EHRA White Paper: knowledge gaps in arrhythmia management—status 2019

Clinicians accept that there are many unknowns when we make diagnostic and therapeutic decisions. Acceptance of uncertainty is essential for the pursuit of the profession: bedside decisions must often be made on the basis of incomplete evidence. Over the years, physicians sometimes even do not realize anymore which the fundamental gaps in our knowledge are. As clinical scientists, however, we have to halt and consider what we do not know yet, and how we can move forward addressing those unknowns. The European Heart Rhythm Association (EHRA) believes that scanning the field of arrhythmia / cardiac electrophysiology to identify knowledge gaps which are not yet the subject of organized research, should be undertaken on a regular basis. Such a review (White Paper) should concentrate on research which is feasible, realistic, and clinically relevant, and should not deal with futuristic aspirations. It fits with the EHRA mission that these White Papers should be shared on a global basis in order to foster collaborative and needed research which will ultimately lead to better care for our patients. The present EHRA White Paper summarizes knowledge gaps in the management of atrial fibrillation, ventricular tachycardia/sudden death and heart failure.

Incidence of thromboembolic events following atrial fibrillation catheter ablation and rate control strategies according to the kind of oral anticoagulation: A systematic review and meta-analysis

INTRODUCTION

Anticoagulantion therapy (OAT) represents the cornerstone to reduce thromboembolic events for atrial fibrillation (AF). Recent studies suggest that AF catheter ablation on top of OAT may be useful to further reduce the thromboembolic risk in AF patients. The aim of the present study is to compare the long-term risk of thromboembolic events and treatment-related complications in patients with AF treated by OAT strategies and catheter ablation.

METHODS

Pubmed, Cochrane and Google Scholar were searched for studies including >500 patients evaluating AF patients treated with OAT (VKA: vitamin K antagonist or DOAC: Direct oral anticoagulants) and/or AF ablation. Pooled incidence of stroke/year was the primary end point, while that of stroke, of all cause bleeding and of major bleeding the secondary ones. All the analyses were stratified according to the CHADS₂ score of included patients.

RESULTS

Overall, 27 studies were selected, including 50,973 patients in the AF catheter ablation group; 281,595 patients in the VKA group; 54,811 patients in the DOAC group. After a mean follow-up of 2.4 (1.5-3.8) years, the overall incidence of stroke and thromboembolic events was 0.63 per 100 patients/year in AF ablation group, 2.09 per 100 patients/year in VKA group and 1.24 per 100 patients/year in DOAC group (p < 0.001). After stratification in 4 groups according to CHADS₂ score, the incidence of thromboembolic events remained lower in patients included in the AF ablation, followed by DOAC and VKA respectively (p < 0.001), for each CHADS₂ cluster. Both the incidence of all cause bleedings and major bleedings resulted lower in AF ablation group (p < 0.001). The incidence of all-cause mortality in the AF ablation group was significant lower than in the group of OAT (p < 0.0001).

CONCLUSION

AF catheter ablation significantly reduces the incidence of long-term thromboembolic events compared to both VKA and DOAC. This reduction is maintained in all CHADS₂ score clusters and is strengthened by the concomitant reduction in hemorrhagic complications provided by AF ablation.

Feasibility of in vivo transesophageal cardiac ablation using a phased ultrasound array

Over 2.2 million Americans suffer from atrial fibrillation making it one of the most common arrhythmias. Cardiac ablation has shown a high rate of success in treating paroxysmal atrial fibrillation. Prevailing modalities for this treatment are catheter based radio-frequency ablation or surgery. However, there is measurable morbidity and significant costs and time associated with these invasive procedures. Due to these issues, developing a method that is less invasive to treat atrial fibrillation is needed. In the development of such a device, a transesophageal ultrasound applicator for cardiac ablation was designed, constructed and evaluated. A goal of this research was to create lesions in myocardial tissue using a phased array. Based on multiple factors from array simulations, transesophageal imaging devices and throat anatomy, a phased ultrasound transducer that can be inserted into the esophagus was designed and tested. In this research, a two-dimensional sparse phased array with the aperture size of 20.7 mm x 10.2 mm with flat tapered elements as a transesophageal ultrasound applicator was fabricated and evaluated with in vivo experiments. Five pigs were anesthetized; the array was passed through the esophagus and positioned over the heart. The array was operated for 8-15 min at 1.6 MHz with the acoustic intensity of 150-300 W/cm(2) resulting in both single and multiple lesions on atrial and ventricular myocardium. The average size of lesions was 5.1 +/- 2.1 mm in diameter and 7.8 +/- 2.5 mm in length. Based on the experimental results, the array delivered sufficient power to the focal point to produce ablation while not grossly damaging nearby tissue outside the target area. These results demonstrate a potential application of the ultrasound applicator to transesophageal cardiac surgery in atrial fibrillation treatment.