Background: The improve sudden cardiac arrest (SCA) study was a nonrandomized prospective global study that identified a subset of primary prevention (PP) patients at an elevated risk for SCA labeled 1.5PP. These 1.5PP patients had one or more of the following additional risk factors: Syncope, nonsustained ventricular tachycardia, premature ventricular contractions >10/h, and left ventricular ejection fraction <25%. The purpose of this sub-analysis was to examine the China population cohort according to the improve SCA study's primary and secondary objectives. We aim to analyze the improve SCA study objective outcomes explicitly in the Chinese cohort to better understand the utility of PP implantable cardioverter-defibrillator (ICD) therapy in China. Subjects and Methods: The improve SCA study enrolled patients (n = 4222) during March 2014 and July 2017, including 87 sites in 17 countries from the geographies of Asia, Latin America, Eastern Europe, the Middle East, and Africa. In this analysis, the China cohort of improve SCA patients (n = 1654) was analyzed according to the objectives of the main study; the primary objective compared time to first appropriate ventricular tachycardia (VT) or ventricular fibrillation (VF) therapy between 1.5PP (n = 904) and secondary prevention (SP) patients (n = 470). All-cause mortality rates of 1.5PP with ICDs versus no implant, and an analysis of ischemic versus nonischemic results (n = 280) were also analyzed. PP patients without an additional risk factor were labeled 1.0PP (n = 280). Cox-proportional hazards model was used for hazard ratio (HR) calculations. This study was approved by the Ethics Committee of each participating institution and the associated national and local regulatory agencies, and registered with ClinicalTrials.gov (identifier: NCT02099721). Results: The time to first VT/VF therapy for 1.5PP was not within 30% of SP (HR = 0.42, 95% confidence interval [CI]: 0.31–0.56, P < 0.0001). However, there was a 49% reduction (HR = 0.51, 95% CI: 0.35–0.74, P = 0.0004) in all-cause mortality in the 1.5PP implanted versus nonimplanted patients, and a 70% reduction (HR = 0.30, 95% CI: 0.09–0.99, P = 0.05) in 1.0PP implanted patients. Nonischemic cardiomyopathy (NICM) 1.5PP patients showed a 51% reduction (HR = 0.49, 95% CI: 0.34–0.77, P = 0.0012) in all-cause mortality compared to those who did not receive an ICD implant. Conclusion: The China populations of 1.0PP and 1.5PP patients obtain a significant benefit with implantable defibrillation therapy.

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We report a 61-year-old male who presented with recurrent syncopal episodes following 1 week of headaches, fevers, and malaise. Initial evaluation suggested sinus node dysfunction with a primary cardiac etiology; however, he was ultimately diagnosed with herpes simplex virus (HSV) encephalitis after suggestive findings on brain imaging and confirmation by positive HSV polymerase chain reaction in cerebrospinal fluid. The patient was treated medically and recovered without further intervention. Sinus arrest due to HSV encephalitis is a rare phenomenon that has been described infrequently in the literature. This case report highlights the importance of recognizing reversible causes of sinus node dysfunction to avoid unnecessary permanent pacemaker implantation. This study was approved by the Institutional Review Board of UnityPoint Health-Des Moines, USA (approval No. EX2020-014) on March 8, 2020.

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Background: In recent years, catheter ablation has been widely used in the treatment of paroxysmal atrial fibrillation (AF). Radiofrequency ablation has long been standard of care, whereas cryoballoon ablation has emerged as a new alternative for the treatment of paroxysmal AF. The present study aims to investigate the efficacy and safety of radiofrequency ablation and cryoballoon ablation for paroxysmal AF. Subjects and Methods: This retrospective nonrandomized controlled study consecutively enrolled 582 patients with paroxysmal AF who underwent radiofrequency ablation or cryoballoon ablation for the first time in Nanjing Drum Tower Hospital from September 2014 to October 2018. The enrolled patients were divided into four groups according to the ablation energy source used and instruments: normal saline irrigation catheter group (Group A), contact force-sensing catheter group (Group B), first-generation cryoballoon group (Group C), and second-generation cryoballoon group (Group D). The procedure time, X-ray exposure time, procedural complications, and 1-year recurrence rate were observed. This study was approved by the Medical Ethics Committee of Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, China (approval No. 2014-190-01) on August 6, 2014. Results: There were no significant differences in baseline patient characteristics among the four groups. There were significant differences in the procedure times among Groups A, B, C, and D (163.6 ± 49.3, 142.4 ± 40.5, 136.6 ± 30.4, and 114.6 ± 24.2 min, respectively; P < 0.01). Moreover, the significant difference also existed in the X-ray exposure times among Groups A, B, C, and D (22.2 ± 8.4, 13.6 ± 8.7, 31.5 ± 7.3, and 26.5 ± 8.5 min, respectively; P < 0.01). In terms of procedural complications, the incidence of phrenic nerve palsy in patients who underwent cryoballoon ablation in Groups C and D was significantly higher than that under radiofrequency ablation in Groups A and B (P < 0.05), and there were no significant differences in the incidence of other procedural complications. The 1-year recurrence rates of AF/atrial flutter/atrial tachycardia in Groups A, B, C, and D were 23.8%, 15.4%, 15.1%, and 11.6%, respectively. Among them, the recurrence rates in Groups B and D were significantly lower than that in Group A (P < 0.05). Conclusions: The efficacy of a contact force-sensing catheter or second-generation cryoballoon in the treatment of paroxysmal AF is better than that of normal saline irrigation catheter. Both radiofrequency ablation and cryoballoon ablation are safe, and phrenic nerve palsy is a complication that requires special attention for cryoballoon ablation.

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