Safety and Performance of the Micra VR Leadless Pacemaker in a Japanese Cohort - Comparison With Global Studies

BACKGROUND

The Micra leadless pacemaker has demonstrated favorable outcomes in global trials, but its real-world performance and safety in a Japan-specific population is unknown.Methods and Results: Micra Acute Performance (MAP) Japan enrolled 300 patients undergoing Micra VR leadless pacemaker implantation in 15 centers. The primary endpoint was the acute (30-day) major complication rate. The 30-day and 6-month major complication rates were compared to global Micra studies. All patients underwent successful implantation with an average follow-up of 7.23±2.83 months. Compared with previous Micra studies, Japanese patients were older, smaller, more frequently female, and had a higher pericardial effusion risk score. 11 acute major complications were reported in 10 patients for an acute complication rate of 3.33% (95% confidence interval: 1.61-6.04%), which was in line with global Micra trials. Pericardial effusion occurred in 4 patients (1.33%; 3 major, 1 minor). No procedure or device-related deaths occurred. Frailty significantly improved from baseline to follow-up as assessed by Japan Cardiovascular Health Study criteria.

CONCLUSIONS

In a Japanese cohort, implantation of the Micra leadless pacemaker had a high success rate and low major complication rate. Despite the Japan cohort being older, smaller, and at higher risk, the safety and performance was in line with global Micra trials.

Registry for Evaluating Healthy Life Expectancy and Long-Term Outcomes after Catheter Ablation of Atrial Fibrillation in the Very Elderly (REHEALTH AF) study: rationale and design of a prospective, multicentre, observational, comparative study

INTRODUCTION

Data are lacking on the extent to which patients with non-valvular atrial fibrillation (AF) who are aged ≥80 years benefit from ablation treatment. The question pertains especially to patients' postablation quality of life (QoL) and long-term clinical outcomes.

METHODS AND ANALYSIS

We are initiating a prospective, registry-based, multicentre observational study that will include patients aged ≥80 years with non-valvular AF who choose to undergo treatment by catheter ablation and, for comparison, such patients who do not choose to undergo ablation (either according to their physician's advice or their own preference). Study subjects are to be enrolled from 52 participant hospitals and three clinics located throughout Japan from 1 June 2022 to 31 December 2023, and each will be followed up for 1 year. The planned sample size is 660, comprising 220 ablation group patients and 440 non-ablation group patients. The primary endpoint will be the composite incidence of stroke/transient ischaemic attack (TIA) or systemic embolism (SE), another cardiovascular event, major bleeding and/or death from any cause. Other clinical events such as postablation AF recurrence, a fall or bone fracture will be recorded. We will collect standard clinical background information plus each patient's Clinical Frailty Scale score, AF-related symptoms, QoL (Five-Level Version of EQ-5D) scores, Mini-Mental State Examination (optional) score and laboratory test results, including measures of nutritional status, on entry into the study and 1 year later, and serial changes in symptoms and QoL will also be secondary endpoints. Propensity score matching will be performed to account for covariates that could affect study results.

ETHICS AND DISSEMINATION

The study conforms to the Declaration of Helsinki and the Ethical Guidelines for Clinical Studies issued by the Ministry of Health, Labour and Welfare, Japan. Results of the study will be published in one or more peer-reviewed journals.

TRIAL REGISTRATION NUMBER

UMIN000047023.

Different Determinants of the Recurrence of Atrial Fibrillation and Adverse Clinical Events in the Mid-Term Period After Atrial Fibrillation Ablation

BACKGROUND

It is unclear whether there are differences in the clinical factors between atrial fibrillation (AF) recurrence and adverse clinical events (AEs), including stroke/transient ischemic attack (TIA), major bleeding, and death, after AF ablation.Methods and Results:We examined the data from a retrospective multicenter Japanese registry conducted at 24 cardiovascular centers between 2011 and 2017. Of the 3,451 patients (74.1% men; 63.3±10.3 years) who underwent AF ablation, 1,046 (30.3%) had AF recurrence and 224 (6.5%) suffered AEs (51 strokes/TIAs, 71 major bleeding events, and 36 deaths) over a median follow-up of 20.7 months. After multivariate adjustment, female sex, persistent and long-lasting persistent AF (vs. paroxysmal AF), and stepwise increased left atrial diameter (LAd) quartiles were significantly associated with post-ablation recurrences. A multivariate analysis revealed that an age ≥75 years (vs. <65 years), body weight <50 kg, diabetes, vascular disease, left ventricular (LV) ejection fraction <40% (vs. ≥50%), Lad ≥44 mm (vs. <36 mm), and creatinine clearance <50 mL/min were independently associated with AE incidences, but not with recurrences.

CONCLUSIONS

This study disclosed different determinants of post-ablation recurrence and AEs. Female sex, persistent AF, and enlarged LAd were determinants of post-ablation recurrence, whereas an old age, comorbidities, and LV and renal dysfunction rather than post-ablation recurrence were AEs determinants. These findings will help determine ablation indications and post-ablation management.

