Left bundle branch pacing vs ventricular septal pacing for cardiac resynchronization therapy.

Background: The outcomes of left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP) in patients with heart failure remain to be learned. Objective: The objective of this study was to assess the echocardiographic and clinical outcomes of LBBP, LVSP, and deep septal pacing (DSP). Methods: This retrospective study included patients who met the criteria for cardiac resynchronization therapy (CRT) and underwent attempted LBBP in 5 Mayo centers. Clinical, electrocardiographic, and echocardiographic data were collected at baseline and follow-up. Results: A total of 91 consecutive patients were included in the study. A total of 52 patients had LBBP, 25 had LVSP, and 14 had DSP. The median follow-up duration was 307 (interquartile range 208, 508) days. There was significant left ventricular ejection fraction (LVEF) improvement in the LBBP and LVSP groups (from 35.9 ± 8.5% to 46.9 ± 10.0%, P < .001 in the LBBP group; from 33.1 ± 7.5% to 41.8 ± 10.8%, P < .001 in the LVSP group) but not in the DSP group. A unipolar paced right bundle branch block morphology during the procedure in lead V1 was associated with higher odds of CRT response. There was no significant difference in heart failure hospitalization and all-cause deaths between the LBBP and LVSP groups. The rate of heart failure hospitalization and all-cause deaths were increased in the DSP group compared with the LBBP group (hazard ratio 5.10, 95% confidence interval 1.14-22.78, P = .033; and hazard ratio 7.83, 95% confidence interval 1.38-44.32, P = .020, respectively). Conclusion: In patients undergoing CRT, LVSP had comparable CRT outcomes compared with LBBP.

Electrocardiographic spiked-helmet sign in critical non-cardiac illness.

The spiked-helmet sign (SHS) is an electrocardiographic finding characterised by a distinctive pattern associated with critical illness, resolving once the clinical condition improves. While the underlying mechanism remains uncertain, different mechanisms have been proposed to account for these findings including changes in intrathoracic or intra-abdominal pressures, transient compression of the coronary arteries, repolarisation abnormalities and electromechanical artefacts. We describe the development of the SHS in a patient with underlying left bundle branch pacing following the development of respiratory failure due to haemoptysis and review proposed mechanisms for its pathophysiology.

Catheter ablation of atrial fibrillation in patients with and without hypertrophic cardiomyopathy: systematic review and meta-analysis.

BACKGROUND: Atrial fibrillation (AF) is common in hypertrophic cardiomyopathy (HCM). There is limited data regarding the outcomes of AF catheter ablation in HCM patients. In this study, we aimed to synthesize all available evidence on the effectiveness of ablation of AF in patients with HCM compared to those without HCM. METHODS AND RESULTS: We systematically reviewed bibliographic databases to identify studies published through February 2023. We included cohort studies with available quantitative information on rates of recurrent atrial arrhythmias, anti-arrhythmic drug (AAD) therapy, and repeat ablation procedures after initial AF ablation in patients with vs without HCM. Estimates were combined using random-effects meta-analysis models and reported as risk ratios (RR) and 95% confidence intervals (CI). Eight studies were included in quantitative synthesis (262 HCM and 642 non-HCM patients). During median follow-up 13-54 months across studies, AF recurrence rates ranged from 13.3% to 92.9% in HCM and 7.6% to 58.8% in non-HCM patients. The pooled RR for recurrent atrial arrhythmia after the first AF ablation in HCM patients compared to non-HCM controls was 1.498 (95% CI = 1.305-1.720; P < 0.001). During follow-up, HCM patients more often required AAD therapy (RR = 2.844; 95% CI = 1.713-4.856; P < 0.001) and repeat AF ablation (RR = 1.544; 95% CI = 1.070-2.228; P = 0.02). The pooled RR for recurrent atrial arrhythmias after the last AF ablation was higher in patients with HCM than those without HCM (RR = 1.607; 95% CI = 1.235-2.090; P < 0.001). CONCLUSIONS: Compared to non-HCM patients, those with HCM had higher rates of recurrent atrial arrhythmias, AAD use, and need for repeat AF ablation after initial ablation of AF.

