Cardiac resynchronization therapy for pacing induced cardiomyopathy: Role of baseline right ventricular pacing burden.

BACKGROUND: Cardiac resynchronization therapy (CRT) is indicated for patients with heart failure with reduced left ventricular ejection fraction (LVEF) and chronic right ventricular (RV) pacing burden ≥40% (pacing-induced cardiomyopathy, PICM). It is uncertain whether baseline RV pacing burden impacts response to CRT. METHODS: We conducted a retrospective study of all CRT upgrades for PICM at our hospital from January 2017 to December 2018. Univariate and multivariable-adjusted changes in LVEF, and echocardiographic response (≥10% improvement in LVEF) at 3-12 months post-CRT upgrade were compared in those with RV pacing burden ≥90% versus <90%. RESULTS: We included 75 patients (age 74 ± 11 years, 71% male) who underwent CRT upgrade for PICM. The baseline RV pacing burden was ≥90% in 56 patients (median 99% [IQR 98%-99%]), and <90% in 19 patients (median 79% [IQR 73%-87%]). Improvement in LVEF was greater in those with baseline RV pacing burden ≥90% versus <90% (15.7 ± 9.3% vs. 7.5 ± 9.6%, p = .003). Baseline RV pacing burden ≥90% was a strong predictor of an improvement in LVEF ≥10% after CRT upgrade both in univariate and multivariate-adjusted models (p = .005 and .02, respectively). CONCLUSION: A higher baseline RV pacing burden predicts a greater improvement in LVEF after CRT upgrade for PICM.

Differences in outcomes among patients with atrial fibrillation undergoing catheter ablation with versus without intracardiac echocardiography.

BACKGROUND: Intracardiac echocardiography (ICE) use can lead to early detection of periprocedural complications and may improve patient outcomes by providing real-time visualization of catheter location and the treatment area during cardiac ablation (CA) for atrial fibrillation (AF). OBJECTIVE: Examine complications and 12-month healthcare use among patients with AF undergoing CA with versus without ICE use during the procedure in a real-world setting. METHODS: The 2015-2020 IBM MarketScan® Database was used to identify non-elderly adults (age 18-64 years) undergoing CA for AF. Patients were classified into ICE/non-ICE groups based on the presence or absence of ICE procedure codes. Patients in each group were matched on study covariates using propensity scores. Peri-procedural complications, 12-month cardiovascular (CV) or AF-related inpatient admission, repeat CA, and cardioversion were compared using a Cox proportional hazard model. RESULTS: 1371 patients were identified in each study cohort (ICE and non-ICE) after propensity matching. Patients who had CA with ICE had a significantly lower rate of complications than those without (2.9% vs. 5.8%; p < .001). The risk of complications was 50% lower with ICE use (hazard ratio [HR] 0.50; 95% confidence interval [CI] 0.34-0.72). For assessment of 12-month healthcare utilization, 1250 patients were identified in each cohort after propensity matching. ICE use was associated with a 36% lower risk of 12-month repeat ablation (HR 0.64; 95% CI 0.49-0.83). No differences in CV- or AF-related inpatient admission and cardioversion were observed. CONCLUSION: Among patients with AF, the use of ICE during an ablation procedure was associated with lower incidence of complications and repeat ablation.

Emerging Implantable-Device Technology for Patients at the Intersection of Electrophysiology and Heart Failure Interdisciplinary Care.

Cardiac implantable electronic devices, including implantable cardioverter-defibrillators and therapy, are part of guideline-indicated treatment for a subset of patients with heart failure with reduced ejection fraction. Current technological advancements in cardiac implantable electronic devices have allowed the detection of specific physiological parameters that are used to forecast clinical decompensation through algorithmic, multiparameter remote monitoring. Other recent emerging technologies, including cardiac contractility modulation and baroreflex activation therapy, may provide symptomatic or physiological benefits in patients without indications for cardiac resynchronization. Our goal in this state-of-the-art review is to describe the new commercially available technologies, their purported mechanisms of action, and the evidence surrounding their clinical roles, limitations and future directions. Finally, we underline the need for standardized workflow and close interdisciplinary management of this population to ensure the delivery of high-quality care.

