Background
The missing asymptomatic COVID‐19 infections have been overlooked because of the imperfect sensitivity of the nucleic acid testing (NAT). Globally understanding the humoral immunity in ...asymptomatic carriers will provide scientific knowledge for developing serological tests, improving early identification, and implementing more rational control strategies against the pandemic.
Measure
Utilizing both NAT and commercial kits for serum IgM and IgG antibodies, we extensively screened 11 766 epidemiologically suspected individuals on enrollment and 63 asymptomatic individuals were detected and recruited. Sixty‐three healthy individuals and 51 mild patients without any preexisting conditions were set as controls. Serum IgM and IgG profiles were further probed using a SARS‐CoV‐2 proteome microarray, and neutralizing antibody was detected by a pseudotyped virus neutralization assay system. The dynamics of antibodies were analyzed with exposure time or symptoms onset.
Results
A combination test of NAT and serological testing for IgM antibody discovered 55.5% of the total of 63 asymptomatic infections, which significantly raises the detection sensitivity when compared with the NAT alone (19%). Serum proteome microarray analysis demonstrated that asymptomatics mainly produced IgM and IgG antibodies against S1 and N proteins out of 20 proteins of SARS‐CoV‐2. Different from strong and persistent N‐specific antibodies, S1‐specific IgM responses, which evolved in asymptomatic individuals as early as the seventh day after exposure, peaked on days from 17 days to 25 days, and then disappeared in two months, might be used as an early diagnostic biomarker. 11.8% (6/51) mild patients and 38.1% (24/63) asymptomatic individuals did not produce neutralizing antibody. In particular, neutralizing antibody in asymptomatics gradually vanished in two months.
Conclusion
Our findings might have important implications for the definition of asymptomatic COVID‐19 infections, diagnosis, serological survey, public health, and immunization strategies.
The combination of NAT and serological testing for IgM antibody significantly improves the detection sensitivity of asymptomatic COVID‐19 infections, compared with NAT alone. S1‐specific IgM antibody response with rapid emergence and disappearance might be helpful to assist NAT for early identification of infectious individuals. A majority of asymptomatics induce very low levels of neutralizing antibody that disappear in two months. Abbreviations: NAT, nucleic acid testing; FI, fluorescence intensity; NT50, half‐maximal neutralizing titer.
Leadless pacing is a major breakthrough in the management of bradyarrhythmia. Results of initial clinical trials that have demonstrated a significant reduction in acute and long‐term pacing‐related ...complications have been confirmed by real‐world experience in a broader spectrum of patients. Nonetheless current use of a leadless pacemaker is hampered by its limited atrial sensing and pacing capability, as well as battery life‐span and retrievability. We review the current clinical outcome data, indications and contraindications, implantation and retrieval techniques, synchronous ventricular pacing, and other clinical considerations. We also provide an overview of the latest advancements in leadless pacing technology including device‐to‐device communication and energy harvesting technology.
The incidence of atrial tachycardia (AT) after rheumatic mitral valvular (RMV) surgery has been well described. However, there have been few reports on the characteristics, mechanism, and long-term ...ablation outcome of ATs after RMV surgery and concomitant Cox-MAZE IV procedure.The present study reviewed consecutive patients who underwent AT ablation between May 2008 and July 2013. All patients were refractory to antiarrhythmic drugs (AADs) and had a history of RMV surgery and Cox-MAZE IV procedure. A total of 34 patients underwent AT ablation after RMV surgery and concomitant Cox-MAZE IV procedure, and presented 57 mappable and 2 unmappable ATs. The 57 mappable ATs included 14 focal-ATs and 43 reentry-ATs. Ten of the 14 focal-like ATs were located at the pulmonary vein (PV) antrum and border of a box lesion. Of the 43 reentry-ATs, 16 were marco-reentrant around the mitral annulus (MA) and 16 around the tricuspid annulus. There were 41 atypical ATs (non-cavotricuspid isthmus related) including 16 ATs related to the box lesion and 21 ATs related to other Cox-MAZE IV lesions. The AT were successfully terminated in 33 (97.1%) patients. After mean follow-up of 46.9 ± 15.7 months, 25 (73.5%) patients maintained sinus rhythm without AADs after a single procedure and 28 (82.4%) patients after repeated procedures.The recurrent ATs after RMV surgery and concomitant Cox-MAZE IV were mainly reentry mechanism, and largely related to LA. An incomplete lesion or re-conductive gaps in a prior lesion might be the predominant mechanisms for these ATs. Catheter-based mapping and ablation of these ATs seems to be effective and safe during a long-term follow-up.
