Radiation therapy in patients with cardiac implantable electronic devices.

BACKGROUND: The number of patients with cardiac implantable electronic devices (CIEDs) treated with radiation therapy (RT) as an oncological treatment is expected to increase. AIMS: The aim of the study was to assess whether cancer treatment with radiation therapy is associated with any device dysfunctions and device­related threats in patients with CIEDs. METHODS: The risk of all patients with CIEDs undergoing RT was assessed according to guidelines. Device interrogations were performed before the first and after the last RT session. In patients at high risk and/or with an implantable cardioverter­defibrillator or cardiac resynchronization therapy with defibrillator (CRT­D), all sessions were supervised by a cardiologist, and device interrogations were performed before and after every single RT session. Device parameters and events were monitored during thewhole treatment. RESULTS: The study included 157 patients with CIEDs who had palliative (n = 71) or radical (n = 86) RT. Pacemakers were implanted in 113 patients, implantable cardioverter­defibrillators in 36, and CRT­D in 8. During the 2396 RT sessions (median [interquartile range], 5 [5-28] per patient) with cumulative dose up to 78 Gy per patient for the whole RT treatment and maximum energy beam up to 20 MV, 2 events potentially related to radiation were recorded. CONCLUSIONS: Radiation therapy in patients with CIEDs is not associated with substantial risk to the patients assuming the patients' management follows current guidelines.

Bipolar ablation with contact force-sensing of swine ventricles shows improved acute lesion features compared to sequential unipolar ablation.

INTRODUCTION: Despite technical progress, ventricular tachycardia (VT) recurrence after unipolar ablation remains relatively high (12%-47%). Bipolar ablation has been proposed as an appealing solution that may overcome limitations associated with unipolar ablation settings. We designed an animal study to compare bipolar (BPA) vs sequential unipolar ablation (UPA) using contact force-sensing technology on both ablation catheters. METHODS: Twenty large white female pigs (6-months-old, 50-60 kg) underwent multiple RF ablations (30 W, 60 seconds, 30 mL/min irrigation) on the ventricular myocardium from the epicardial and endocardial sides. The hearts were fixed and scanned with high-resolution cardiac magnetic resonance imaging. Thermal lesions were located and characterized in volume, depth, width, and transmurality. RESULTS: Lesion volume was calculated as the sum of epicardial or endocardial conjoined/isolated lesions at one location. Linear dimensions (width and depth) were measured twice for each location, on the endocardial and epicardial side. We evaluated 35 lesions across the intraventricular septum (UPA, N = 17 vs BPA, N = 18). No difference in volume, linear dimensions or impedance drop was observed in this area between UPA and BPA. However, BPA required half RF time and showed an increased transmurality trend. We then analyzed 73 lesions from the endocardial side (UPA, N = 35 vs BPA, N = 38) and 50 from the epicardial side (UPA, N = 11 vs BPA N = 39) of the ventricular free walls. Lesion transmurality was markedly improved by BPA (P = .030, odds ratio, 23.73 [4.71,31.96]). Ventricular BPA lesions were significantly deeper on the epicardial side (P < .0001) and endocardial side (P = .015). CONCLUSION: Bipolar ablation is more likely to create transmural and epicardial lesions in the ventricle wall. Half the time is needed for the creation of comparably deep and large lesions.

Comparing the incidence of ventricular arrhythmias during epicardial ablation in swine versus canine models.

BACKGROUND: Choosing the appropriate animal model for development of novel technologies requires an understanding of anatomy and physiology of these different models. There are little data about the characteristics of different animal models for the study of technologies used for epicardial ablation. We aimed to compare the incidence of ventricular arrhythmias during epicardial radiofrequency ablation between swine and canine models using novel epicardial ablation catheters. METHODS: We conducted a retrospective study using data obtained from epicardial ablation experiments performed on swine (Sus Scrofa) and canine (Canis familiaris) models. We compared the incidence of ventricular arrhythmias during ablation between swine and canine using multivariate regression analysis. Six swine and six canine animals underwent successful epicardial radiofrequency ablation. A total of 103 ablation applications were recorded. RESULTS: Ventricular arrhythmias requiring cardioversion occurred in 13.11% of radiofrequency ablation applications in swine and 9.75% in canine (relative risk: 117.6%, 95% confidence interval [CI]: 83.97-164.69, animal-based odds ratio [OR]: .55, 95% CI: .23-61.33; P = .184). When adjusting for application position, duration of ablation and power, the odds of developing potentially lethal ventricular arrhythmia in swine increased significantly compared to canine (OR: 3.60, 95% CI: 1.35-9.55; P = .010). CONCLUSIONS: The swine myocardium is more susceptible to developing ventricular arrhythmias compared to canine model during epicardial ablation. This issue should be carefully considered in future studies.

Irreversible electroporation ablation for atrial fibrillation.

