Miyako Igarashi

PPAR-γ Activator Pioglitazone Prevents Age-Related Atrial Fibrillation Susceptibility by Improving Antioxidant Capacity and Reducing Apoptosis in a Rat Model

PPAR‐γ Activator as Upstream Therapy for Atrial Fibrillation in Rat. Introduction: The in vivo role of peroxisome proliferator‐activated receptor (PPAR)‐γ, an essential transcriptional mediator of lipid and glucose metabolism, in atrial fibrillation (AF) remains to be fully elucidated. We investigated the effects of pioglitazone, a PPAR‐γ activator, in an in vivo AF rat model.

Concomitant obstructive sleep apnea increases the recurrence of atrial fibrillation following radiofrequency catheter ablation of atrial fibrillation: clinical impact of continuous positive airway pressure therapy.

BACKGROUND Recent studies have suggested an emerging link between obstructive sleep apnea (OSA) and atrial fibrillation (AF). Patients with OSA are less likely to remain in sinus rhythm after radiofrequency catheter ablation of AF. OBJECTIVE To evaluate the efficacy of appropriate treatment with continuous positive airway pressure (CPAP) on recurrences of AF after ablation. METHODS This study prospectively included 153 patients (128 men; 60 ± 9 years) who underwent extensive encircling pulmonary vein isolation for drug refractory AF. The standard overnight polysomnographic evaluation was performed 1 week after ablation, and the total duration and the number of central or obstructive sleep apnea or hypopnea episodes were examined. RESULTS Of 153 patients, 116 patients were identified as having OSA. Data regarding the use of CPAP and recurrences of AF were obtained in 82 patients. The remaining 34 patients with OSA were defined as the no-CPAP group. Polysomnography revealed no sleep-disordered breathing in 37 patients. During a mean follow-up period of 18.8 ± 10.3 months, 51 (33%) patients experienced AF recurrences after ablation. A Cox regression analysis revealed that the left atrial volume (hazard ratio [HR] 1.11; 95% confidence interval [CI] 1.01-1.23; P<.05), concomitant OSA (HR 2.61; 95% CI 1.12-6.09; P<.05), and usage of CPAP therapy (HR 0.41; 95% CI 0.22-0.76; P<.01) were associated with AF recurrences during the follow-up period. CONCLUSIONS Patients with untreated OSA have a higher recurrence of AF after ablation. Appropriate treatment with CPAP in patients with OSA is associated with a lower recurrence of AF.

Complex Left Atrial Appendage Morphology and Left Atrial Appendage Thrombus Formation in Patients With Atrial Fibrillation

Background—In patients with atrial fibrillation (AF), most thrombus forms in the left atrial appendage (LAA). However, the relation of LAA morphology with LAA thrombus is unknown. Methods and Results—We prospectively enrolled 633 consecutive patients who were candidates for catheter ablation for symptomatic drug-resistant AF. Transesophageal echocardiography (TEE) was performed to assess LAA thrombus. LAA structure was assessed by 3-dimensional TEE. LAA orifice area, depth, volume, and number of lobes were measured on reconstructed 3-dimensional images. Clinical characteristics and echocardiographic measures were compared to determine variables predicting LAA thrombus. Excluded were 69 (10.9%) patients who met the exclusion criteria. Finally, this study comprised 564 patients, of whom LAA thrombus was observed in 36 (6.4%) patients. Multivariate analysis revealed CHADS2 (Congestive heart failure, Hypertension Age>75, Diabetes mellitus and prior Stroke or transient ischemic attack) score (P=0.002), left ventricular ejection fraction (P=0.01), degree of spontaneous echo contrast (P=0.02), left atrial volume (P=0.02), and number of LAA lobes (P<0.001) to be independently associated with thrombus formation. Most patients with LAA thrombus (32/34, 94.4%) had ≥3 LAA lobes, whereas LAA thrombus was observed in only 2 (0.7%) of 296 patients with 1 or 2 lobes. LAA volume significantly decreased in patients maintaining sinus rhythm after catheter ablation (P=0.0009). Number of LAA lobes did not change in any patient. Conclusions—Complex LAA morphology characterized by an increased number of LAA lobes was associated with the presence of LAA thrombus independently of clinical risk and blood stasis. This study suggests that LAA morphology might be a congenital risk factor for LAA thrombus formation in patients with AF.

Left Atrial Stiffness Relates to Left Ventricular Diastolic Dysfunction and Recurrence After Pulmonary Vein Isolation for Atrial Fibrillation

Left Atrial Stiffness and Atrial Fibrillation. Introduction: An increased left atrial (LA) stiffness reflects the structural remodeling and deterioration of the LA function. This study was designed to estimate LA stiffness by measuring a combination of the strain and LA pressure in patients undergoing pulmonary vein isolation (PVI) of atrial fibrillation (AF) and to evaluate the influence of the LA stiffness on the cardiac function, serum markers, and recurrence of AF after PVI.

