Daisuke Horiuchi

Comparison of lesion formation between contact force-guided and non-guided circumferential pulmonary vein isolation: A prospective, randomized study

BACKGROUND Contact force (CF) monitoring could be useful in accomplishing circumferential pulmonary vein (PV) isolation (CPVI) for atrial fibrillation (AF). OBJECTIVE The purpose of this study was to compare procedure parameters and outcomes between CF-guided and non-guided CPVI. METHODS Thirty-eight consecutive AF patients (mean age 60 ± 11 years, 28 paroxysmal AF) undergoing CPVI were randomized to non-CF-guided (n = 19) and CF-guided (n = 19) groups. CPVI was performed with the ThermoCool SmartTouch catheter in both groups. The end-point was bidirectional block between the left atrium (LA) and PV. In the CF group, CF was kept between 10 and 20 g during CPVI, whereas in the non-CF group, all CF information was blanked. Radiofrequency energy at 30 W in the anterior and 25 W in the posterior LA wall was applied for 20-25 seconds at each point. RESULTS CPVI was successfully accomplished without any major complications in both groups. Mean CF in the non-CF and CF groups were 5.9 ± 4.5 g and 11.1 ± 4.3 g, respectively, for left-side CPVI, and 9.8 ± 6.6 g and 12.1 ± 4.8 g, respectively, for right-side CPVI (both P <.001). The procedure and fluoroscopy times for CPVI in the non-CF and CF groups were 96 ± 39 minutes and 59 ± 16 minutes, respectively (P <.001), and 22 ± 63 seconds and 9 ± 20 seconds (P = NS), respectively. Total number of residual conduction gaps was 6.3 ± 3.0 in the non-CF group and 2.8 ± 1.9 in the CF group (P <.001). During 6-month follow-up, 84.2% of patients in the non-CF group and 94.7% in the CF group were free from any atrial tachyarrhythmias (P = .34). CONCLUSION CF-guided CPVI is effective in reducing procedure time and additional touch-up ablation and may improve long-term outcome.

Efficacy and safety of low-dose pioglitazone after primary coronary angioplasty with the use of bare metal stent in patients with acute myocardial infarction and with type 2 diabetes mellitus or impaired glucose tolerance.

Thiazolidinediones (TZDs) have beneficial effects on markers of cardiovascular risk in patients with type 2 diabetes mellitus (DM). This study aimed to investigate the efficacy and safety of low-dose pioglitazone (15 mg per day) in patients with acute myocardial infarction (AMI) and type 2 DM or impaired glucose tolerance (IGT) treated with coronary angioplasty using bare metal stent (BMS). In 56 patients, pioglitazone was orally administered for 6 months after stenting (pioglitazone group). The incidence of in-stent restenosis (ISR) and left ventricular end-diastolic volume index (LVEDVI) at acute phase and 6 months after stenting in these patients were retrospectively compared with those in the other 37 patients (control group) treated without pioglitazone. No adverse events including death, emergency bypass surgery, and reinfarction, occurred in any patients in the hospital. There was no congestive heart failure (CHF) during a follow-up period in the pioglitazone group. At 6 months after stenting, the overall angiographic ISR rate was significantly lower in the pioglitazone group than in the control group (28.6% vs 48.6%, P = 0.049). In patients with hemoglobin A1c (HbA1c) <7.0% at follow-up, the ISR rate was also significantly lower in the pioglitazone group than in controls (21.3% vs 44.8%, P = 0.03). Delta-LVEDVI (defined as follow-up LVEDVI minus acute LVEDVI) was similar between the pioglitazone group and control group (0.13 vs 5.16 ml/m2, P = 0.482). Low-dose pioglitazone seems to have a potential to reduce ISR and does not adversely affect LV remodeling after AMI treated with coronary angioplasty using BMS in patients with type 2 DM or IGT.