Ventricular arrhythmias in patients with prior aortic valve intervention: Characteristics, ablation and outcomes.

INTRODUCTION: Data regarding ventricular tachycardia (VT) or premature ventricular complex (PVC) ablation in patients with aortic valve (AV) intervention (AVI) is limited. Catheter ablation (CA) can be challenging given perivalvular substrate in the setting of prosthetic valves. We sought to investigate the characteristics, safety, and outcomes of CA in patients with prior AVI and ventricular arrhythmias (VA). METHODS: We identified consecutive patients with prior AVI (replacement or repair) who underwent CA for VT or PVC between 2013 and 2018. We investigated the mechanism of arrhythmia, ablation approach, perioperative complications, and outcomes. RESULTS: We included 34 patients (88% men, mean age 64 ± 10.4 years, left ventricular (LV) ejection fraction 35.2 ± 15.0%) with prior AVI who underwent CA (22 VT; 12 PVC). LV access was obtained through trans-septal approach in all patients except one patient who had percutaneous transapical access. One patient had combined retrograde aortic and trans-septal approach. Scar-related reentry was the dominant mechanism of induced VTs. Two patients had bundle branch reentry VTs. In the VT group, substrate mapping demonstrated heterogeneous scar that involved the peri-AV area in 95%. Despite that, the site of successful ablation included the periaortic region only in 6 (27%) patients. In the PVC group, signal abnormalities consistent with scar in the periaortic area were noted in 4 (33%) patients. In 8 (67%) patients, the successful site of ablation was unrelated to the periaortic area. No procedure-related complications occurred. The survival and recurrence-free survival rate at 1 year tended to be lower in VT group than in PVC group (p = .06 and p = .05, respectively) with a 1-year recurrence-free survival rate of 52.8% and 91.7%, respectively. No arrhythmia-related death was documented on long-term follow-up. CONCLUSION: CA of VAs can be performed safely and effectively in patients with prior AVI.

Characterization of ventricular arrhythmias and sudden cardiac death in subjects with mitral valve prolapse and mitral annular disjunction.

Sudden cardiac death is reported as the leading cause of mortality in developed nations. Arrhythmic mitral valve disease, encompassing mitral valve prolapse and/or mitral annular disjunction, is thought to be responsible in a sizable portion of these deaths. Despite this evidence, there are no reliable methods or clinically useful risk stratification schemes to determine which group of patients are at higher risk or may benefit from interventions such as catheter ablation or prophylactic implantation of a defibrillator. The reasons for this lack of guidance include our incomplete understanding of the mechanisms of ventricular arrhythmias and the fact that mitral valve prolapse and disjunction are frequently diagnosed, yet carry an overall low risk of sudden cardiac death. This heterogeneity makes the development of a reliable prediction model based on the presence of common risk factors very difficult. In this review, we summarize the relevant literature regarding the epidemiology, diagnosis, pathophysiology, and management of mitral valve prolapse and mitral annular disjunction and elucidate their role in sudden cardiac death.

Effects of Pulsed Electric Fields on the Coronary Arteries in Swine.

BACKGROUND: Previous animal studies have shown no significant vascular injury from pulsed electrical field (PEF) ablation. We sought to assess the effect of PEF on swine coronary arteries. METHODS: We performed intracoronary and epicardial (near the coronary artery) PEF ablations in swine pretreated with dual antiplatelet and antiarrhythmic therapy. Intracoronary PEF was delivered using MapiT catheters (Biotronik, Berlin), whereas epicardial PEF was delivered using EPT catheters (Boston Scientific, MA). PEF pulse duration was microseconds (Nanoknife 3.0, Angio Dynamics, NY) or nanoseconds (CellFX, Pulse Biosciences, CA). RESULTS: We performed 39 intracoronary ablations in 10 swine and 20 epicardial-pericoronary ablations in 4 separate swine. Intracoronary PEF was delivered at higher energy compared with epicardial PEF (46 [interquartile range, IQR 20-85] J versus 10 [IQR 10-11] J, P < 0.01). Reversible coronary spasm occurred in 49% intracoronary ablations and 45% epicardial ablations (P=0.80). At the end study, fixed coronary stenosis was demonstrated in 44% intracoronary ablations (80% for microsecond PEF and 18% for nanosecond PEF) and 0% epicardial ablations. Visible hemorrhagic and/or fibrotic myocardial lesions were observed at necropsy with similar frequency between intracoronary and epicardial PEF (45% versus 50%, P=0.70). Nanosecond PEF (49 ablations in 11 swine), when compared with microsecond PEF (10 intracoronary ablations in 3 swine), resulted in lower energy delivery (21 [IQR 10-46] J versus 129 [IQR 24-143] J, P=0.03) and less incidence of fixed coronary stenosis (18% versus 80%, P=0.04). CONCLUSIONS: In the swine model, intracoronary PEF resulted both in significant coronary spasm and fixed coronary stenosis. Epicardial PEF, delivered at lower energy, resulted in reversible spasm but no fixed coronary stenosis.

