Meiso Hayashi

Out‐of‐hospital cardiac arrest (OHCA) is a global public health problem, with survival rates remaining low at around 10% or less despite widespread cardiopulmonary resuscitation (CPR) training and availability of automated external defibrillators (AEDs). This is partly due to the challenges of knowing when and where a sudden OHCA occurs and where the nearest AED is located. In response, countries around the world have begun to use network technology‐based smartphone applications. These applications are activated by emergency medical service dispatchers and alert preregistered volunteer first responders (VFRs) to nearby OHCAs using Global Positioning System localization. Accumulating evidence, although mostly from observational studies, shows their effectiveness in increasing the rate of bystander CPR, defibrillation, and patient survival. Current guidelines recommend the use of these VFR alerting systems, and the results of ongoing randomized trials are awaited for further dissemination. This article also proposed the concept of a life‐saving mobile network (LMN), which uses opportunistic network and wireless sensor network technologies to create a dynamic mesh network of potential victims, rescuers, and defibrillators. The LMN works by detecting a fatal arrhythmia with a wearable sensor device, localizing the victim and the nearest AED with nearby smartphones, and notifying VFRs through peer‐to‐peer communication. While there are challenges and limitations to implementing the LMN in society, this innovative network technology would reduce the tragedy of sudden cardiac death from OHCA.

Introduction The concept of a 3‐month blanking period is widely accepted after the first radiofrequency catheter ablation (RFCA) session for atrial fibrillation (AF). We sought to investigate whether this phenomenon was also observed after a 2nd session, and which factors were related to it. Methods and Results We conducted a prospective observational study including all AF patients who underwent RFCA since 2010. The patients who underwent a second RFCA were followed without any antiarrhythmic drugs. Their clinical background, laboratory data, echocardiographic parameters, ablation procedures, and arrhythmia recurrences were analyzed. Recurrences were classified into early period recurrences (EPRs) and late period recurrences (LPRs) recorded within and after the first 3 months postablation, respectively. Among 925 patients who underwent an initial AF ablation, 2nd sessions were performed in 250 patients, and EPRs and LPRs occurred in 53 (21.2%) and 54 (21.6%) patients, respectively. Although EPRs were an independent predictor of LPRs (hazard ratio [HR], 8.01; 95% confidence interval [CI] 4.03–15.93, P < 0.001), 20 of the patients with EPRs (37.7%) did not experience LPRs, supporting the concept of a blanking period. Among 53 patients with EPRs, the E/E′ ratio on echocardiography (HR, 1.156; 95% CI 1.00–1.33, P = 0.04) was an independent predictor of LPRs, while other parameters including the maximum serum C‐reactive protein level after the session and the ablation procedure details were not. Conclusion A 3‐month blanking period was also applicable after the 2nd AF ablation session. This phenomenon was related to a lower left atrial pressure demonstrated by the E/E′ ratio.

Background: Urgent catheter ablation is often required for various tachyarrhythmias; however, its efficacy and safety in elderly patients have not been fully elucidated. Methods: This study included consecutive octogenarians who underwent urgent radiofrequency catheter ablation (RFCA) for various serious tachyarrhythmias (urgent group, n=28) that were life threatening, hemodynamically deleterious, or provoking ischemia, and consecutive octogenarians who underwent elective RFCA (control group, n=36). The rate of a successful RFCA, complications, later arrhythmia recurrences, and mortality were compared between the groups. Results: There was no significant difference in the breakdown of the targeted arrhythmias between the groups, and common-type atrial flutter was most often targeted in both the urgent group (57%) and the elective group (56%). Compared with the control group patients, the patients of the urgent group were older (84 +/- 3 vs. 82 +/- 2 years P=0.001), with a higher frequency of baseline heart disease (68% vs. 17%, P <0.001) and lower left ventricular ejection fraction (45% +/- 15% vs. 68% +/- 10%, P<0.001). The rates of acute success (100% vs. 100%, P=1.00) and later arrhythmia recurrences (4% vs. 14%, P=0.22) were comparable between the groups. Two patients in the urgent group and 2 in the elective group had procedure-related nonlethal complications (7% vs. 6%, P=1.00): groin hematoma in 2, pressure ulcer in 1, and CO2 narcosis in 1. There were no in-hospital deaths, and mortality during follow-up did not differ between the urgent and elective groups (6.0% vs. 3.9% per year, log-rank P=0.38). Conclusion: Even in octogenarian patients, urgent catheter ablation for serious tachyarrhythmias can be safely performed with a high success rate and acceptable prognosis.