Clinical outcomes of ablation versus non-ablation therapy for atrial fibrillation in Japan: analysis of pooled data from the AF Frontier Ablation Registry and SAKURA AF Registry

Whether ablation for atrial fibrillation (AF) is, in terms of clinical outcomes, beneficial for Japanese patients has not been clarified. Drawing data from 2 Japanese AF registries (AF Frontier Ablation Registry and SAKURA AF Registry), we compared the incidence of clinically relevant events (CREs), including stroke/transient ischemic attack (TIA), major bleeding, cardiovascular events, and death, between patients who underwent ablation (n = 3451) and those who did not (n = 2930). We also compared propensity-score matched patients (n = 1414 in each group). In propensity-scored patients who underwent ablation and those who did not, mean follow-up times were 27.2 and 35.8 months, respectively. Annualized rates for stroke/TIA (1.04 vs. 1.06%), major bleeding (1.44 vs. 1.20%), cardiovascular events (2.15 vs. 2.49%) were similar (P = 0.96, 0.39, and 0.35, respectively), but annualized death rates were lower in the ablation group than in the non-ablation group (0.75 vs.1.28%, P = 0.028). After multivariate adjustment, the risk of CREs was statistically equivalent between the ablation and non-ablation groups (hazard ratio [HR] 0.89, 95% confidence interval [CI] 0.71-1.11), but it was significantly low among patients who underwent ablation for paroxysmal AF (HR 0.68 [vs. persistent AF], 95% CI 0.49-0.94) and had a CHA₂DS₂-VASc score  < 3 (HR 0.66 [vs. CHA₂DS₂-VASc score ≥ 3], 95% CI 0.43-0.98]). The 2-year risk reduction achieved by ablation may be small among Japanese patients, but AF ablation may benefit those with paroxysmal AF and a CHA₂DS₂-VASc score < 3.

Simple and novel technique to confirm complete mitral isthmus block

BACKGROUND

Differential pacing technique to confirm mitral isthmus (MI) block is sometimes challenging due to destroyed tissues after extensive ablation. The purpose of this study is to set an endpoint of MI ablation using conduction time around the mitral annulus (MA).

METHODS

Forty-five consecutive patients with persistent atrial fibrillation who received MI linear ablation were included. The geometry and activation times of the left atrium around the MA were collected using a multipolar catheter before ablation. During coronary sinus (CS) pacing, the time between the stimulus and the wave-front collision at the opposite side of the MA (defined as T/2) was calculated, and the doubled value was defined as the estimated perimitral conduction time (E-PMCT). The endpoint for complete MI block was when the stimulus (at distal CS) minus the maximal delayed potential (St-MDP) on the MI interval reached the E-PMCT.

RESULTS

St-MDP reached E-PMCT during MI ablation in 44/45 patients. Among these 44 patients, differential pacing revealed bidirectional block in 39/44 (88.6%), whereas in 5/44 (11.4%), the differential pacing was not possible because of the loss of capture of local potentials due to extensive applications around the linear line. In one patient, the St-MDP did not reach E-PMCT (E-PMCT: 148 ms, St-MDP :130 ms) and differential pacing revealed no MI block. E-PMCT values (median 176 ms) correlated strongly with St-MDP (median 185 ms, P < 0.0001, R = 0.98).

CONCLUSIONS

Although E-PMCT differs between individuals, the value is significantly correlated with the St-MDP. This technique may be useful in providing an individual endpoint of MI ablation as an alternative to differential pacing.

The proportion of asymptomatic recurrence after catheter ablation of atrial fibrillation in patients with a pacemaker for sick sinus syndrome

Background

Catheter ablation (CA) of paroxysmal atrial fibrillation (PAF) is an effective treatment. However, the frequency of asymptomatic AF recurrence after CA in patients with PAF and sick sinus syndrome (SSS) is not clear. The aim of this study was to elucidate the real AF recurrence after CA in patients with PAF and a pacemaker for SSS.

Methods and results

Fifty-one consecutive patients (mean age 66.6 ± 7.0 years, male 34) with PAF and SSS and pacemakers underwent CA. All patients were followed at 1, 3, 6, 9, and 12 months after the CA using a 12-lead ECG, Holter-ECG, and 1-month event recorder as a conventional follow-up. In addition, the pacemakers were interrogated every 12 months. During a 5-year follow-up after the final CA procedure, AF recurrences were observed in 7 patients (13.7%) with a conventional follow-up, including 1 (2.0%) asymptomatic patient. Pacemaker-interrogation revealed another 10 patients (19.6%) with asymptomatic AF recurrences. Ultimately, the conventional follow-up plus pacemaker-interrogation provided a higher incidence of AF recurrences (P = 0.009). Multiple CA procedures contributed to a significant increase in the AF-free survival rate at 5 years: 58.6% after a single CA and 86.0% after multiple CA procedures with a conventional follow-up, but which decreased to 40.6% and 60.9% with a conventional follow-up plus a pacemaker interrogation, respectively.

