Neutral endopeptidase inhibitor suppresses the early phase of atrial electrical remodeling in a canine rapid atrial pacing model

Introduction We examined the acute effects of neutral endopeptidase inhibitor on the hemodynamics and electrical properties of dogs subjected to rapid atrial pacing. Methods Ten beagle dogs were used and divided into two groups with and without candoxatril, a neutral endopeptidase inhibitor preadministration. Before and after the 6 hours rapid atrial pacing from the right atrial appendage, the hemodynamics, atrial effective refractory period, and monophasic action potential duration of the right atrial appendage were measured and blood samples were collected. Atrial tissue was also excised after the experiment. Results Candoxatril significantly increased plasma ANP levels (Control: 88.4 ± 50.25 vs. Candoxatril: 197.1 ± 32.09 pg/ml, p = 0.004) and prevented reductions in atrial effective refractory period and monophasic action potential duration. We further demonstrated that the treated animals exhibited significantly higher levels of atrial tissue cyclic GMP (Control: 28.1 ± 1.60 fmol/mg vs. Candoxatril: 44.5 ± 12.28 fmol/mg, p = 0.034) as well as that of plasma cyclic GMP (Control: 32 ± 5.5 vs. Candoxatril: 42 ± 7.1 pg/ml, p = 0.028). Conclusion Candoxatril suppressed the shortening of atrial effective refractory period and monophasic action potential duration in the rapid atrial pacing model. As plasma ANP and the atrial tissue levels of cyclic GMP were higher in the Candoxatril group than the control, this effect was considered to appear through the reduction of calcium overload caused by ANP and cyclic GMP

Long-term observation of fibrillation cycle length in patients under angiotensin II receptor blocker therapy for chronic atrial fibrillation

AbstractIntroductionThe long-term effect of angiotensin II receptor blockers (ARBs) on atrial fibrillation (AF) is unclear. In this study, we evaluated the change in the fibrillation cycle length (FCL) in patients under long-term ARB therapy for chronic AF.Methods and resultsThe study population consisted of 25 chronic AF patients who were prescribed the same medication for more than 6 years and in whom specific ECG recording for FCL evaluation could be performed before and after the 6-year observation period. The patients were divided into 2 groups: those with and without ARB (ARB group and non-ARB group and n=15 and 10, respectively). FCL was calculated by the spectral analysis of the fibrillation waves in the surface ECG. There was no significant difference in the clinical characteristics between the 2 groups. In the ARB group, the mean FCL was prolonged from 154±20ms to 187±37ms (p=0.005), whereas it remained unchanged in the non-ARB group (150±12ms vs. 149±10ms). In the comparison between patients with and those without FCL prolongation (>30ms; n=6 and 19, respectively), a significant difference was observed only in those prescribed ARBs.ConclusionIn cases of chronic AF, FCL might be prolonged under long-term ARB treatment

Evaluation of the impact of atrial fibrillation on rehospitalization events in heart failure patients in recent years

SummaryBackgroundAlthough we have previously reported that the presence of paroxysmal atrial fibrillation (AF) is an independent risk factor for rehospitalization in patients with congestive heart failure (CHF) in a population from 1996 to 2002, the impact of AF configuration as a risk factor in a more recent population remains to be clarified.Methods and results319 patients with CHF admitted to our institute in 2006–2007 were retrospectively evaluated. The patients were divided into 3 groups in accordance with their basic cardiac rhythm, i.e. sinus rhythm (n=210), chronic AF (n=68), and paroxysmal AF (n=41). During the follow-up period of 19±17months, there was no significant difference in mortality or rehospitalization events among the 3 groups (p=0.542). In the multivariate analysis, no administration of β-blockers was the only independent risk factor for rehospitalization due to CHF exacerbation.ConclusionsThe clinical impact of AF configuration as a risk factor of rehospitalization due to CHF exacerbation was considered to be decreased in recent years

Prophylactic catheter ablation for ventricular tachycardia reduces morbidity and mortality in patients with implantable cardioverter–defibrillator devices

Abstract Background Although the use of implantable cardioverter–defibrillator/cardiac resynchronization therapy device with a defibrillator (ICD/CRT‐D) is the principal therapy for patients with life‐threatening ventricular tachyarrhythmias/ventricular fibrillation (VT/VF), prophylactic VT ablation may reduce arrhythmic episodes and mortality in patients with an ICD/CRT‐D. In this retrospective study, the prognoses among patient groups with different results of attempted VT ablation were compared. Methods The study population consisted of 151 consecutive patients with an ICD/CRT‐D and structural heart disease. The mean age was 64±9 years, and 63 of the 151 patients were women. Of the 151 patients, 117 cases underwent catheter ablation procedure for elimination of monomorphic VT. The 151 patients were divided into 3 groups based on the results of the ablation or whether ablation was attempted, i.e., success, failure, and not‐attempted groups (n=87, 30, and 34, respectively). The event rate of VT/VF and total mortality were compared among the 3 groups. Results During a follow‐up period of 31±22 months, VT/VF episodes and death occurred in 45 (30%) and 16 (11%) patients, respectively. When comparing the 3 groups, the rates of VT/VF episodes and death were significantly lower in the success group than in the failure and not‐attempted groups (16.1%, 46.7%, 50.0%, p=0.0001 and 6.9%, 20.0%, 11.8%, p=0.0213, respectively). Conclusion In patients with an ICD/CRT‐D implant for VT/VF, prophylactic ablation of monomorphic VT may reduce morbidity and mortality

Subacute pneumothorax contralateral to the venous access site associated with atrial lead perforation in a patient who was receiving corticosteroid therapy

Pneumothorax contralateral to the venous access site due to the right atrial lead is an uncommon complication. Concomitant steroid use is known as a risk factor of pacemaker lead perforation. We report a rare case of subacute contralateral pneumothorax due to a screw-in atrial lead perforation that occurred after dual-chamber pacemaker implantation in a patient who was receiving steroid therapy. The pneumothorax disappeared, and no recurrence was observed during follow-up with close observation alone

Effect of nifekalant on life-threatening ventricular arrhythmias in patients with cardiopulmonary resuscitation or during the perioperative state

Background: Nifekalant is a unique class III anti-arrhythmic agent with a strong effect on prolonging the myocardial refractoriness, but its clinical effect is still unclear. In this study, we evaluated the effect of nifekalant on life-threatening ventricular arrhythmias and compared the clinical background between the effective and non-effective patients in order to clarify the clinical factors which may have an influence on the efficacy of nifekalant. Methods: The study population consisted of 47 consecutive patients who underwent nifekalant administration for life-threatening ventricular arrhythmias (VT/VF). Their clinical characteristics and ECG parameters were retrospectively compared between patients with and without an effective result with the nifekalant administration. Results: Nifekalant was effective for refractory VT/VF in 26/47 patients. There was no significant difference in the age, gender or left ventricular ejection fraction, but the incidence of ischemic heart disease was higher in the effective group (17/26) than non-effective group (9/21, p = 0.004). The incidence of in-hospital events was higher in the effective group than non-effective group (20/26 vs 10/21, p = 0.037). A significant prolongation in the QTc interval was observed in all patients and the degree of QTc prolongation was greater in the effective group than in the non-effective group (0.46 ± 0.04 vs 0.43 ± 0.02 sec1/2, p = 0.026). Conclusion: Nifekalant was effective in 55% of the patients for refractory VT/VF. It was considered that nifekalant was more effective for patients with ischemic heart disease, during the perioperative period or in those experiencing in-hospital events. The prolongation of the QTc interval might also be useful as an index for the efficacy of nifekelant administration