Atrial fibrillation (AF) is one of the most important problems in modern cardiology. Thermal ablation therapies, especially radiofrequency ablation (RF), are currently "gold standard" to treat symptomatic AF by localized tissue necrosis. Despite the improvements in reestablishing sinus rhythm using available methods, both success rate and safety are limited by the thermal nature of procedures. Thus, while keeping the technique in clinical practice, safer and more versatile methods of removing abnormal tissue are being investigated. This review focuses on irreversible electroporation (IRE), a nonthermal ablation method, which is based on the unrecoverable permeabilization of cell membranes caused by short pulses of high voltage/current. While still in its preclinical steps for what concerns interventional cardiac electrophysiology, multiple studies have shown the efficacy of this method on animal models. The observed remodeling process shows this technique as tissue specific, triggering apoptosis rather than necrosis, and safer for the structures adjacent the myocardium. So far, proposed IRE methodologies are heterogeneous. The number of devices (both generators and applicators), techniques, and therapeutic goals impair the comparability of performed studies. More questions regarding systemic safety and optimal processes for AF treatment remain to be answered. This work provides an overview of the electroporation process, and presents different results obtained by cardiology-oriented research groups that employ IRE ablation, with focus of AF-related targets. This contribution on the topic aspires to be a practical guide to approach IRE ablation for cardiac arrhythmias, and to highlight controversial features and existing knowledge, to provide background for future improved experimentation with IRE in arrhythmology.

The influence of ablation power reduction associated with oesophagus location on pulmonary vein isolation results in patients with paroxysmal atrial fibrillation: six-month follow-up.

BACKGROUND: Catheter ablation of atrial fibrillation (AF) could be associated with a thermal oesophageal (EO) injury. To avoid this complication intraluminal EO temperature monitoring and ablation power reduction at the areas with excessive heating could be used. However, the reduced energy could limit the ablation lesion depth, without creation of lasting transmural scar and influence on long-term ablation results. AIM: The primary goal was to evaluate the homogeneity of forced ablation power reduction due to excessive EO heating in different parts of the left atrium. The secondary goal was to assess the influence of power reduction in different EO locations on long-term AF recurrence. METHODS: We examined retrospectively 109 consecutive patients with symptomatic, medically refractory paroxysmal AF, who underwent pulmonary vein isolation using radiofrequency ablation. In 40.4% of the patients the EO course was central (group B) left atrium posterior wall, in 31.2% it was left sided (group A), and in 28.4% it was right sided (group C). RESULTS: The maximal measured temperature (41.0 ± 1.0 vs. 39.2 ± 1.5 vs. 40.6 ± 0.7°C) and forced ablation power (15.9 ± 5.6 vs. 23.5 ± 6.1 vs. 17.4 ± 5.7 W) differed significantly according to the EO course (A, B, C, respectively). In six-month follow-up 76.15% of patients were free of arrhythmias. There was no statistically significant difference between groups (A-C) regarding the AF recurrence rate: 32.4% vs. 20.5% vs. 19.4% (p = 0.37). CONCLUSIONS: The maximal intraluminal EO temperatures and the necessary level of power reduction during AF ablation are inhomogeneous in different parts of the left atrium, but they are not associated with different six-month follow-up results.

Evaluation of safety and efficacy of NexGen - an ultrathin strut and hybrid cell design cobalt-chromium bare metal stent implanted in a real life patient population - the Polish NexGen Registry.

INTRODUCTION: Despite the dominance of drug-eluting stents in modern interventional cardiology, there is still a niche for bare metal stents. AIM: The aim of the Polish NexGen registry was to evaluate the safety and efficacy of a new generation cobalt-chromium NexGen stent in a real life patient population. MATERIAL AND METHODS: A prospective multi-center registry was conducted in five clinical sites of American Heart of Poland. Three hundred and eighty-three patients who underwent percutaneous coronary intervention (PCI) with NexGen stent implantation were included. Clinical follow-up was performed at 1, 6 and 12 months. Additionally, a group of 42 randomly selected patients underwent control angiography at 6 months (10.96% of study population). The primary endpoint was occurrence of target vessel revascularization (TVR) at 6-month follow-up. Angiographic endpoints included rates of binary restenosis and late lumen loss at 6-month follow-up based on QCA analysis. Multivessel disease was present in more than 70% of patients, and 52.4% of lesions were complex. The main indications for angiography were non-ST elevation acute coronary syndromes (54.8%) and ST elevation myocardial infarction (34.99%). RESULTS: At 6-month follow-up 47 (12.7%) patients reached the primary endpoint of TVR. The composite of major acute cardiac event rates at 30-day and 6- and 12-month follow-up was 6.01% (n = 23), 18.5% (n = 69) and 25.21% (n = 92) respectively. Control angiography performed after 6 months showed in-stent late loss of 0.66 ±0.71 mm and a binary restenosis rate of 16.7%. CONCLUSIONS: Our study showed that PCI with the NexGen stent is safe and effective at 6- and 12-month follow-up. Angiographic results showed a satisfactory restenosis rate and low late lumen loss.