Substrate Characterization and Outcomes of Catheter Ablation of Ventricular Arrhythmias in Patients With Mitral Annular Disjunction.

BACKGROUND: Mitral annular disjunction (MAD) has recently been recognized as an arrhythmogenic entity. Data on the electrophysiological substrate as well as the outcomes of catheter ablation of ventricular arrhythmias in patients with MAD is limited. METHODS: Forty patients with MAD (mean age 47±15 years; 70% female) underwent catheter ablation for ventricular arrhythmias. Detailed clinical, electrocardiographic, cardiac imaging, and procedural data were collected. Clinical outcomes were compared between patients who had substrate modification in the MAD area and those who did not. RESULTS: Twenty-three (57.5%) patients had ablation for premature ventricular contractions, 10 (25%) patients for sustained ventricular tachycardia, and 7 (17.5%) patients for premature ventricular contraction-triggered ventricular fibrillation. Mean end-systolic MAD length was 10.58±3.49 mm on transthoracic echocardiography. Seventeen (42.5%) patients had preprocedural cardiac magnetic resonance imaging, and 5 (29%) patients had late gadolinium enhancement. Among the 18 (45%) patients who had abnormal local electrograms (low voltage, long-duration, fractionated, isolated mid-diastolic potentials) during electroanatomical mapping, 10 (25%) patients had abnormal electrograms in the anterolateral mitral annulus and/or MAD area. Substrate modification was performed in 10 (25%) patients. Catheter ablation was acutely successful in 36 (90%) patients (elimination of premature ventricular contraction or noninducibility of ventricular tachycardia). After a median follow-up duration of 54.08 (interquartile range, 10.67-89.79) months, premature ventricular contraction burden decreased from a median of 9.75% (interquartile range, 3.25-14) before the ablation to a median of 4% (interquartile range, 1-7.75) after the ablation (P=0.03 [95% CI, 0.055-6.5]). Eight (20.5%) patients had repeat ablation for ventricular arrhythmias. Substrate modification of the MAD was associated with a trend toward lower rates of repeat ablation (0% versus 26.7%; P=0.16). CONCLUSIONS: Patients with MAD have a complex arrhythmogenic substrate, and catheter ablation is effective in reducing recurrence of ventricular arrhythmias. Substrate mapping and ablation may be considered in these patients.

Ventricular nanosecond pulsed electric field delivery using active fixation leads: a proof-of-concept preclinical study.

BACKGROUND: Mid-myocardial ventricular arrhythmias are challenging to treat. Cardiac electroporation via pulsed electric fields (PEFs) offers significant promise. We therefore tested PEF delivery using screw-in pacemaker leads as proof-of-concept. METHODS: In 5 canine models, we applied nanosecond PEF (pulse width 300 ns) across the right ventricular (RV) septum using a single lead bipolar configuration (n = 2) and between two leads (n = 3). We recorded electrograms (EGMs) prior to, immediately post, and 5 min after PEF. Cardiac magnetic resonance imaging (cMRI) and histopathology were performed at 2 weeks and 1 month. RESULTS: Nanosecond PEF induced minimal extracardiac stimulation and frequent ventricular ectopy that terminated post-treatment; no canines died with PEF delivery. With 1 lead, energy delivery ranged from 0.64 to 7.28 J. Transient ST elevations were seen post-PEF. No myocardial delayed enhancement (MDE) was seen on cMRI. No lesions were noted on the RV septum at autopsy. With 2 leads, energy delivery ranged from 56.3 to 144.9 J. Persistent ST elevations and marked EGM amplitude decreases developed post-PEF. MDE was seen along the septum 2 weeks and 1 month post-PEF. There were discrete fibrotic lesions along the septum; pathology revealed dense connective tissue with < 5% residual cardiomyocytes. CONCLUSIONS: Ventricular electroporation is feasible and safe with an active fixation device. Reversible changes were seen with lower energy PEF delivery, whereas durable lesions were created at higher energies. Central illustration: pulsed electric field delivery into ventricular myocardium with active fixation leads.