Conclusions

One-third of PAF patients with SSS and pacemakers recurred after multiple CA sessions. However, 65% of them were asymptomatic and difficult to be identified with conventional follow-up. Pacemaker interrogation significantly increased the detection rate of AF-recurrence.

Airway support using a pediatric intubation tube in adult patients with atrial fibrillation: A simple and unique method to prevent heart movement during catheter ablation under continuous deep sedation

Background

The present study aimed to elucidate the safety and effectiveness of a noble and unique airway management technique in which a pediatric intubation tube is used in adult patients with atrial fibrillation (AF) undergoing catheter ablation (CA) under continuous deep sedation.

Methods

In total, 246 consecutive patients with AF (mean age, 65±10 years; 60 women) underwent CA under dexmedetomidine-based continuous deep sedation. A 4-mm pediatric intubation tube guided by a 10-French intratracheal suction tube was inserted smoothly, and the tip of the tube was located at the base of the epiglottis. The maximum shifting distance of the heart (MSDH) was measured with the 3D mapping system (Ensite NavX system) before and after inserting the pediatric intubation tube.

Results

At baseline, the MSDH of patients under continuous deep sedation was 23±14 mm. The pediatric intubation tube reduced the MSDH to 13±6 mm (mean reduction from baseline, 38.4±21.7%; P<0.0001). In contrast, oxygen saturation was significantly increased from 89±8% to 95±3% (P<0.0001). The mean distance between the nostril and base of the epiglottis was 16.6±0.5 mm. Major periprocedural complications occurred in 9 (3.6%) patients including 3 (1.2%) cardiac tamponade and 6 (2.4%) phrenic nerve injury cases. Larger MSDH (odds ratio, 1.13; 95% confidence interval, 1.04–1.25; P=0.007) was a significant predictor of major periprocedural complications. No major airway complications occurred, except in 3 patients (1.2%) who had minor nasal bleeding.

Conclusion

This unique airway management technique using a pediatric intubation tube for CA procedures performed in adult patients with AF under continuous deep sedation was easy, safe, and effective.

Impact of Alcohol Consumption on the Outcome of Catheter Ablation in Patients With Paroxysmal Atrial Fibrillation

BACKGROUND

Although several studies have reported an association between atrial fibrillation (AF) and alcohol, the impact of alcohol consumption on the outcome after catheter ablation (CA) for AF has not been discussed. We aimed to elucidate the effect of alcohol consumption on the outcome of CA for paroxysmal AF.

METHODS AND RESULTS

We examined 1361 consecutive patients with paroxysmal AF (mean age, 61±11 years, 334 women) who underwent CA, including 623 (45.8%) patients who consumed alcohol. The clinical characteristics and outcomes of CA were compared between patients who did and did not consume alcohol. No significant differences were seen in the left atrial size, duration of AF history, and incidence of nonpulmonary vein foci between 2 groups (P=NS). Although the AF recurrence-free rate after the initial CA was higher in patients who did not consume alcohol (261/623 [41.9%] versus 252/738 [34.1%]; mean follow-up, 44.4±30.7 months; P=0.003), the outcome after the final CA was similar between 2 groups (patients who consumed alcohol: 111/628 [17.7%] versus patients who did not consume alcohol: 138/738 [18.7%]; mean follow-up, 53.1±25.8 months; P=0.67). The frequency (hazard ratio 1.07 per 1 day/week increase, CI 1.00-1.15, P=0.04) of alcohol consumption was significantly associated with AF recurrence after CA.

CONCLUSIONS

The frequency of alcohol consumption may be associated with AF recurrence after the initial CA for paroxysmal AF, but it may not affect the outcome after the final CA.

The mechanism of mitral regurgitation assessed by preprocedural echocardiography is associated with the outcome of catheter ablation in patients with paroxysmal atrial fibrillation

BACKGROUND

Mitral regurgitation (MR) is generally classified as either primary (organic) or secondary (functional). Although patients with atrial fibrillation (AF) often exhibit MR, the relation between the etiology of MR and the outcome of catheter ablation (CA) remains unknown. We conducted this study in order to elucidate this association.

METHODS

Among 1330 consecutive paroxysmal AF patients who underwent initial catheter ablation in our institution, 92 patients (62 men, mean age 65 ± 7 years) who had moderate or severe MR were included in this study; 46 were classified to have primary and the remaining 46 to have secondary MR by preoperative echocardiography. These patients were prospectively monitored after the CA.

RESULTS

During a mean follow-up period of 27.9 ± 28.8 months, AF recurred in 26/46 (56.6 %) of primary MR patients and in 15/46 (32.6 %) of those with secondary MR (P < 0.02). Although univariate analysis found that diabetes, left atrial volume indexed by body surface area (LAVI), and primary MR were significantly associated with AF recurrence, primary MR (hazard ratio (HR), 2.47; 95 % confidence interval (CI), 1.30-4.88; P = 0.006) and LAVI (HR, 1.03/1 mL/m(2) increase; 95 % CI, 1.00-1.06; P = 0.03) remained significant predictors on multivariate analysis. The AF recurrence-free rate was lower in patients with primary MR after both the initial and final CA.

