Observational clinical and ex vivo studies have established a strong association between atrial fibrillation and inflammation1. However, whether inflammation is the cause or the consequence of atrial fibrillation and which specific inflammatory mediators may increase the atria's susceptibility to fibrillation remain elusive. Here we provide experimental and clinical evidence for the mechanistic involvement of myeloperoxidase (MPO), a heme enzyme abundantly expressed by neutrophils, in the pathophysiology of atrial fibrillation. MPO-deficient mice pretreated with angiotensin II (AngII) to provoke leukocyte activation showed lower atrial tissue abundance of the MPO product 3-chlorotyrosine, reduced activity of matrix metalloproteinases and blunted atrial fibrosis as compared to wild-type mice. Upon right atrial electrophysiological stimulation, MPO-deficient mice were protected from atrial fibrillation, which was reversed when MPO was restored. Humans with atrial fibrillation had higher plasma concentrations of MPO and a larger MPO burden in right atrial tissue as compared to individuals devoid of atrial fibrillation. In the atria, MPO colocalized with markedly increased formation of 3-chlorotyrosine. Our data demonstrate that MPO is a crucial prerequisite for structural remodeling of the myocardium, leading to an increased vulnerability to atrial fibrillation.

Background: Current surgical and medical treatment options for severe tricuspid regurgitation (TR) are limited, and additional interventional approaches are required. In the present observational study, the safety and feasibility of transcatheter repair of chronic severe TR with the MitraClip system were evaluated. In addition, the effects on clinical symptoms were assessed. Methods: Patients with heart failure symptoms and severe TR on optimal medical treatment were treated with the MitraClip system. Safety, defined as periprocedural adverse events such as death, myocardial infarction, stroke, or cardiac tamponade, and feasibility, defined as successful implantation of 1 or more MitraClip devices and reduction of TR by at least 1 grade, were evaluated before discharge and after 30 days. In addition, functional outcome, defined as changes in New York Heart Assocation class and 6-minute walking distance, were assessed. Results: We included 64 consecutive patients (mean age 76.6±10 years) deemed unsuitable for surgery who underwent MitraClip treatment for chronic, severe TR for compassionate use. Functional TR was present in 88%; in addition, 22 patients were also treated with the MitraClip system for mitral regurgitation as a combined procedure. The degree of TR was severe or massive in 88% of patients before the procedure. The MitraClip device was successfully implanted in the tricuspid valve in 97% of the cases. After the procedure, TR was reduced by at least 1 grade in 91% of the patients, thereof 4% that were reduced from massive to severe. In 13% of patients, TR remained severe after the procedure. Significant reductions in effective regurgitant orifice area (0.9±0.3cm 2 versus 0.4±0.2cm 2 ; P <0.001), vena contracta width (1.1±0.5 cm versus 0.6±0.3 cm; P =0.001), and regurgitant volume (57.2±12.8 mL/beat versus 30.8±6.9 mL/beat; P <0.001) were observed. No intraprocedural deaths, cardiac tamponade, emergency surgery, stroke, myocardial infarction, or major vascular complications occurred. Three (5%) in-hospital deaths occurred. New York Heart Association class was significantly improved ( P <0.001), and 6-minute walking distance increased significantly (165.9±102.5 m versus 193.5±115.9 m; P =0.007). Conclusions: Transcatheter treatment of TR with the MitraClip system seems to be safe and feasible in this cohort of preselected patients. Initial efficacy analysis showed encouraging reduction of TR, which may potentially result in improved clinical outcomes.

LVOT and LVOT calcium load, baseline right bundle branch block, and implantation depth were identified as independent predictors of the need for PPMI post-TAVR. Patient groups with different PPMI risk could be stratified using these 4 predictors. A slightly higher valve implantation site may prevent excessive PPMI rates.