Cardiac ablation with pulsed electric fields: principles and biophysics.

Pulsed electric fields (PEFs) have emerged as an ideal cardiac ablation modality. At present numerous clinical trials in humans are exploring PEF as an ablation strategy for both atrial and ventricular arrhythmias, with early data showing significant promise. As this is a relatively new technology there is limited understanding of its principles and biophysics. Importantly, PEF biophysics and principles are starkly different to current energy modalities (radiofrequency and cryoballoon). Given the relatively novel nature of PEFs, this review aims to provide an understanding of the principles and biophysics of PEF ablation. The goal is to enhance academic research and ultimately enable optimization of ablation parameters to maximize procedure success and minimize risk.

Regional and Temporal Variation of Ventricular and Conduction Tissue Activity During Ventricular Fibrillation in Canines.

[Figure: see text].

Characteristics and Long-Term Outcomes of Patients With Prior Coronary Artery Bypass Grafting Undergoing Primary Percutaneous Coronary Intervention for ST-Segment Elevation Myocardial Infarction.

Limited data are available on characteristics and long-term outcomes of patients with coronary artery bypass grafts (CABG) undergoing primary percutaneous coronary intervention for ST-elevation myocardial infarction (STEMI). Between January 2000 to December 2014, we identified STEMI patients with prior CABG undergoing primary percutaneous coronary intervention from 3 sites. Kaplan-Meier methods to estimate survival and major adverse cardiac events (MACE) were employed and compared to a propensity matched cohort of non-CABG STEMI patients. Independent predictors of outcomes were analyzed with Cox modeling. Of the 3,212 STEMI patients identified, there were 296 (9.2%) CABG STEMI patients, having nearly similar frequencies of culprit graft (47.6%) versus culprit native (52.4%) as the infarct-related artery (IRA). At 10 years, the adjusted survival was 44% in CABG STEMI versus 55% in non-CABG STEMI (HR 1.26; 95%CI 0.86 to 1.87; p = 0.72). Survival free of MACE was lower for CABG STEMI (graft IRA, 37%; native IRA, 46%) as compared to non-CABG STEMI controls (63%) (p = 0.02). Neither CABG history nor IRA (native vs graft) was independently associated with death or MACE in multivariable analysis. Temporal trends showed no significant change in death or MACE rates of CABG STEMI patients over time. In conclusion, long term survival of CABG STEMI patients is not significantly different than matched STEMI patients without prior CABG; however, CABG STEMI patients were at significantly higher risk for MACE events.

Left ventricular pacing induced polymorphic ventricular tachycardia via the adaptive left ventricle pacing algorithm.

Providers should be aware of the possibility of cardiac resynchronization therapy-related proarrhythmia which could be life-threatening. His-bundle pacing may serve as an alternative, more physiological, option in the management as it preserves the normal sequence of depolarization from the septum to the lateral wall, and from endocardium to epicardium.

Catheter ablation for treatment of atrial fibrillation in patients with heart failure with reduced ejection fraction: A systematic review and meta-analysis.