Reduced residual conduction gaps and favourable outcome in contact force-guided circumferential pulmonary vein isolation

Abstract Aims Although contact force (CF)-guided circumferential pulmonary vein isolation (CPVI) for paroxysmal atrial fibrillation (PAF) is useful, AF recurrence at long-term follow-up still remains to be resolved. The purpose of this study was to assess safety and efficacy of CF-guided CPVI and to compare residual conduction gaps during CPVI and long-term outcome between the conventional (non-CF-guided) and the CF-guided CPVI. Methods and results We studied the 50 consecutive PAF patients undergoing CPVI by a ThermoCool EZ Steer catheter (conventional group, mean age 61 ± 10 years) and the other 50 consecutive PAF patients by a ThermoCool SmartTouch catheter (CF group, 65 ± 11 years). The procedure parameters and residual conduction gaps during CPVI, and long-term outcome for 12 months were compared between the two groups. Circumferential pulmonary vein isolation was successfully accomplished without any major complications in both groups. Total procedure and total fluoroscopy times were both significantly shorter in the CF group than in the conventional group (160 ± 30 vs. 245 ± 61 min, P < 0.001, and 17 ± 8 vs. 54 ± 27 min, P < 0.001, respectively). Total number of residual conduction gaps was significantly less in the CF group than in the conventional group (2.7 ± 1.7 vs. 6.3 ± 2.7, P < 0.05). The AF recurrence-free rates after CPVI during 12-month follow-up were 96% (48/50) in the CF group and 82% (41/50) in the conventional group (P = 0.02 by log rank test). Multivariate Cox regression analysis further supported this finding. Conclusion Contact force-guided CPVI is safe and more effective in reducing not only the procedure time but also the AF recurrence than the conventional CPVI, possibly due to reduced residual conduction gaps during CPVI procedure.

High Correlation of Estimated Local Conduction Velocity with Natural Logarithm of Bipolar Electrogram Amplitude in the Reentry Circuit of Atrial Flutter

Low conduction velocity (CV) in the area showing low electrogram amplitude (EA) is characteristic of reentry circuit of atypical atrial flutter (AFL). The quantitative relationship between CV and EA remains unclear. We characterized AFL reentry circuit in the right atrium (RA), focusing on the relationship between local CV and bipolar EA on the circuit.

Validation of Accuracy of Three‐Dimensional Left Atrial CartoSound™ and CT Image Integration: Influence of Respiratory Phase and Cardiac Cycle

CartoSound™ (CS) module is useful in integrating 3‐dimensional (3D) left atrial (LA) image with CT image. Integration method, however, has not been established. We reported the accuracy of LA electroanatomical (EA) and CT image integration by registering LA roof (LAR) and posterior wall (LAPW).

CHA2DS2-VASc and HAS-BLED scores and activated partial thromboplastin time for prediction of high plasma concentration of dabigatran at trough

INTRODUCTION Although dabigatran, an oral direct thrombin inhibitor, does not require routine monitoring, high plasma concentration of dabigatran (PDC) at trough level is shown to be a high risk for bleeding in patients with nonvalvular atrial fibrillation (NVAF). As dabigatran prolongs the activated partial thromboplastin time (APTT), we examined relationships of PDC at trough with APTT and clinical features to identify patients at high risk for major bleeding during dabigatran treatment. MATERIALS AND METHODS In the consecutive 48 patients with NVAF taking dabigatran at a daily dose of 220mg (n=32) or 300mg (n=16), we measured PDC using HEMOCLOT Thrombin Inhibitor assay and APTT ratio to control before (trough) and 2hours after taking dabigatran. RESULTS PDC was positively correlated with APTT ratio (R(2)=0.64, p<0.0001). Using this regression equation and values of median trough PDC 116 (46.7-269) ng/mL observed in patients with major bleeding in the RE-LY trial, we calculated the expected value of APTT ratio corresponding to the 10th percentile of trough PDC (46.7). It was 1.20. There was a significant increase in trough PDC with increasing CHA2DS2-VASc score (p=0.01) and with increasing HAS-BLED score (p=0.01), especially in CHA2DS2-VASc score ≥4 and in HAS-BLED score ≥3, respectively. The highest trough PDC was obtained in patient group with CHA2DS2-VASc score ≥4, HAS-BLED score ≥3, or creatinine clearance ≤80, each combined with trough APTT ratio ≥1.20. CONCLUSIONS This study provides an important clinical implication for identifying patients at high risk for major bleeding during dabigatran treatment in clinical practice.

