Predictors of increase in pacing threshold after transcatheter pacing system implantation due to micro-dislodgement.

BACKGROUND: Achieving a favorable pacing threshold with a Micra transcatheter pacing system (Micra-TPS) is needed to reduce battery depletion. In some cases, the threshold increases shortly after the device is implanted, and a higher pacing threshold may be required. This study aims to identify the causes and predictors of the increase in pacing threshold observed shortly after Micra-TPS implantation. METHODS: The study included 64 consecutive patients who underwent Micra-TPS implantation between 2017 and 2020. The patients were divided into two groups depending on their pacing threshold: the increased pacing threshold (IPT) group (threshold increased by ≥0.5 V/0.24 ms within 1 month of implantation) and the stable pacing threshold (SPT) group. RESULTS: Excluding four patients who could not be followed up, of the 60 remaining patients, nine (15%) were in the IPT group and 51 (85%) were in the SPT group. The IPT group had significantly lower implant impedance values and higher implant thresholds than the SPT group (582 ± 59 vs 755 ± 167 Ω [P < .001] and 1.29 ± 0.87 vs 0.71 ± 0.40 V/0.24 ms [P = .014]). Implant impedance and threshold may serve as predictors of a threshold increase after implantation (area under the curve: 0.737-0.943 and 0.586-0.926, respectively). CONCLUSIONS: An IPT was noted shortly after Micra-TPS implantation owing to micro-dislodgement because of insufficient anchoring of the device to the myocardium. Impedance >660 Ω and threshold <1.0 V/0.24 ms may predict an increase in pacing threshold.

Clinical Courses of Two Pediatric Patients with Acute Megakaryoblastic Leukemia Harboring the CBFA2T3-GLIS2 Fusion Gene.

Acute megakaryoblastic leukemia (AMKL) in children without Down syndrome (DS) has an extremely poor outcome with 3-year survival of less than 40%, whereas AMKL in children with DS has an excellent survival rate. Recently, a novel recurrent translocation involving CBFA2T3 and GLIS2 was identified in about 30% of children with non-DS AMKL, and the fusion gene was reported as a strong poor prognostic factor in pediatric AMKL. We report the difficult clinical courses of pediatric patients with AMKL harboring the CBFA2T3-GLIS2 fusion gene.

Gender differences in the association between serum uric acid and prognosis in patients with acute coronary syndrome.

BACKGROUND: Increased levels of uric acid (UA) have been associated with cardiovascular disease. This association is generally stronger in women than men. However, gender differences in the prognostic value of UA in patients with acute coronary syndrome (ACS) are unknown. We investigated gender differences in the relationship between UA level and the prognosis in patients with ACS. METHOD: This was an observational analysis of patients with ACS undergoing percutaneous coronary intervention enrolled in the Ibaraki Cardiac Assessment Study (ICAS) registry. We analyzed 1380 patients (330 women, 1050 men) with ACS who had information on UA. We assessed the association between UA and the incidence of major cardiovascular adverse events (MACE), defined as all-cause death, congestive heart failure, reinfarction, and stroke. Patients were divided according to gender-specific UA quartile. RESULTS: The mean UA level in women was significantly lower than that in men (4.9mg/dl vs 5.9mg/dl, p<0.001). After a median duration of follow-up period of 437 days (interquartile range 222-801 days), MACE had occurred in 186 (13%) patients [56 (17%) events in women; 130 (12%) events in men]. Kaplan-Meier analysis for MACE-free survival demonstrated that a higher quartile of UA was associated with MACE in both women and men (p<0.001, p=0.002, respectively). Multivariate Cox regression analysis revealed that the highest quartile of UA, as compared with the lowest quartile of UA, was an independent predictor of MACE in women [hazard ratio (HR), 2.84; 95% CI, 1.19-6.77; p=0.018] but not in men (HR, 1.32; 95% CI, 0.66-2.64; p=0.422). CONCLUSIONS: An increased level of UA was associated with MACE more strongly in women than in men with ACS. These results suggest that there are gender differences in the association of UA level with the prognosis in patients with ACS.

Difference in the Clinical Characteristics of Ventricular Fibrillation Occurrence in the Early Phase of an Acute Myocardial Infarction Between Patients With and Without J Waves.

INTRODUCTION: We recently showed that the presence of J waves increases the risk of ventricular fibrillation (VF) occurrence in the early phase of an acute myocardial infarction (AMI). This study aimed to evaluate the clinical characteristics of VF occurrences in the early phase of an AMI between patients with and without J waves. METHODS AND RESULTS: This retrospective, observational study included 281 consecutive patients with an AMI (69 ± 12 years; 207 men) in whom 12-lead ECGs before AMI onset could be evaluated. The patients were classified based on a VF occurrence <48 hours after AMI onset and the presence of J waves. J waves were electrocardiographically defined as an elevation of the terminal portion of the QRS complex of >0.1 mV from baseline in at least 2 contiguous inferior or lateral leads. VF occurred in 24 patients, and J waves were present in 37. VF occurrence was more prevalent in the patients with than without J waves (27% vs. 6%; P < 0.001). Among the 244 patients without J waves, peak creatine kinase level (P < 0.01), number of diseased coronary arteries (P < 0.01), and male sex (P < 0.05) were higher in the patients with than without VF occurrence. However, among the 37 patients with J waves, there was no significant difference in these variables. There was no association between the location of J waves and the infarct area. CONCLUSIONS: In patients with AMI, those with J waves were more likely to develop VF and less likely to have high-risk clinical characteristics than those without J waves.

