The evolving state of cardiac resynchronization therapy and conduction system pacing: 25 years of research at EP Europace journal

LV cathode position in CRT recipients: How can we benefit from CMR?

BACKGROUND

Left ventricular lead positioning represents a key step in CRT optimization. However, evidence for its guidance based on specific topographical factors and related imaging techniques is sparse.

OBJECTIVE

To analyze reverse remodeling (RR) and clinical events in CRT recipients based on LV cathode (LVC) position relative to latest mechanical activation (LMA) and scar as determined by cardiac magnetic resonance (CMR).

METHODS

This is a retrospective single-center study of 68 consecutive Q-LV-guided CRT-D and CRT-P recipients. Through CMR-based 3D reconstructions overlayed on fluoroscopy images, LVCs were stratified as concordant, adjacent, or discordant to LMA (3 segments with latest and greatest radial strain) and scar (segments with >50% scar transmurality). The primary endpoint of RR (expressed as percentage ESV change) and secondary composite endpoint of HF hospitalizations, LVAD/heart transplant, or cardiovascular death were compared across categories.

RESULTS

LVC proximity to LMA was associated with a progressive increase in RR (percentage ESV change: concordant -47.0 ± 5.9%, adjacent -31.4 ± 3.1%, discordant +0.4 ± 3.7%), while proximity to scar was associated with sharply decreasing RR (concordant +10.7 ± 12.9%, adjacent +0.3 ± 5.3%, discordant -31.3 ± 4.4%, no scar -35.4 ± 4.8%). 4 integrated classes of LVC position demonstrated a significant positive RR gradient the more optimal the category (class I -47.0 ± 5.9%, class II -34.9 ± 2.8%, class III -5.5 ± 4.3%, class IV + 3.4 ± 5.2%). Freedom from composite secondary endpoint of HF hospitalization, LVAD/heart transplant, or cardiovascular death confirmed these trends demonstrating significant differences across both integrated as well as individual LMA and scar categories.

CONCLUSION

Integrated CMR-determined LVC position relative to LMA and scar stratifies response to CRT.

Selection of candidates for cardiac resynchronization therapy and implantation management: an Italian survey promoted by the Italian Association of Arrhythmology and Cardiac Pacing

BACKGROUND

Cardiac resynchronization therapy (CRT) represents an effective heart failure treatment, associated with reduction in mortality and heart failure hospitalizations. This Italian survey aimed to address relevant CRT issues.

METHODS

An online survey was administered to AIAC members.

RESULTS

One hundred and five electrophysiologists participated, with a median of 40 (23-70) CRT implantations/year (33% in high-volume centres). Forty-five percent of respondents (especially working in high-volume centres) reported an increase in CRT implantations in the last 2 years, in 16% a decrease, and in 38% CRT remained stable. Seventy-five percent of respondents implanted CRT only in patients with European Heart Rhythm Association (EHRA) class I indications. All operators collected ECG and echocardiography before implantation. Eighty-five percent of respondents selected coronary sinus target vein empirically, whereas 10% used mechanical and/or electrical delay techniques. Physicians working in high-volume centres reported a lower failure rate compared with others (16 vs. 34%; P = 0.03). If the coronary sinus lead could not be positioned in the target branch, 80% placed it in another vein, whereas 16% opted for a surgical approach or for conduction system pacing (CSP). Eighty percent accomplished CRT optimization in all patients, 17% only in nonresponders. Regarding anticoagulation, high agreement with EHRA guidelines emerged.

CONCLUSION

CRT represents a valid therapeutic option in heart failure treatment. Nowadays, CRT implantations remain stable and are mainly performed in patients with class I indications. ECG remains the preferred tool for patient selection, whereas imaging is increasingly used to determine the left pacing target area. In most patients, the left ventricular lead can be successfully positioned in the target vein, but in some cases, the result can be unsatisfactory; however, the decision to explore alternative resynchronization approaches is rarely pursued.

Clinical significance and prognostic value of right bundle branch block in permanent pacemaker patients

AIMS

In patients undergoing pacemaker implantation with no prior history of heart failure (HF), the presence of left bundle branch block (LBBB) has been identified as an independent predictor of HF-related death or hospitalization, while the prognostic significance of right bundle branch block (RBBB) remains uncertain. We aimed to assess the long-term risk of all-cause mortality in patients with a standard indication for permanent pacing and normal or moderately depressed left ventricular function when RBBB is detected at the time of implantation.