Highlights • The rates of new HF hospitalization among Chinese in Hong Kong between 2005 and 2012 were 0.59 per 1,000 population per year for males and 0.58 per 1,000 population per year for females. ...• In contrast to epidemiological studies from other Asian countries, the most prevalent comorbidities in our cohort were hypertension (69.8%) and coronary heart disease (29.3%). • The prognosis of new-onset HF was poor with high all-cause mortality and cardiovascular mortality for both HFpEF and HFrEF.
Heart failure (HF) increases the risk of thromboembolic events (TE). Study in a Caucasian population has shown that the CHA2DS2-VASc score predicts TE among HF patients without atrial fibrillation. ...We sought to assess the usefulness of the CHA2DS2-VASc score in predicting TE in an Asian population and refine the scoring system to improve its predictability of TE among HF patients in sinus rhythm.
A total of 1,202 consecutive patients who were admitted to our institution for new-onset HF from 2005 to 2012 and without atrial fibrillation or anticoagulation were retrospectively reviewed.
The mean age was 77.6 ± 12.2 years and 51.7% were female. After 36.2 ± 30.1 months, 113 (9.4%) developed TE. The annual incidence was 0.54%, 1.54%, 2.98% and 5.04% per year in those who had a CHA2DS2-VASc score of 1, 2-3, 4-5 and ≥6, respectively. In multivariate analysis, age ≥75 years Hazard ratio (HR) 2.59, 95% confidence interval (CI) 1.23-5.46, p = 0.012), chronic ischemic heart disease (HR 1.54, 95% CI 1.02-2.31, p = 0.040) and chronic kidney disease (HR 1.66, 95% CI 1.09-2.53, p = 0.018) independently predicted TE. Incorporation of chronic ischemic heart disease and chronic kidney disease into the CHA2DS2-VASc score significantly increased the area under the Receiver Operating Curve from 0.57 (95% CI 0.54-0.59) to 0.61 (95% CI 0.55-0.66; p = 0.022).
The CHA2DS2-VASc score is useful for stratification of the risk of TE among HF patients in sinus rhythm. Incorporation of chronic ischemic heart disease and chronic kidney disease into the score modestly improves its predictive value.
Si3N4 ceramic was densified at 1900°C for 12 hours under 1 MPa nitrogen pressure, using MgO and self‐synthesized Y2Si4N6C as sintering aids. The microstructures and thermal conductivity of ...as‐sintered bulk were systematically investigated, in comparison to the counterpart doped with Y2O3‐MgO additives. Y2Si4N6C addition induced a higher nitrogen/oxygen atomic ratio in the secondary phase by introducing nitrogen and promoting the elimination of SiO2, resulting in enlarged grains, reduced lattice oxygen content, increased Si3N4‐Si3N4 contiguity and more crystallized intergranular phase in the densified Si3N4 specimen. Consequently, the substitution of Y2O3 by Y2Si4N6C led to a great increase in ~30.4% in thermal conductivity from 92 to 120 W m−1 K−1 for Si3N4 ceramic.
Background
The use of high‐density electroanatomical mapping in the Chinese population for congenital heart disease (CHD) is not well reported.
Methods
Retrospective review of consecutive ...transcatheter ablation of atrial tachyarrhythmia using high‐density mapping for CHD patients (at least moderate complexity) in the only tertiary congenital heart center in the territory from January 2017 to January 2019 was conducted. Orion mapping catheter in Rhythmia system (Boston Scientific) was used to create activation and voltage maps. Parameters including mechanism of arrhythmia, acute success, and follow‐up data were recorded.
Results
Eight patients were identified (median age 35.5 years) who underwent transcatheter ablation of atrial arrhythmia. More than one reentry circuits of IART were identified in five patients. It took a median of 32.4 minutes with 15,952 (IQR 13,395‐18,530) mapping points per map. Cavo‐annulus isthmus‐dependent mechanism was the predominant reentry mechanism. Acute success with the elimination of all inducible tachycardia was achieved in six patients (75%), and partial success in two patients. There was recurrence of atrial arrhythmia in four patients (50%), in which three patients could be maintained in sinus rhythm with low‐dose antiarrhythmic medication. Targeted substrate ablation was performed in six patients with multiple IART circuits. Critical anatomical pouches were identified in three patients, which were missed in the initial mapping using Orion basket mapping catheter.
Conclusions
High acute success rate of atrial arrhythmia ablation can be achieved using high‐density anatomical mapping in CHD. Substrate ablation was required with multiple IART circuits identified. Vigilance should be sought to identify anatomical pouches.
High acute success rate of atrial arrhythmia ablation can be achieved using high‐density anatomical mapping in CHD. Vigilance should be sought to identify anatomical pouches.
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