Catheter ablation of atrial fibrillation (AF) in patients with hypertrophic cardiomyopathy (HCM) is still challenging, and it is unclear whether the difficulty is caused by the hypertrophy of left atrial (LA) myocardial wall thickness. The objective of the study was to compare the LA wall thickness and AF ablation outcomes between patients with HCM and those without structural heart disease. The present study enrolled 17 consecutive HCM patients (63 ± 12 years) with drug-refractory AF and 34 control patients without any detectable heart disease, whose age, gender, type of AF, and LA dimension were matched to the HCM patients. The myocardial wall thickness of 11 distinct LA locations, measured using 64-slice computed tomography images, and AF ablation outcomes were compared between the two groups. The LA wall thickness did not differ at 9 of the 11 locations and was significantly thinner in the HCM patients than in the control patients at the mid-posterior wall (1.44 ± 0.17 vs. 1.58 ± 0.22, p = 0.04) and infero-posterior wall (1.62 ± 0.16 vs. 1.74 ± 0.18, p = 0.03). Although antiarrhythmic drugs were used more frequently in the HCM patients (p = 0.008), the rate of maintaining sinus rhythm during the follow-up did not differ between the HCM and control patients (53 vs. 56 % after the initial ablation [log-rank p = 0.78] and 82 and 88 % after the repeat procedure [log-rank p = 0.35]). The LA wall in the HCM patients with AF was not thicker than that of the matched patients without structural heart disease. Catheter ablation of AF showed favorable outcomes in both patient groups.

Atrial tachyarrhythmias (AT) commonly recur within the first 3 months after radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF), and the influence of antiarrhythmic drugs (AADs) on the recurrences has not been fully elucidated. We sought to evaluate the efficacy of a 3-month lower-dose flecainide regime on early and late recurrences of ATs. We randomly assigned 126 patients, who underwent RFCA for AF, to the flecainide group (150 or 100 mg/day according to their body weight) or to the control group receiving no AADs. The primary endpoint was any AT lasting for ≥30 s during the first 3 months and the secondary endpoint was a composite of ATs lasting for ≥24 h or requiring cardioversion or hospitalization during the same period. All AADs were stopped after the first 3 months and the late arrhythmia recurrences were also evaluated. The primary endpoint rates were 37 and 41% in the flecainide (143 ± 19 mg/day) and control groups, respectively (log-rank P = 0.76), and those of the secondary endpoint were 10 and 14%, respectively (log-rank P = 0.45). The estimated rates of maintaining sinus rhythm at 12 months after the first 3 months were 78 and 72%, in the flecainide and control groups, respectively (log-rank P = 0.68), and the rates were 51 and 90% in those with and without the primary endpoint, respectively (log-rank P < 0.001). The 3-month lower-dose flecainide therapy after AF ablation did not reduce the early and late arrhythmia recurrences. The clinically significant ATs were also not prevented.

Ventricular tachycardia (VT) and ventricular fibrillation (VF) are not uncommon in patients hospitalized with acute heart failure (AHF). We sought to evaluate the efficacy of urgent radiofrequency catheter ablation (RFCA) for recurrent VT/VF during AHF decompensations. The present study retrospectively analysed the data of 15 consecutive patients (69 ± 9 years, ischaemic heart disease in 10), who underwent urgent RFCA for frequent drug-refractory VT/VF episodes during an AHF decompensation with pulmonary congestion. The target arrhythmias were clinically documented monomorphic VTs in 10 patients, frequent premature ventricular contractions (PVCs) triggering VF in 4, and both in 1. The mean left ventricular ejection fraction was 26 ± 8%. The maximum number of arrhythmia episodes over 24 h was 9.1 ± 11.7. All RFCA sessions were completed without any major complications except for a temporary deterioration of pulmonary congestion in three patients (20%). Elimination and non-inducibility of the target arrhythmias were achieved in 13 patients (87%). Successful ablation site electrograms showed Purkinje potentials for all 5 PVCs triggering VF and 4 of 14 clinically documented monomorphic VTs (29%). Five patients (33%) underwent second sessions 10 ± 4 days after the first session for acute recurrences. Sustained VT/VF was completely suppressed during admission in 12 patients (80%), and the AHF ameliorated in 13 patients (93%). Twelve patients (80%) were discharged alive. Urgent RFCA for drug-resistant sustained ventricular tachyarrhythmias during AHF decompensations would be an appropriate therapeutic option. Purkinje fibres can be ablation targets not only in those with PVCs triggering VF, but also in those with monomorphic VT.