CONCLUSION

In patients with paroxysmal AF and moderate or severe MR, primary MR may increase the risk of AF recurrence after the initial and final CA.

Rapid Mapping of Right Atrial Tachycardia Using a New Multielectrode Basket Catheter

INTRODUCTION

The mapping of atrial tachycardia (AT) can often be challenging and time-consuming, especially in patients with ATs that develop following cardiac surgery or are concomitant with atrial fibrillation. Recently, a new multielectrode basket catheter (MBC) has become available; we hypothesized that the MBC could be utilized to diagnose AT circuits.

METHODS AND RESULTS

This study included 51 consecutive patients undergoing catheter ablation of clinically documented right-sided ATs (including 17 cases following cardiac surgery). Using a NavX system, 2 activation maps of the ATs were created, one using the new MBC (32 mm, 31 poles) and the other using a circular catheter. The time needed to complete the activation maps and the points acquired with both mapping catheters were compared. In all 64 ATs, including 34 non-cavotricuspid isthmus-dependent ATs, the AT activation maps created by both catheters were essentially identical. The number of points acquired to complete the activation maps did not differ significantly between the MBC and the circular catheter (387 [285-511] vs. 374 [269-533], P = 0.19), but the mapping time was significantly shorter using the MBC (4.0 [3.0-6.0] minutes vs. 8.0 [6.5-10.0] minutes, P < 0.0001). Inadvertent mechanical AT termination (n = 6) was observed only during mapping with the circular catheter.

CONCLUSION

In patients with right-sided ATs, the use of an MBC could save mapping time.

Relation between dabigatran concentration, as assessed using the direct thrombin inhibitor assay, and activated clotting time/activated partial thromboplastin time in patients with atrial fibrillation

Dabigatran is a direct thrombin inhibitor that has been approved for preventing stroke in patients with atrial fibrillation. In this study, we aimed to assess the associations between the dabigatran concentration (calculated through plasma-diluted thrombin time, as assessed using the Hemoclot assay) and the activated partial thromboplastin time (aPTT) and activated clotting time (ACT). We recruited 137 patients with atrial fibrillation who were receiving a normal dose of dabigatran (300 mg/d) or a reduced dose of dabigatran (220 mg/d, usually administered to patients who were elderly, had moderate renal dysfunction, or who were also receiving verapamil). We then assessed the aPTT, ACT, and Hemoclot results of the patients and calculated the plasma dabigatran concentration. The mean plasma concentration of dabigatran was 127 ± 88 ng/ml, although no significant differences in dabigatran concentration, ACT, or aPTT were observed when we compared the 2 doses of dabigatran (300 or 220 mg/d). The dabigatran concentration was within the therapeutic levels in most patients, although a high value (>300 ng/ml) was observed in several patients, which indicated a high risk of bleeding. The dabigatran concentration was strongly and positively correlated with ACT and aPTT (r = 0.87, p <0.001; and r = 0.76, p <0.001; respectively). Multivariate analysis revealed that verapamil use was independently associated with elevated dabigatran concentrations (p <0.001). Therefore, ACT and aPTT may be useful for bedside assessment of the anticoagulant activity of dabigatran, and verapamil use may be a risk factor for elevated dabigatran concentrations.

Simultaneous isolation of superior and inferior pulmonary veins on both the left and right sides could yield better outcomes in patients with paroxysmal atrial fibrillation

AIMS

This study investigated whether disappearance patterns of pulmonary vein (PV) potentials (PVPs) during PV isolation (PVI) affect the outcome of catheter ablation (CA) in patients with paroxysmal atrial fibrillation (PAF).

METHODS AND RESULTS

Extensive PVI was performed in 1149 PAF patients (age, 61 ± 10 years). Clinical and demographic characteristics, ablation data, and follow-up outcomes were prospectively collected. During an initial CA, simultaneous disappearance of superior and inferior PVPs in both right and left PVs was observed in 464 (40.4%) patients (Group S). Atrial fibrillation-recurrence free rates at 1, 3, and 5 years after the initial CA in Group S were 78.9, 71.9, and 68.1%, respectively, which were higher than those in Group Non-S (P = 0.004). However, those were similar after the final CA between both groups. The incidence of PV-left atrium (LA) electrical reconnection was significantly lower in Group S than in Group Non-S in the second (Group S, 65.6% vs. Group Non-S, 82.1%; P = 0.004) and third (Group S, 8.3% vs. Group Non-S, 47.6%; P = 0.03) CAs. Furthermore, the reconnections more frequently occurred on the side of PVs where simultaneous PVP elimination had not been achieved at the initial CA. Simultaneous disappearance of superior and inferior PVPs in both right and left PVs independently reduced the risk of AF recurrence after the initial CA by 26%.