Concomitant chronic kidney disease increases the recurrence of atrial fibrillation after catheter ablation of atrial fibrillation: A mid-term follow-up

BACKGROUND Chronic kidney disease (CKD) is often associated with atrial fibrillation (AF). However, its impact on the results of radiofrequency catheter ablation for AF has not been fully examined. OBJECTIVE The purpose of this study was to clarify the relationship between CKD and postcatheter ablation AF recurrence. METHODS The study included 221 patients with AF who underwent successful catheter ablation. The prevalence and characteristics of AF recurrences were determined. CKD was defined as an estimated glomerular filtration rate <60 mL/min/1.73 m(2). RESULTS After mean follow-up of 31.9 ± 7.6 months, 87 (39%) patients had AF recurrences. Multivariate Cox regression analysis revealed that CKD (hazard ratio [HR] 2.089, 95% confidence interval [CI] 1.292-3.378, P <.01) and left atrial volume (HR 1.009, 95% CI 1.002-1.017, P <.05) were independent predictors of AF recurrences. Among the 221 patients, 54 (24.4%) had CKD. Patients with CKD had a higher incidence of AF recurrences (57.4%) compared to the non-CKD patients (33.5%, P <.01). Compared with patients without CKD, patients with CKD were older (64 ± 11 years vs 58 ± 10 years, P <.001) and had a higher prevalence of hypertension (72% vs 53%, P <.05), larger left atrial volume (74.7 ± 29.4 mL vs 62.0 ± 26.0 mL, P <.01), and higher plasma B-type natriuretic peptide levels (129.6 ± 209.3 pg/mL vs 68.8 ± 91.0 pg/mL, P <.01). CONCLUSION The presence of CKD increased the risk of AF recurrences after catheter ablation. Multifactorial physiologic factors due to CKD may account for the higher prevalence of recurrent AF in patients with CKD than in those without.

Prevalence and characteristics of asymptomatic excessive transmural injury after radiofrequency catheter ablation of atrial fibrillation.

BACKGROUND Even with a low energy setting, radiofrequency energy applications on the left atrial (LA) posterior wall may cause excessive transmural injury (ETI) during catheter ablation of atrial fibrillation (AF). OBJECTIVE The purpose of this study was to clarify the prevalence and characteristics of ETI. METHODS This study included 104 patients with AF who underwent extensive encircling pulmonary vein isolation (EEPVI) followed by an endoscopic examination (≤48 hours after EEPVI). EEPVI was performed under conscious sedation, and the ablation settings at the LA posterior wall were a maximum energy of 20 to 25 W and duration of ≤30 seconds. The ETI was defined as any injury that resulted from EEPVI, including esophageal damage or periesophageal nerve injury. RESULTS ETIs were found in 10 (9.6%) patients and were all asymptomatic; esophageal damage in 4 patients and periesophageal nerve injury in the remaining 6. All patients with ETI were below normal weight (body mass index [BMI] < 24.9 kg/m(2)), and consisted of 17% of those below normal weight. The procedural parameters such as the type of energy source, total duration of energy applications to the LA posterior wall, additional LA linear ablation, and biochemical markers were not related to the ETI. In the logistic multiadjusted model, the BMI (per 1 kg/m(2)) was the only independent predictor of ETI (odds ratio = 0.76; 95% confidence interval = 0.59 to 0.97, P < .05). CONCLUSION Asymptomatic ETIs were not rare even with a low energy setting in patients below normal weight. Tailored energy settings based on the patients BMI may be required when performing EEPVI.

Systematic Treatment Approach to Ventricular Tachycardia in Cardiac Sarcoidosis

Background—Fatal arrhythmia is commonly observed in cardiac sarcoidosis, but clinical effects of a systematic treatment approach are still uncertain. This study sought to describe both clinical and electrophysiological characteristics and outcomes of systematic treatment approach to ventricular tachycardia (VT) associated with cardiac sarcoidosis. Methods and Results—We enrolled 37 consecutive patients (11 men; age, 56±11 years) with a diagnosis of sustained VT associated with cardiac sarcoidosis. Clinical effects of a systematic treatment approach including medical therapy (both steroid and antiarrhythmic agents), in association with radiofrequency catheter ablation, were evaluated. All patients received antiarrhythmic agents, and 34 received steroid therapy. During a 39-month follow-up, 23 (62%) patients were free from any VT episodes with medical therapy. Multivariable Cox regression analyses revealed that the absence of gallium-67 myocardial uptake was an independent predictor for VT recurrence (hazard ratio, 7.51; 95% confidence interval, 1.65–34.26; P<0.01). Fourteen patients who experienced VT recurrences even while on drug therapy underwent radiofrequency catheter ablation. Electrophysiological study revealed that the mechanisms of VTs could be classified into 2 subgroups: Purkinje-related or scar-related VT. The QRS duration of VT was narrower in Purkinje-related than in scar-related VTs (157±23 versus 183±22 ms; P<0.05). After a 33-month follow-up subsequent to the radiofrequency catheter ablation, 6 of 14 patients experienced VT recurrence. The number of VTs sustained during electrophysiological study was higher in the patients with VT recurrence than in those without (3.7±1.4 versus 1.9±0.8; P<0.01). Conclusions—A systematic treatment approach to cardiac sarcoidosis with VT successfully suppressed VT recurrences in the majority of patients studied.

