59% vs. 42.7%, p = 0.015) and total median procedure time was longer in these patients (160 min vs. 105 min, p < 0.001). Clinical success rates of upgraded patients compared to those who received TLE due to other reasons were not different (97.6% vs. 93.0%, p = 0.569). Moreover, multivariable analysis showed that upgrade procedures were not associated with a greater risk for complications (HR 0.48, 95% confidence interval 0.14–1.57, p = 0.224; intraprocedural complication rate of upgraded patients 7.2% vs. 5.5%). Intraprocedural complications of upgraded patients were mostly associated with the implantation and not the extraction procedure (67% vs. 33% of complications). Conclusions: TLE during device upgrade is effective and does not attribute a disproportionate risk to the upgrade procedure.

Background: Identification of persistent AF (PsAF) patients who may be cured with stand‐alone pulmonary vein isolation (PVI) would allow more efficient ablation strategies. Intuitively, the benefit of PVI is expected to be lower when PVs are poorly connected, but this assumption has never been tested. Objective: Evaluate whether the circumferential extent of PV connections assessed pre‐ablation predicts the success rate of PVI. Methods: Consecutive patients with PsAF undergoing first ablation with stand‐alone PVI were included. The extent of PV electrical connection was assessed using a circular mapping catheter and graded as limited, moderate, or extensive, according to tertiles of the mean numbers of bipoles recording PV potentials along the circumference of each vein. Results: One hundred and forty‐eight patients were included (age 64 ± 9.7 years, PsAF duration 7.3 ± 7 months). After a mean follow‐up of 38.6 ± 7.8 months, freedom from arrhythmia recurrence after last PVI was significantly lower in patients with limited (38.6%), compared to moderate, and extensive PV connections (69.7% and 69%, respectively; p = 0.002). While redo PVI procedures did not significantly affect final ablation outcomes in patients with limited PV connections, a significant incremental arrhythmia‐free survival gain was observed with increasing extent of PV connections ( p < 0.01). Conclusions: The circumferential extent of PV connections is correlated to the success rate of PVI in patients with PsAF and may be a marker of the contribution of PVs to AF. The finding of limited PV connections may be used to select patients who may benefit from first‐line adjunctive ablation.