METHODS

We retrospectively enrolled 1348 consecutive patients who had undergone single- or dual-chamber pacemaker implantation at the study center, from January 1990 to December 2022. Patients with a left ventricular ejection fraction ≤35% or a prior diagnosis of HF were excluded.

RESULTS

The baseline 12-lead electrocardiogram revealed an RBBB in 241 (18%) and an LBBB in 98 (7%) patients. During a median follow-up of 65 [25th-75th percentile: 32-117] months, 704 (52%) patients died. The combined endpoint of cardiovascular death or HF hospitalization was reached by 173 (13%) patients. On multivariate analysis, RBBB was confirmed as an independent predictor of death [hazard ratio, 1.33; 95% confidence interval (CI), 1.09-1.63; P  = 0.005]. However, when considering the combined endpoint of cardiovascular death and HF hospitalization, this endpoint was independently associated with LBBB (hazard ratio, 2.13; 95% CI, 1.38-3.29; P  < 0.001), but not with RBBB.

CONCLUSION

In patients with standard pacemaker indications and normal or moderately depressed left ventricular function, the presence of basal RBBB was an independent predictor of mortality. However, it was not associated with the combined endpoint of cardiovascular death and HF hospitalization.

[Treatment with cardiac electronic implantable devices]

Cardiac device therapy provides not only treatment options for bradyarrhythmia but also advanced treatment for heart failure and preventive measures against sudden cardiac death. In heart failure treatment it enables synergistic reverse remodelling and reduces pharmacological side effects. Cardiac resynchronization therapy (CRT) has revolutionized the treatment of reduced left ventricular ejection fraction (LVEF) and left bundle branch block by decreasing the mortality and morbidity with improvement of the quality of life and resilience. Conduction system pacing (CSP) as an alternative method of physiological stimulation can improve heart function and reduce the risk of pacemaker-induced cardiomyopathy. Leadless pacers and subcutaneous/extravascular defibrillators offer less invasive options with lower complication rates. The prevention of infections through preoperative and postoperative strategies enhances the safety of these therapies.

Cardiac Resynchronization Therapy for Patients With Mild to Moderately Reduced Ejection Fraction and Left Bundle Branch Block

BACKGROUND

It is unknown whether cardiac resynchronization therapy (CRT) would improve or halt the progression of heart failure (HF) in patients with mild to moderately reduced ejection fraction (HFmmrEF) and left bundle branch block (LBBB).

OBJECTIVE

This study aimed to investigate the outcomes of CRT in patients with HFmmrEF and left ventricular conduction delay.

METHODS

A prospective, randomized clinical trial sponsored by the National Heart, Lung, and Blood Institute included 76 patients who met the study inclusion criteria (left ventricular ejection fraction [LVEF] of 36%-50% and LBBB). Patients received CRT-pacemaker and were randomized to CRT-OFF (right ventricular pacing 40 beats/min) or CRT-ON (biventricular pacing 60-150 beats/min). At a 6-month follow-up, pacing programming was changed to the opposite settings. New York Heart Association class, N-terminal pro-brain natriuretic peptide levels, and echocardiographic variables were collected at baseline, 6 months, and 12 months. The primary study end point was the left ventricular end-systolic volume (LVESV) change from baseline, and the primary randomized comparison was the comparison of 6-month to 12-month changes between randomized groups.

RESULTS

The mean age of the patients was 68.4 ± 9.8 years (male, 71%). Baseline characteristics were similar between the 2 randomized groups (all P > .05). In patients randomized to CRT-OFF first, then CRT-ON, LVESV was reduced from baseline only after CRT-ON (baseline, 116.1 ± 36.5 mL; CRT-ON, 87.6 ± 26.0 mL; P < .0001). The randomized analysis of LVEF showed a significantly better change from 6 to 12 months in the OFF-ON group (P = .003). LVEF was improved by CRT (baseline, 41.3% ±.7%; CRT-ON, 46.0% ± 8.0%; P = .002). In patients randomized to CRT-ON first, then CRT-OFF, LVESV was reduced after both CRT-ON and CRT-OFF (baseline, 109.8 ± 23.5 mL; CRT-ON, 91.7 ± 30.5 mL [P < .0001]; CRT-OFF, 99.3 ± 28.9 mL [P = .012]). However, the LVESV reduction effect became smaller between CRT-ON and CRT-OFF (P = .027). LVEF improved after both CRT-ON and CRT-OFF (baseline, 42.7% ± 4.3%; CRT-ON, 48.5% ± 8.6% [P < .001]; CRT-OFF, 45.9% ± 7.7% [P = .025]).