CONCLUSIONS

The simultaneous disappearance of superior and inferior PVPs in both right and left PVs is associated with less frequent PV-left atrium reconnection and may yield a better clinical outcome after the initial CA.

Late-phase thromboembolism after catheter ablation for paroxysmal atrial fibrillation

BACKGROUND

The aim of this study was to investigate the incidence and predictors (which have not previously been fully elucidated) of late-phase thromboembolism (TE) after catheter ablation (CA) for paroxysmal atrial fibrillation (AF).

METHODS AND RESULTS

We studied 1,156 consecutive patients (61±10 years; 891 men; CHADS2score, 0.8±1.0) after CA for symptomatic paroxysmal AF and examined the details of late-phase TE. During a follow-up of 49.5±21.9 months (median, 47 months; range, 6-113 months) after CA, 9 patients (0.78%) developed late-phase TE, all of which were ischemic stroke. Of these, 5 patients with AF recurrence experienced cardioembolism; the AF was asymptomatic at recurrence. The remaining 4 without AF recurrence experienced cardioembolism (n=1), small-vessel occlusion (n=1), large-artery atherosclerosis (n=1), and stroke of other determined etiology (n=1). On Kaplan-Meier analysis patients with structural heart disease (P=0.003), AF recurrence after the final CA (P=0.01), prior stroke (P=0.002), CHADS2score ≥2 (P=0.0002), left ventricular ejection fraction <50% (P<0.0001), and spontaneous echo contrast on transesophageal echocardiogram (P=0.0004) had a significantly higher risk of late-phase TE. Multivariate analysis indicated that CHADS2score ≥2 (HR, 4.49; 95% CI: 1.08-22.56; P=0.04) independently predicted late-phase TE.

CONCLUSIONS

The incidence of TE was low after CA for paroxysmal AF, but CHADS2score ≥2 independently increased the risk of late-phase TE.

Long-Term Follow-Up After Catheter Ablation of Paroxysmal Atrial Fibrillation

Background—

Although catheter ablation (CA) is a standard treatment for atrial fibrillation (AF), its long-term efficacy remains unclear. This study aimed to elucidate the incidences of AF recurrence and of progression from paroxysmal to persistent AF, after CA, in patients with paroxysmal AF.

Methods and Results—

We examined the incidence of AF recurrence and AF progression in 1220 consecutive patients (mean age, 61 years), with symptomatic paroxysmal AF, undergoing CA, based on extensive pulmonary vein isolation and focal ablation for nonpulmonary vein foci. AF recurrence–free survival probabilities at 5 years were 59.4% after the initial CA and 81.1% after the final CA (average, 1.3 procedures). During a median follow-up period of 47.9 (range, 5.3–123.3) months after the initial CA, AF progressed from paroxysmal to persistent in 15 (1.2%) patients (0.3%/y). The duration of AF history (hazard ratio [HR], 1.03; P <0.0001), number of ineffective antiarrhythmics (HR, 1.09; P =0.005), and left atrial diameter indexed by the body surface area (HR, 1.05; P =0.001) were significant predictors of AF recurrence. Patient age (HR, 1.12; P =0.0001) and left atrial diameter indexed by the body surface area (HR, 1.26; P =0.0006) were significantly associated with AF progression. Patients aged ≤65 years and with a left atrial diameter indexed by the body surface area of ≤24.0 mm/m 2 did not develop AF progression for ≤10 years after the initial CA.

Conclusions—

Although the long-term follow-up revealed the effect of CA on preventing AF recurrence, repeated CA sessions might be required. The rate of progression from paroxysmal to persistent AF was 0.3%/y.

The impact of haemodialysis on the outcomes of catheter ablation in patients with paroxysmal atrial fibrillation

AIMS

The outcomes of catheter ablation (CA) in patients with paroxysmal atrial fibrillation (PAF) who are undergoing haemodialysis (HD) have not been fully elucidated. This study aimed to determine the impact of HD on CA outcome in these patients.

METHODS AND RESULTS

We examined 1364 consecutive PAF patients (mean age, 61 ± 10 years) who underwent CA, including 32 (2.3%) patients undergoing HD. The patients undergoing HD had a significantly lower body mass index (P < 0.0001), higher CHADS2 score (P = 0.006), and higher prevalence of structural heart disease (P < 0.0001), hypertension (P = 0.002), and congestive heart failure (P = 0.02). Echocardiography indicated a larger left atrial diameter (P < 0.0001) and left ventricular diameter (P = 0.0002) in the HD patients. Haemodialysis was a significant predictor of AF recurrence (hazard ratio 2.56; 95% confidence interval 1.56-4.03; P = 0.0004) in the overall population. Sinus rhythm maintenance rates in the HD patients at 1, 3, and 5 years were 42.3, 37.6, and 19.7%, respectively, after the first procedure, and 64.7, 54.9, and 47.1%, respectively, after the final procedure (median, 2; range, 1-2 procedures); these rates were significantly lower than those in the non-HD patients (P < 0.0001). The 5-year survival rate was 78.1% in the HD patients.