High Washout Rate of Iodine-123-Metaiodobenzylguanidine Imaging Predicts the Outcome of Catheter Ablation of Atrial Fibrillation

123 I‐MIBG and Ablation for Atrial Fibrillation. Introduction: Excessive sympathetic nervous activity may contribute to atrial fibrillation (AF) recurrences after ablation, but its precise role remains controversial. The goals of this study were to assess the effects of AF on the iodine‐123‐metaiodobenzylguanidine (123I‐MIBG) findings and to elucidate its impact on the procedural outcome in patients undergoing a first‐time catheter ablation to treat AF.

Anemia and reduced kidney function as risk factors for new onset of atrial fibrillation (from the Ibaraki prefectural health study).

Chronic kidney disease (CKD) is a potential independent risk factor for atrial fibrillation (AF). It remains unclear whether anemia is synergistically associated with increased risk of AF onset in subjects with CKD. We evaluated the association of kidney function, hemoglobin (Hb), and their combination with new-onset AF in a population-based cohort study. We conducted a 15-year prospective cohort study of 132,250 Japanese subjects aged 40 to 79 years who participated in annual health checkups from 1993. Kaplan-Meier survival analysis was used to compare freedom from new-onset AF between groups classified by estimated glomerular filtration rate grade, Hb grade, and their combination. Cox proportional hazard model analysis was used to estimate hazard ratios (HRs) for new-onset AF. During a 13.8-year mean follow-up period, 1,232 (0.93%) subjects with new-onset AF were identified. Lower estimated glomerular filtration rate and lower Hb grades were significantly associated with a higher incidence of new-onset AF. Multivariate HRs and 95% confidence intervals (CIs) of new-onset AF were 1.38 (1.21 to 1.56) for mild CKD group, 2.56 (2.09 to 3.13) for CKD group, and 1.50 (1.24 to 1.83) for anemia group. Borderline Hb level was not significantly associated with increased risk for new-onset AF (HR 1.07, CI 0.91 to 1.25, p = 0.4284). In the model with interaction term between CKD and anemia, the risk was significantly higher (p = 0.0343 for the interaction) than that predicted by each factor independently. In conclusion, decreased kidney function and lower Hb level are associated with increased risk for new-onset AF, especially when both are present.

Effect of eplerenone on maintenance of sinus rhythm after catheter ablation in patients with long-standing persistent atrial fibrillation.

Several studies have demonstrated a relation between the rennin-angiotensin-aldosterone system and atrial fibrillation (AF), but there are no reports on the effect of eplerenone, a selective aldosterone blocker, on the prevention of AF recurrence after radiofrequency catheter ablation (RFCA). The aim of this study was to evaluate the effects of eplerenone on clinical outcomes after RFCA in patients with long-standing persistent AF. A total of 161 consecutive patients with long-standing persistent AF (sustained AF duration 1 to 20 years, mean 3.4 ± 3.8) who underwent RFCA were investigated. Eplerenone was used in 55 patients and not used in the remaining 106 patients. Other conventional pharmacologic agents, including angiotensin-converting enzyme inhibitors or angiotensin type 1 receptor blockers, were used equally in the 2 groups. After 24 months of follow-up, 47% of the patients were free from AF recurrence. The rate of freedom from AF recurrence was significantly greater in the eplerenone group (60%) than in the noneplerenone group (40%) (p = 0.011). By univariate analysis, the duration of sustained AF (p <0.001), left atrial diameter (p = 0.010), left atrial volume index (p = 0.017), and early AF recurrence (p <0.001) were significantly associated with AF recurrence, and the use of eplerenone was associated with maintenance of sinus rhythm after RFCA (p = 0.022). Multivariate Cox regression analysis showed that longer duration of sustained AF (>3 years) (p <0.001) and early AF recurrence (p <0.001) were significantly associated with AF recurrence, and only eplerenone therapy significantly improved maintenance of sinus rhythm (p = 0.017). In conclusion, eplerenone significantly improved maintenance of sinus rhythm after RFCA in patients with long-standing persistent AF.