CONCLUSION

CRT for patients with HFmmrEF significantly improves LVEF and ventricular remodeling after 6 months of CRT. The study provides novel evidence that early CRT benefits patients with HFmmrEF with LBBB.

Cardiac magnetic resonance-derived myocardial scar is associated with echocardiographic response and clinical prognosis of left bundle branch area pacing for cardiac resynchronization therapy

AIMS

Left bundle branch area pacing (LBBAP) is a novel approach for cardiac resynchronization therapy (CRT), but the impact of myocardial substrate on its effect is poorly understood. This study aims to assess the association of cardiac magnetic resonance (CMR)-derived scar burden and the response of CRT via LBBAP.

METHODS AND RESULTS

Consecutive patients with CRT indications who underwent CMR examination and successful LBBAP-CRT were retrospectively analysed. Cardiac magnetic resonance late gadolinium enhancement was used for scar assessment. Echocardiographic reverse remodelling and composite outcomes (defined as all-cause death or heart failure hospitalization) were evaluated. The echocardiographic response was defined as a ≥15% reduction of left ventricular end-systolic volume. Among the 54 patients included, LBBAP-CRT resulted in a 74.1% response rate. The non-responders had higher global, septal, and lateral scar burden (all P < 0.001). Global, septal, and lateral scar percentage all predicted echocardiographic response [area under the curve (AUC): 0.857, 0.864, and 0.822; positive likelihood ratio (+LR): 9.859, 5.594, and 3.059; and negative likelihood ratio (-LR): 0.323, 0.233, and 0.175 respectively], which was superior to QRS morphology criteria (Strauss left bundle branch abnormality: AUC: 0.696, +LR 2.101, and -LR 0.389). After a median follow-up time of 20.3 (11.5-38.7) months, higher global, lateral and septal scar burdens were all predictive of the composite outcome (hazard ratios: 4.996, 7.019, and 4.741, respectively; P's < 0.05).

CONCLUSION

Lower scar burden was associated with higher response rate of LBBAP-CRT. The pre-procedure CMR scar evaluation provides further useful information to identify potential responders and clinical outcomes.

Length of hospital stay for elective electrophysiological procedures: a survey from the European Heart Rhythm Association

AIMS

Electrophysiological (EP) operations that have traditionally involved long hospital lengths of stay (LOS) are now being undertaken as day case procedures. The coronavirus disease-19 pandemic served as an impetus for many centres to shorten LOS for EP procedures. This survey explores LOS for elective EP procedures in the modern era.

METHODS AND RESULTS

An online survey consisting of 27 multiple-choice questions was completed by 245 respondents from 35 countries. With respect to de novo cardiac implantable electronic device (CIED) implantations, day case procedures were reported for 79.5% of implantable loop recorders, 13.3% of pacemakers (PMs), 10.4% of implantable cardioverter defibrillators (ICDs), and 10.2% of cardiac resynchronization therapy (CRT) devices. With respect to CIED generator replacements, day case procedures were reported for 61.7% of PMs, 49.2% of ICDs, and 48.2% of CRT devices. With regard to ablations, day case procedures were reported for 5.7% of atrial fibrillation (AF) ablations, 10.7% of left-sided ablations, and 17.5% of right-sided ablations. A LOS ≥ 2 days for CIED implantation was reported for 47.7% of PM, 54.5% of ICDs, and 56.9% of CRT devices and for 54.5% of AF ablations, 42.2% of right-sided ablations, and 46.1% of left-sided ablations. Reimbursement (43-56%) and bed availability (20-47%) were reported to have no consistent impact on the organization of elective procedures.

CONCLUSION

There is a wide variation in the LOS for elective EP procedures. The LOS for some procedures appears disproportionate to their complexity. Neither reimbursement nor bed availability consistently influenced LOS.