CONCLUSION

Haemodialysis was significantly associated with AF recurrence after CA for PAF. However, an ∼50% success rate for sinus rhythm maintenance without antiarrhythmic drug therapy in HD patients suggested that CA could be an option for the treatment of AF.

Takotsubo cardiomyopathy in siblings

We report the case of apical ballooning syndrome (ABS) in a female sibling. A 64-year-old woman was admitted to our hospital with sudden-onset chest pain. Cardiac enzymes were mildly elevated and an electrocardiogram showed broad ST-T changes. Emergency coronary angiography revealed no culprit lesion and left ventriculography demonstrated focal akinesis of the apical wall, which was consistent with ABS. Myocardial functional sympathetic innervations assessed using [(123)I]metaiodobenzylguanidine was severely impaired in the apical region. Her clinical symptoms and cardiac dysfunction recovered spontaneously. Just 1 year prior to our patient's cardiac event, her elder sister had the same symptoms and was also diagnosed with ABS. Both sisters were postmenopausal. The familial case of ABS is exceedingly rare, but these cases suggest a possible genetic etiology.

Differences in catheter ablation of paroxysmal atrial fibrillation between males and females

BACKGROUND

Catheter ablation (CA) has become a standard treatment for patients with atrial fibrillation (AF). However, gender-related differences associated with CA of paroxysmal AF (PAF) remain unclear.

METHODS

We compared 1124 consecutive patients (mean age, 61 ± 10 years; male, n=864) with PAF scheduled for CA between the genders.

RESULTS

Females were significantly older (p<0.0001), and had a lower body-mass-index (p=0.02), smaller left atrial dimension (LAD; p=0.04), larger LAD indexed by the body-surface-area (LADI; p<0.0001) and better left ventricular ejection fraction (p<0.0001) at baseline. Ischemic heart disease (p=0.007) was more frequent in males, whereas hypertrophic cardiomyopathy (p=0.007) and mitral stenosis (p=0.001) were more frequent in females. More additional procedures were performed to eliminate non-pulmonary vein foci in females than males (p<0.05), but those locations were similar between the genders. The incidence of procedure-related complications was similar between genders (p=0.73). Sinus rhythm was similarly maintained between females and males after the first CA (56.4% vs. 59.3% at 5 years, p=0.24), but was significantly lower in females after the last CA (76.5% vs. 81.3% at 5 years, p=0.007). More females did refuse multiple CA procedures (especially a second one) than males (37.8% in females vs. 27.4% in males, p=0.02). The age (HR, 0.98/y, p=0.01), duration of AF (HR, 1.04/y, p=0.0001), number of failed anti-arrhythmic-drugs (HR, 1.10, p=0.03) and LADI (HR, 1.89 per 10mm/m(2), p=0.001) were significantly associated with AF-recurrence in males, but not in females.

CONCLUSIONS

Specific differences and similarities between the genders were observed in PAF patients undergoing CA.

Comparison of the circadian eclosion rhythm between non-diapause and diapause pupae in the onion fly, Delia antiqua: the change of rhythmicity

When pupae of Delia antiqua were transferred to constant darkness (DD) from light-dark (LD) cycles or constant light (LL), the sensitivity to light of the circadian clock controlling eclosion increased with age. The daily rhythm of eclosion appeared in both non-diapause and diapause pupae only when this transfer was made during late pharate adult development. When transferred from LL to DD in the early pupal stage, the adult eclosion was weakly rhythmic in non-diapause pupae but arrhythmic in diapause pupae. However, the sensitivity of the circadian clock to temperature cycles or steps was higher in diapause pupae than in non-diapause pupae; in the transfer to a constant 20 degrees C from a thermoperiod of 25 degrees C (12 h)/20 degrees C (12 h) on day 10 after pupation or from chilling (7.5 degrees C) in DD, the adult eclosion from diapause pupae was rhythmic but that from non-diapause pupae arrhythmic. In a transfer to 20 degrees C from the thermoperiod after the initiation of eclosion, rhythmicity was observed in both types of pupae. The larval stage was insensitive to the effect of LD cycle initiating the eclosion rhythm. In D. antiqua pupae in the soil under natural conditions, therefore, the thermoperiod in the late pupal stage would be the most important 'Zeitgeber' for the determination of eclosion timing.

