Improvement in renal function following cryoballoon ablation for atrial fibrillation

Purpose

Patients with chronic kidney disease are predisposed to heart rhythm disorders including atrial fibrillation (AF). Several studies have suggested that radiofrequency catheter ablation of AF improves renal function. However, little data exists for pulmonary vein isolation with cryoballoon ablation (CBA). The purpose of this study is to assess change in renal function following CBA for AF.

Method

This is a single-center retrospective study that included patients who underwent CBA for AF between 2011 and 2016. Patients were grouped by baseline-estimated glomerular filtration rate (eGFR): ≥?90 (Stage G1), 60–89.9 (Stage G2), and 30–59.9 mL/min/1.73 m² (Stage G3). Change in eGFR was assessed >?3 months post-ablation.

Results

A total of 306 patients with both pre- and post-ablation serum creatinine measurements available were included. Baseline eGFRs for Stages G1, G2, and G3 patients were 103.5?±?12.9 (n?=?82), 74.7?±?8.2 (n?=?184), and 52.6?±?6.6 mL/min/1.73 m² (n?=?40), respectively. Renal function was assessed 310.8?±?104.2 days post-ablation. Average intra-procedural contrast use was 58.4?±?23.8 mL. There was no significant change in eGFR following CBA in Stage G1 patients (p?=?0.10). For those with Stages G2 and G3 renal function, eGFR improved by 6.1% (4.2 mL/min/1.73 m², p?<?0.01) and 13.8% (7.2 mL/min/1.73 m², p?<?0.01), respectively. This improvement was seen regardless of the presence or absence of recurrent atrial arrhythmias.

Conclusions

CBA for AF may be associated with an improvement in renal function, particularly among those with a reduced baseline eGFR despite recurrence of atrial arrhythmias and intra-procedural contrast use.

     

Comparison of the predictive value of exercise-induced ST depression versus exercise technetium-99m sestamibi single-photon emission computed tomographic imaging for detection of coronary artery disease in patients with left ventricular hypertrophy

Scant knowledge exists regarding the significance of either additional ST depression in the presence of baseline depression or new stress-induced ST depression in patients with left ventricular (LV) hypertrophy. Accordingly, the purpose of this investigation is to determine whether the appearance and/or severity of ST abnormalities during exercise stress testing can accurately predict the prevalence of ischemic burden as measured by quantitative technetium-99m-sestamibi single-photon emission computed tomographic imaging in patients with LV hypertrophy. The results show that the presence of exercise ST-segment depression, as well as its magnitude, are not accurate predictors for identifying patients with coronary artery disease in the presence of electrocardiographic criteria for LV hypertrophy.     

Atrial fibrillation and atrial cardiomyopathies

Atrial fibrillation (AF) is the most common arrhythmia among adults. While there have been incredible advances in the management of AF and its clinical sequelae, investigation of atrial cardiomyopathies (ACMs) is becoming increasingly more prominent. ACM refers to the electromechanical changes—appreciated subclinically and/or clinically—that underlie atrial dysfunction and create an environment ripe for the development of clinically apparent AF. There are several subtypes of ACM, distinguished by histologic features. Recent progress in cardiovascular imaging, including echocardiography with speckle-tracking (e.g., strain analysis), cardiovascular magnetic resonance imaging (CMR), and atrial 4-D flow CMR, has enabled increased recognition of ACM. Identification of ACM and its features carry clinical implications, including elevating a patient's risk for development of AF, as well as associations with outcomes related to catheter-based and surgical AF ablation. In this review, we explore the definition and classifications of ACM, its complex relationship with clinical AF, imaging modalities, and clinical implications. We propose next steps for a more unified approach to ACM recognition that can direct further research into this complex field.     

Potent antigen-specific immune responses stimulated by codelivery of CpG ODN and antigens in degradable microparticles