Potential roles of the wearable cardioverter-defibrillator in acute phase care of patients at high risk of sudden cardiac death: A single-center Japanese experience

BACKGROUND The wearable cardioverter-defibrillator (WCD) has been expected to play a role as an effective bridge therapy to implantable cardioverter-defibrillator (ICD) implantation in patients at high risk of ventricular tachyarrhythmias (VA). Although WCD has been available since April 2014 in Japan, its usefulness remains unclear. METHODS AND RESULTS During the early period after hospitalization, patients at high risk of VA after excluding some elderly patients were prescribed WCD. The consecutive 50 patients with WCD use (median age 56 years, 38 for secondary prevention) were studied. We analyzed clinical efficacy and safety of WCD, and examined its potential roles. Of the 50 patients, 38 used WCD only during hospitalization. During WCD use [median 16 (IQR 8-33) days], all patients wore WCD for 98% of a day regardless of in or out-of-hospital use. Sustained VA was detected in 4 patients (8%; for primary prevention in 1) with 7 episodes, and 6 of 7 episodes required shock therapy. Of the 6 shock therapies, 4 were for sustained ventricular tachycardia with the median rate of 236beats/min (IQR 203-250), and the other 2 for ventricular fibrillation. Subsequently, only 27 patients (54%) of all underwent ICD implantation following the WCD use, because of reduced risk of VA after optimal pharmacological therapy or improvement in the left ventricular function. CONCLUSIONS The WCD use for the acute phase care of patients at high risk of VA can be safe and effective, and may be useful for evaluating indication of ICD implantation.

Effect of pilsicainide on dominant frequency in the right and left atria and pulmonary veins during atrial fibrillation: association with its atrial fibrillation terminating effect.

Dominant frequency reflects the peak cycle length of atrial fibrillation. In 34 patients with atrial fibrillation, bipolar electrograms were recorded from multiple atrial sites and pulmonary veins and the effect of pilsicainide, class Ic antiarrhythmic drug, on dominant frequency was examined. At baseline, mean dominant frequencies (Hz) in the right and left atria, coronary sinus and right and left superior pulmonary veins were 5.87 +/- 0.76, 6.08 +/- 0.60, 5.65 +/- 0.95, 6.12 +/- 0.88 and 6.59 +/- 0.89, respectively (P < 0.05, left superior pulmonary vein vs right atrium and coronary sinus). After pilsicainide (1.0 mg/kg/5 min), dominant frequency decreased at all sites in all patients. Atrial fibrillation was terminated at 5.9 +/- 2.2 min in 16 patients (Group A) with a decrease in the average of mean dominant frequencies at all sites from 5.80 +/- 0.72 to 3.57 +/- 0.63 Hz, was converted to atrial flutter at 7.3 +/- 1.4 min in 5 (Group B) with a decrease in the average dominant frequency from 5.83 +/- 0.48 to 3.08 +/- 0.19 Hz, and was not terminated in the other 13 (Group C) despite the average dominant frequency decrease from 6.59 +/- 0.76 to 4.42 +/- 0.52 Hz. In 14 of the 21 Groups A and B patients (67%), mean dominant frequencies at all recording sites were < 4.0 after pilsicainide, while they were < 4.0 in 1 of the 13 Group C patients (8%, P < 0.01). In conclusion, the degree of dominant frequency decrease by pilsicainide is closely related to its atrial fibrillation terminating effect: When dominant frequency in the atria decreases to < 4.0 Hz, atrial fibrillation is terminated with 93% positive and 63% negative predictive values.

Usefulness of combined CARTO electroanatomical mapping and manifest entrainment in ablating adenosine triphosphate-sensitive atrial tachycardia originating from the atrioventricular node vicinity

By using a noncontact mapping system, adenosine triphosphate (ATP)‐sensitive atrial tachycardia (ATP‐AT) originating from the atrioventricular (AV) node vicinity was successfully ablated at the entrance to the slow conduction zone indicated by the manifest entrainment technique. We aimed to prospectively validate the efficacy of the combination of CARTO electroanatomical mapping and manifest entrainment in ablating this ATP‐AT.

Long-term Efficacy of Combination Therapy with Anti-arrhythmic Agents and Pravastatin in Patients with Paroxysmal Atrial Fibrillation

Objective: To investigate the long‐term effects of combination therapy with antiarrhythmic agents and pravastatin (10 mg/day) in maintaining sinus rhythm in patients with paroxysmal atrial fibrillation (AF) and hyperlipidemia.