Comparison of the circadian eclosion rhythm between non-diapause and diapause pupae in the onion fly, Delia antiqua: the effect of thermoperiod

When non-diapause and diapause pupae of Delia antiqua were exposed to various thermoperiods where thermophase (T) was 25 degrees C and the cryophase (C) was 15 or 20 degrees C (TC(15) or TC(20)) in constant darkness (DD), the majority of both types of flies emerged before the rise in temperature. Eclosion time was delayed at the lower cryophase temperature. Moreover, there was a significant difference in the time of adult eclosion between non-diapause and diapause pupae; diapause pupae eclosed earlier than non-diapause pupae. When the two types of pupae were transferred to a constant low temperature (15 or 20 degrees C) after having experienced TC(15) or TC(20) 12:12 h, they showed circadian rhythmicity in eclosion. The free-running period (tau) of the eclosion rhythm changed after transfer to constant low temperatures in both non-diapause and diapause pupae, suggesting that this change represents a transient cycle until the temperature-sensitive oscillator is coupled again to the temperature-insensitive pacemaker. However, diapause pupae tended to show a shorter tau than non-diapause pupae. This observation suggests that the difference in adult eclosion time under thermoperiodic conditions between non-diapause and diapause pupae is related to their different tau s.

Taurine prevents the decrease in expression and secretion of extracellular superoxide dismutase induced by homocysteine: amelioration of homocysteine-induced endoplasmic reticulum stress by taurine

BACKGROUND

Hyperhomocysteinemia is an independent risk factor for atherosclerosis. Homocysteine has been shown to induce endoplasmic reticulum (ER) stress in vascular endothelial cells. ER stress is a condition in which glycoprotein trafficking is disrupted and unfolded proteins accumulate in the ER. ER molecular chaperons, such as GRP78, are induced and an ER resident kinase, PERK, is activated when cells are subjected to ER stress. Conversely, taurine is reported to have antiatherogenic effects by unknown mechanisms. To elucidate the mechanisms by which homocysteine induces atherosclerosis and taurine prevents it, we examined whether homocysteine and taurine affect the expression and secretion of extracellular superoxide dismutase (EC-SOD), a glycoprotein secreted from vascular smooth muscle cells (VSMCs) that protects the vascular wall from oxidative stress.

METHODS AND RESULTS

We assessed the expression of EC-SOD and GRP78 mRNA in cultured rat VSMCs by Northern blot analysis. The EC-SOD protein secreted into the culture medium was examined by Western blot analysis. Homocysteine (5 mmol/L) and other ER stress inducers, including A23187, were found to decrease EC-SOD mRNA expression and protein secretion. Furthermore, they upregulated GRP78 mRNA expression and activated PERK. Taurine (0.5 to 10 mmol/L), conversely, prevented these actions induced by homocysteine.

CONCLUSIONS

Homocysteine induces ER stress and reduces the secretion and expression of EC-SOD in VSMCs, leading to increased oxidative stress in the vascular wall. Taurine restores the secretion and expression of EC-SOD by ameliorating ER stress induced by homocysteine.

Oral taurine supplementation prevents the development of ethanol-induced hypertension in rats

Taurine is known to lower blood pressure in essential hypertension and some experimental hypertensive models. Taurine has also been reported to activate aldehyde dehydrogenase and to inhibit the elevation of plasma acetaldehyde concentration after ethanol intake. Because acetaldehyde, the first metabolite of ethanol, is suspected to be responsible for many adverse effects of alcohol consumption, we examined the effect of taurine supplementation on ethanol-induced hypertension and abnormalities in the intracellular cation metabolism in Witar-Kyoto rats. In Study 1, systolic blood pressure and intraplatelet free calcium were significantly higher in rats who received 15% ethanol in drinking water than in control rats. Oral taurine supplementation (1% taurine and 15% ethanol in drinking water) completely prevented the development of ethanol-induced hypertension. Intraerythrocyte sodium and intraplatelet free calcium were significantly decreased in taurine-supplemented rats as compared with rats who received 15% ethanol only. In Study 2, hemoglobin-associated acetaldehyde (HbAA) was measured as a marker of protein-bound acetaldehyde. HbAA was significantly elevated in rats who received 5% ethanol in drinking water as compared with control rats. Taurine supplementation (1% taurine and 5% ethanol in drinking water) significantly decreased HbAA. Our findings suggest that the oral supplementation of taurine prevents ethanol-induced hypertension by decreasing protein bound acetaldehyde and altering the cation handling by the membrane.

[Hepatotoxicity induction in mice after acute DL-lactic acid intake]

DL-Lactic acid and its salts are added to food as acidulants, pH control agents, leavening agents, nutrient supplements and seasonings. However, the basic data concerning the safety and toxicity of these compounds are insufficient. In this article, we examined induction of hepatotoxicity and nephrotoxicity in mice after acute intake of DL-lactic acid. Body weight change, serum glutamic pyruvic transaminase (SGPT) activity, serum urea nitrogen (SUN) concentration, liver and kidney weights, and renal lipid peroxide level could not be affected significantly in mice at 4 h after intraperitoneal administration of DL-lactic acid at 1.2 mmol/kg, indicating no induction of toxicity in the liver and kidney. In contrast, at 20 h after the treatment, SGPT activity, liver weight and lipid peroxide level were enhanced significantly, suggesting induction of hepatotoxicity. However, SUN concentration, kidney weight and lipid peroxide level could not be affected significantly at 20 h after the treatment, indicating no induction of nephrotoxicity.