BACKGROUND: Atrial fibrillation (AF) among patients with heart failure with reduced ejection fraction (HFrEF) is associated with adverse clinical outcomes. Our primary aim was to evaluate patient-centered outcomes and surrogate outcomes following catheter ablation (CA) of AF among patients with HFrEF compared to standard medical therapy with or without device therapy (atrioventricular node ablation and cardiac resynchronization therapy). METHODS: A systematic literature review was performed limiting our searches to randomized control trials reporting outcomes of CA compared to standard medical therapy with or without device therapy were included. Patient-centered outcomes were relative reduction in all-cause mortality, heart failure readmissions, and recurrence of AF. Surrogate outcomes of interest were change in ejection fraction, change in peak oxygen consumption, reduction in brain natriuretic peptide levels, change in 6-minute walk distance, and change in Minnesota living with heart failure score. RESULTS: Seven randomized control trials (Patient n = 721) met our inclusion criteria. All trials used radiofrequency energy for CA of AF. CA for AF was associated with significantly lower all-cause mortality (Risk ratio [RR] = 0.52, 95% confidence interval [CI] = 0.35-0.76, P = 0.001, I 2 = 0%), lower rate of heart failure readmission (RR = 0.58, 95% CI = 0.46-0.74, P < 0.001, I 2 = 0%) and lower rate of AF recurrence (RR = 0.33, 95% CI = 0.22-0.50, P < 0.001, I 2 = 68%) as compared to standard medical therapy. Surrogate outcomes showed a similar benefit favoring CA. CONCLUSION AND RELEVANCE: Catheter ablation for AF in HFrEF is associated with improvement in patient-centered outcomes and surrogate outcomes when compared to standard medical therapy with or without device therapy.

Impact of Physiologic Pacing Versus Right Ventricular Pacing Among Patients With Left Ventricular Ejection Fraction Greater Than 35%: A Systematic Review for the 2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society.

BACKGROUND: It is unclear whether physiologic pacing by either cardiac biventricular pacing (BiVP) or His bundle pacing (HisBP) may prevent adverse structural and functional consequences known to occur among some patients who receive right ventricular pacing (RVP). AIM: Our analysis sought to review existing literature to determine if BiVP and/or HisBP might prevent adverse remodeling and be associated with structural, functional, and clinical advantages compared with RVP among patients without severe left ventricular dysfunction (>35%) who required permanent pacing because of heart block. METHODS: A literature search was conducted using MEDLINE (through PubMed) and Embase to identify randomized trials and observational studies comparing the effects of BiVP or HisBP versus RVP on measurements of left ventricular dimensions, left ventricular ejection fraction (LVEF), heart failure functional classification, quality of life, 6-minute walk, hospitalizations, and mortality. Data from studies that met the appropriate population, intervention, comparator, and outcomes of interest were abstracted for meta-analysis. Studies that reported pooled outcomes among patients with LVEF both above and below 35% could not be included in the meta-analysis because of strict relationships with industry procedures that preclude retrieval of industry-retained unpublished data on the subset of patients with preserved left ventricular function. RESULTS: Evidence from 8 studies, including a total of 679 patients meeting the prespecified criteria for inclusion, was identified. Results were compared for BiVP versus RVP, HisBP versus RVP, and BiVP+HisBP versus RVP. Among patients who received physiologic pacing with either BiVP or HisBP, the LV end-diastolic and end-systolic volumes were significantly lower (mean duration of follow-up: 1.64 years; -2.77 mL [95% CI -4.37 to -1.1 mL]; p=0.001; and -7.09 mL [95% CI -11.27 to -2.91; p=0.0009) and LVEF remained preserved or increased (mean duration of follow-up: 1.57 years; 5.328% [95% CI: 2.86%-7.8%; p<0.0001). Data on clinical impact such as functional status and quality of life were not definitive. Data on hospitalizations were unavailable. There was no effect on mortality. Several studies stratified results by LVEF and found that patients with LVEF >35% but ≤52% were more likely to receive benefit from physiologic pacing. Patients with chronic atrial fibrillation who underwent atrioventricular node ablation and pacemaker implant demonstrated clear improvement in LVEF with BiVP or HisBP versus RVP. CONCLUSION: Among patients with LVEF >35%, the LVEF remained preserved or increased with either BiVP or HisBP compared with RVP. However, patient-centered clinical outcome improvement appears to be limited primarily to patients who have chronic atrial fibrillation with rapid ventricular response rates and have undergone atrioventricular node ablation.