Early repolarization increases the occurrence of sustained ventricular tachyarrhythmias and sudden death in the chronic phase of an acute myocardial infarction.

BACKGROUND: We recently showed that the presence of early repolarization (ER) increases the risk of ventricular fibrillation occurrences in the early phase of acute myocardial infarction (AMI). This study aimed to clarify whether an association exists between ER and occurrences of ventricular tachyarrhythmias or sudden death in the chronic phase of AMI. METHODS AND RESULTS: This study retrospectively enrolled 1131 patients (67±12 years; 862 men) with AMIs surviving 14 days post-AMI. The primary end point was the occurrence of sustained ventricular tachyarrhythmias or sudden death >14 days after the AMI onset. We evaluated the presence of ER from the predischarge ECG (mean 10±3 days post-AMI). ER was defined as an elevation of the terminal portion of the QRS complex of >0.1 mV in inferior or lateral leads. After a median follow-up of 26.2 months, 26 patients had an episode of ventricular tachyarrhythmias or sudden death. A multivariable Cox regression analysis revealed the presence of ER (hazard ratio, 5.37; 95% confidence interval, 2.27-12.69; P<0.001), Killip class on admission of >I (hazard ratio, 2.75; 95% confidence interval, 1.24-6.07; P=0.013), and a left ventricular ejection fraction of <35% (hazard ratio, 11.83; 95% confidence interval, 5.16-27.13; P<0.001) were significantly associated with event occurrences. As features of the ER pattern, ER in the inferior leads, high-amplitude ER, a notched morphology, and ER without ST-segment elevation were associated with an increased risk of event occurrences. CONCLUSIONS: ER observed at a mean of 10 days post-AMI may be a marker for a subsequent risk of ventricular tachyarrhythmias or sudden death.

Organ fusion and defective shoot development in oni3 mutants of rice.

Maintenance of organ separation is one of the essential phenomena for normal plant development. We have identified and analyzed ONION3 (ONI3), which is required for avoiding organ fusions in rice. Loss-of-function mutations of ONI3, which were identified as mutants with ectopic expression of KNOX genes in leaves and morphologically resembling KNOX overexpressors, showed abnormal organ fusions in developing shoots. The mutant seedlings showed fusions between neighboring organs and also within an organ; they stopped growing soon after germination and subsequently died. ONI3 was shown to encode an enzyme that is most similar to Arabidopsis HOTHEAD and is involved in biosynthesis of long-chain fatty acids. Expression analyses showed that ONI3 was specifically expressed in the outermost cell layer in the shoot apex throughout life cycle, and the oni3 mutants had an aberrant outermost cell layer. Our results together with previous studies suggest that long-chain fatty acids are required for avoiding organ fusions and promoting normal shoot development in rice.

Triple antithrombotic therapy is the independent predictor for the occurrence of major bleeding complications: analysis of percent time in therapeutic range.

BACKGROUND: Triple antithrombotic therapy increases the risk of bleeding events in patients undergoing percutaneous coronary intervention. However, it remains unclear whether good control of percent time in therapeutic range is associated with reduced occurrence of bleeding complications in patients undergoing triple antithrombotic therapy. METHODS AND RESULTS: This study included 2648 patients (70 ± 11 years; 2037 men) who underwent percutaneous coronary intervention with stent in the Ibaraki Cardiovascular Assessment Study registry and received dual antiplatelet therapy with or without warfarin. Clinical end points were defined as the occurrence of major bleeding complications (MBC), major adverse cardiac and cerebrovascular event, and all-cause death. Among these 2648 patients, 182 (7%) patients received warfarin. After a median follow-up period of 25 months (interquartile range, 15-35 months), MBC had occurred in 48 (2%) patients, major adverse cardiac and cerebrovascular event in 484 (18%) patients, and all-cause death in 206 (8%) patients. Multivariable Cox regression analysis revealed that triple antithrombotic therapy was the independent predictor for the occurrence of MBC (hazard ratio, 7.25; 95% confidence interval, 3.05-17.21; P<0.001). The time in therapeutic range value did not differ between the patients with and without MBC occurrence (83% [interquartile range, 50%-90%] versus 75% [interquartile range, 58%-87%]; P=0.7). However, the mean international normalized ratio of prothrombin time at the time of MBC occurrence was 3.3 ± 2.1. Triple antithrombotic therapy did not have a predictive value for the occurrence of all-cause death (P=0.1) and stroke (P=0.2). CONCLUSIONS: Triple antithrombotic therapy predisposes patients to an increased risk of MBC regardless of the time in therapeutic range.

ONION2 fatty acid elongase is required for shoot development in rice.

A plant's surface is covered with epicuticular wax, which protects plants from inappropriate environmental conditions such as drought and pathogen attack. Very-long-chain fatty acids (VLCFAs) are the main component of epicuticular wax on the surface of above-ground organs. Here we show that a fatty acid elongase catalyzing an elongation reaction of VLCFAs is required for shoot development in rice. onion2 (oni2) mutants produced very small shoots in which leaves were fused to each other, and ceased growing after germination. The midrib of oni2 leaf blades was not developed correctly. Molecular cloning showed that ONI2 encodes a fatty acid elongase, which catalyzes the first step of elongation reactions of a carbon chain of VLCFAs, and oni2 had a reduced amount of VLCFAs. Expression analysis showed that ONI2 is specifically expressed in the outermost cell layer of young lateral organs. These results suggest that ONI2 is a layer 1-specific gene required for development of the entire shoot and that VLCFAs play an essential role in normal shoot development in rice.