Ventricular Arrhythmia in Cancer Patients: Mechanisms, Treatment Strategies and Future Avenues.

Cardiovascular disease and cancer are the leading causes of morbidity and mortality in the US. Despite the significant progress made in cancer treatment leading to improved prognosis and survival, ventricular arrhythmias (VA) remain a known cardiovascular complication either exacerbated or induced by the direct and indirect effects of both traditional and novel cancer treatments. Although interruption of cancer treatment because of VA is rarely required, knowledge surrounding this issue is essential for optimising the overall care of patients with cancer. The mechanisms of cancer-therapeutic-induced VA are poorly understood. This review will discuss the ventricular conduction (QRS) and repolarisation abnormalities (QTc prolongation), and VAs associated with cancer therapies, as well as existing strategies for the identification, prevention and management of cancer-treatment-induced VAs.

Autocrine regulation of myocyte Cx43 expression by VEGF.

Cardiac myocytes can rapidly adjust their expression of gap junction channel proteins in response to changes in load. Previously, we showed that after only 1 hour of linear pulsatile stretch (110% of resting cell length; 3 Hz), expression of connexin43 (Cx43) by cultured neonatal rat ventricular myocytes is increased by approximately 2-fold and impulse propagation is significantly more rapid. In the present study, we tested the hypothesis that vascular endothelial growth factor (VEGF), acting downstream of transforming growth factor-beta (TGF-beta), mediates stretch-induced upregulation of Cx43 expression by cardiac myocytes. Incubation of nonstretched cells with exogenous VEGF (100 ng/mL) or TGF-beta (10 ng/mL) for 1 hour increased Cx43 expression by approximately 1.8-fold, comparable to that observed in cells subjected to pulsatile stretch for 1 hour. Stretch-induced upregulation of Cx43 expression was blocked by either anti-VEGF antibody or anti-TGF-beta antibody. Stretch-induced enhancement of conduction was also blocked by anti-VEGF antibody. ELISA assay showed that VEGF was secreted into the culture medium during stretch. Furthermore, stretch-conditioned medium stimulated Cx43 expression in nonstretched cells. This effect was also blocked by anti-VEGF antibody. Upregulation of Cx43 expression stimulated by exogenous TGF-beta was blocked by anti-VEGF antibody, but VEGF-stimulation of Cx43 expression was not blocked by anti-TGF-beta antibody. Thus, stretch-induced upregulation of Cx43 expression is mediated, at least in part, by VEGF, which acts downstream of TGF-beta. Because the cultures contained only approximately 5% nonmyocytic cells, these results indicate that myocyte-derived VEGF, secreted in response to stretch, acts in an autocrine fashion to enhance intercellular coupling.

Lone atrial fibrillation: electrophysiology, risk factors, catheter ablation and other non-pharmacologic treatments.

Atrial fibrillation occurring in the absence of cardiovascular disease in individuals younger than 60 years is known as lone atrial fibrillation. Nearly 1-12% of atrial fibrillation is considered to be lone atrial fibrillation. As our understanding of atrial fibrillation grows, we wonder as to whether there is such as thing as "lone" atrial fibrillation? We know that male sex, obesity, obstructive sleep apnea, alcohol consumption and endurance sports increase the risk of developing lone atrial fibrillation. Family history of atrial fibrillation increases the risk strongly and there are several recognized mutations that are causative of lone atrial fibrillation. Common triggers for origin of atrial fibrillation are the pulmonary veins. The atrial substrate provides the reentry circuits for perpetuating the arrhythmia. The autonomic nervous system is a key modulator and allows the continuation of the atrial fibrillation. Catheter ablation has been very effective in the treatment of this condition. The ablation procedure involves isolation of the pulmonary veins, antrum, complex fractionated electrograms and other sites. Alternatively surgical techniques can be used to isolate the pulmonary veins and surgical techniques have evolved to minimally invasive procedures and these are as effective as catheter ablation. Early intervention improves the left atrial remodeling and may lead to fewer recurrences.