Chiari network for the interventional cardiologist: A hidden enemy at the heart gate - A systematic review of the literature.

BACKGROUND: This study aimed to collect and analyze the literature data regarding Chiari network (CN) and other right atrium (RA) remnants comprising the Eustachian and Thebesian valves (EV, ThV) as a potential entrapment site during different percutaneous cardiac procedures (PCP). METHODS AND RESULTS: A systematic search was conducted using Pubmed and Embase databases following the PRISMA guidelines to obtain available data concerning PCP associated with entrapment of inserted materials within CN-EV-ThV. The final analysis included 41 patients who underwent PCP with reported material entrapment within these RA remnants. The PCP was atrial septal defect (ASD)/patent foramen ovale (PFO) closure, catheter ablation, and pacemaker/defibrillator implantation in 44%, 22%, and 17% of patients, respectively. The entrapped materials were ASD/PFO devices, multipolar electrophysiology catheters, passive-fixation pacing leads, and J-guidewires in about 30%, 20%, 15%, and 10% of patients, respectively. Intraprocedural transthoracic, transoesophageal and intracardiac echocardiography showed sensitivity to reveal these structures of 20%, ∼95%, and 100%, respectively. A percutaneous approach successfully managed 70% of patients, while cardiovascular surgery was required in 20% and three patients died (7.3%). CONCLUSIONS: CN and other RA remnants may cause entrapment of various devices or catheters during PCP requiring right heart access. The percutaneous approach, guided by intraprocedural imaging, appears safe and effective in managing most patients. Prevention includes recognizing these anatomical structures at baseline cardiac imaging and intraprocedural precautions. Further studies are needed to analyze the actual incidence of this condition, its clinical impact and appropriate management.

Oral mexiletine for ventricular tachyarrhythmias treatment in implantable cardioverter-defibrillator patients: a systematic review of the literature.

INTRODUCTION: To evaluate the clinical outcomes of oral mexiletine (oMXT) to treat ventricular tachyarrhythmias (VTAs) in the era of implantable cardioverter-defibrillator (ICD) technology. EVIDENCE ACQUISITION: A systematic search was conducted using PubMed, Embase and Cochrane databases following the PRISMA guidelines to collect literature data reporting oMXT efficacy and safety outcomes in treating VTAs in ICD recipients. EVIDENCE SYNTHESIS: Final analysis included four studies accounting for a total of 91 patients with recurrent VTAs treated with oMXT. Amiodarone therapy was initially attempted in most patients (91.2%), while catheter ablation was performed in one-third of patients. VTA recurrences were observed in 55/91 patients (60.4%) during oMXT treatment compared to 91/91 (100%) before treatment (P<0.001). Appropriate therapies occurred in 55/88 ICD patients (62.5%) during oMXT treatment compared to 80/88 (90.9%) before treatment (P<0.001). After oMXT introduction, there was a significant reduction of the individual burden of VTA episodes and appropriate ICD therapies per patient, showing Hedges'g values of -1.103 (P=0.002) and -1.474 (P=0.008), respectively. Safety analysis showed a sample-weighted overall side-effect rate of 30%, while 21% of patients required drug reduction or discontinuation. Aggregated meta-regression analysis of the included studies and remote literature revealed a linear correlation between oMXT dosage and the overall side effects rate (r2 = 0.48; P=0.014). CONCLUSIONS: Oral mexiletine provides an adjunctive treatment to manage VTAs and reduces appropriate therapies in ICD patients with moderate efficacy and acceptable safety profiles. These observations await confirmation through randomised clinical trials.