CpG ODN stimulates a TH1 response through its receptor Toll-like receptor 9 (TLR9). TLR9 is a receptor that is found intracellularly. Microparticles are efficiently internalized by dendritic cells (DCs) and macrophages and would thus be an ideal delivery vehicle for CpG ODN to reach its target site thereby enhancing the TH1 response to an antigen also encapsulated in the microparticle. Here, we show that careful control over fabrication parameters can produce biodegradable microparticles with predictable size distributions, surface morphology, and shape. Entrapment efficiencies of the model antigen OVA ranged from 19% to 23% with an average loading of 10 microg/mg of microparticles. For CpG ODN, these values were 33% to 35%, which corresponded to an average loading of 8.5 microg/mg of microparticles. The microparticles release CpG ODN and OVA in a burst followed by sustained release profile. At the highest concentration of microparticles incubated with a pure DC cell line, 92% of DCs had internalized microparticles by 16 hours, confirming that DCs efficiently take up the microparticles. Microparticles are capable of inducing DC maturation as determined by up-regulation of CD80 and CD86 markers. Although the presence of CpG ODN in the microparticles did not impact on the phenotype of the DCs, it was necessary for DCs to induce activation of antigen-specific T cells as indicated by interferon-gamma production. Microparticles entrapping both antigen and CpG ODN induced significantly higher amounts of anti-OVA antibody production than other preparations such as the soluble OVA and CpG ODN (P<0.01) and stimulated stronger IgG2a production than delivery of microparticles entrapping antigen alone. We conclude that co-encapsulating immunostimulatory CpG ODN and antigen in degradable microparticles is an effective approach to enhancing development of a TH1 immune response.     

Recovery of pacemakers and defibrillators for analysis and device advance directives: electrophysiologists' perspectives

Background: Following high‐profile device failures, the Heart Rhythm Society emphasized the need for postmarketing surveillance by recommending that physicians return all explanted devices to the manufacturer for analysis. Methods: We conducted a national survey of electrophysiologists (EPs) regarding recovery for analysis of explanted pacemakers and implantable cardioverter defibrillators (devices), and attitudes toward device‐specific advance directives to facilitate return of devices. Online survey invitations were sent in four waves from December 2008 to June 2009 to 300 e‐mail addresses from the Heart Rhythm Society member database. Results: From 250 invitations, there were 95 responses (38%). Demographics included average age 50 years (range, 31–87); 95% male; 81% Caucasian. Only 23% reported returning all explanted devices to the manufacturers. Of all the respondents, 32% discarded >10 devices/year as medical waste, 42% stored devices in a box in the electrophysiology lab, and 10% donated at least 1 device/year to charity for reuse overseas. Sixty‐seven percent felt that it would not be helpful to have an advance directive specifying what the patient would want done with their device postmortem. Conclusions: Few EPs return all explanted devices or send interrogation reports to the manufacturers, though nearly all said it was easy to do so. A majority either dispose of explanted devices as medical waste or store them in laboratories or offices, and a small percentage donate for reuse in underserved nations or to veterinary hospitals. This study suggests a need for initiatives such as educational campaigns to increase the retrieval and return of devices, either for analysis or reuse. (PACE 2011; 659–665)     

Prevalence and predictors of complications of radiofrequency catheter ablation for atrial fibrillation

Complications of Atrial Fibrillation Ablation. Introduction: Up to 6% of patients experience complications after radiofrequency catheter ablation (RFA) of atrial fibrillation (AF). The purpose of this study is to determine the prevalence and predictors of periprocedural complications after RFA for AF. Methods and Results: The subjects were 1,295 consecutive patients (age = 60 ± 10 years) who underwent RFA (n = 1,642) for paroxysmal (53%) or persistent AF (47%) from January 2007 to January 2010. A complication occurred in 57 patients (3.5%); a vascular access complication in 31 (1.9%); pericardial tamponade in 20 (1.2%); a thromboembolic event in 4 (0.2%); deep venous thrombosis in 1 (<0.01%); and pulmonary vein stenosis in 1 patient (<0.01%). There were no procedure‐related deaths. On multivariate analysis, female gender (OR = 2.27; ±95% CI: 1.31–2.57, P < 0.01) and procedures performed in July or August (OR = 2.10; ±95% CI: 1.16–3.80, P = 0.01) were independent predictors of any complication. For vascular complications, treatment with clopidogrel (OR = 4.40; ±95% CI: 1.43–13.53, P = 0.01), female gender (OR = 3.65; ±95% CI: 1.72–7.75, P < 0.01) and performing RFA in July or August (OR = 2.71; ±95% CI: 1.25–5.87, P = 0.01) were independent predictors. The only predictor of cardiac tamponade was prior RFA (OR = 3.32; ±95% CI: 0.95–11.61; P < 0.05). Conclusion: Prevalence of perioperative complications for RFA of AF is 3.5% and vascular access complications constitute the majority. The need for clopidogrel therapy should be carefully considered prior to RFA. At teaching institutions close supervision should be exercised during vascular access early in the year. Improvements in ablation technology and elimination of the need for repeat procedures may decrease the risk of pericardial tamponade . (J Cardiovasc Electrophysiol, Vol. 22, pp. 626‐631, June 2011)