RA-GEF, a novel Rap1A guanine nucleotide exchange factor containing a Ras/Rap1A-associating domain, is conserved between nematode and humans

A yeast two-hybrid screening for Ras-binding proteins in nematode Caenorhabditis elegans has identified a guanine nucleotide exchange factor (GEF) containing a Ras/Rap1A-associating (RA) domain, termed Ce-RA-GEF. Both Ce-RA-GEF and its human counterpart Hs-RA-GEF possessed a PSD-95/DlgA/ZO-1 (PDZ) domain and a Ras exchanger motif (REM) domain in addition to the RA and GEF domains. They also contained a region homologous to a cyclic nucleotide monophosphate-binding domain, which turned out to be incapable of binding cAMP or cGMP. Although the REM and GEF domains are conserved with other GEFs acting on Ras family small GTP-binding proteins, the RA and PDZ domains are unseen in any of them. Hs-RA-GEF exhibited not only a GTP-dependent binding activity to Rap1A at its RA domain but also an activity to stimulate GDP/GTP exchange of Rap1A both in vitro and in vivo at the segment containing its REM and GEF domains. However, it did not exhibit any binding or GEF activity toward Ras. On the other hand, Ce-RA-GEF associated with and stimulated GDP/GTP exchange of both Ras and Rap1A. These results indicate that Ce-RA-GEF and Hs-RA-GEF define a novel class of Rap1A GEF molecules, which are conserved through evolution.

Identification of Ce-AF-6, a novel Caenorhabditis elegans protein, as a putative Ras effector

Mammalian Ras proteins associate with multiple effectors, including Raf, Ral guanine nucleotide dissociation stimulator, phosphoinositide 3-kinase and AF-6. In the nematode Caenorhabditis elegans, LIN-45/Raf has been identified genetically as an effector of LET-60/Ras. To search for other effectors in C. elegans, we carried out a yeast two-hybrid screening for LET-60-associating proteins. The screening identified a novel protein, designated Ce-AF-6, which exhibited a strong structural homology with human AF-6, rat Afadin and Drosophila melanogaster Canoe and possessed both the Ras-associating (RA) domain and the PSD-95/DlgA/ZO-1 (PDZ) domain. Ce-AF-6 associated with human Ha-Ras in a GTP-dependent manner, with an efficiency comparable to that of human Raf-1 Ras-binding domain. When the effects of mutations of the Ras effector region residues were examined for associations with various effectors, Ce-AF-6 was found to possess a distinct and the most rigorous requirement for the effector region residues. These results strongly suggest that Ce-AF-6 is a putative effector of Ras that possesses a distinct recognition mechanism for association with Ras.

Identification of PLC210, a Caenorhabditis elegans phospholipase C, as a putative effector of Ras

Mammalian Ras proteins regulate multiple effectors including Raf, Ral guanine nucleotide dissociation stimulator (RalGDS), and phosphoinositide 3-kinase. In the nematode Caenorhabditis elegans, LIN-45 Raf has been identified by genetic analyses as an effector of LET-60 Ras. To search for other effectors in C. elegans, we performed a yeast two-hybrid screening for LET-60-binding proteins. The screening identified two cDNA clones encoding a phosphoinositide-specific phospholipase C (PI-PLC) with a predicted molecular mass of 210 kDa, designated PLC210. PLC210 possesses two additional functional domains unseen in any known PI-PLCs. One is the C-terminal Ras-associating domain bearing a structural homology with those of RalGDS and AF-6. This domain, which could be narrowed down to 100 amino acid residues, associated in vitro with human Ha-Ras in a GTP-dependent manner and competed with yeast adenylyl cyclase for binding Ha-Ras. The binding was abolished by specific mutations within the effector region of Ha-Ras. The other functional domain is the N-terminal CDC25-like domain, which possesses a structural homology to guanine nucleotide exchange proteins for Ras. These results strongly suggest that PLC210 belongs to a novel class of PI-PLC, which is a putative effector of Ras.

Effects of photoperiod and aging on locomotor activity rhythms in the onion fly, Delia antiqua

At photoperiods longer than 8h per 24h, adults of the day-active onion fly Delia antiqua showed a major peak of locomotor activity in the late photophase and also bursts of activity induced by lights-on or lights-off. At shorter photoperiods the activity peaks fused. After transfer from long photoperiods to constant darkness (DD), the rhythm free-ran, but only the major peak persisted. This suggests that only the major peak is controlled by the circadian pacemaker. At long photoperiods, the daily phase of the major peak occurred progressively later with age. As a result, the activity at short photoperiods often shifted from photophase to scotophase in old flies. The free-running period (tau) also changed with age; tau was shorter than 24h until 14-20 days after eclosion and thereafter became longer, but a few individuals repeated changes in tau. The phase delay of locomotor activity with age in D. antiqua would be attributable to the increase in tau.