Shingo Sasaki

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.

Mechanism of ST elevation and ventricular arrhythmias in an experimental Brugada syndrome model.

Background—Although phase 2 reentry is said to be responsible for initiation of ventricular tachycardia (VT) in Brugada syndrome, information about the activation sequence during VT is limited. Methods and Results—We developed an experimental Brugada syndrome model using a canine isolated right ventricular preparation cross-circulated with arterial blood of a supporter dog and examined the VT mechanism. Two plaque electrodes (35×30 mm) containing 96 bipolar electrodes were attached to the endocardium and epicardium. Saddleback and coved types of ST elevation in transmural ECG were induced by pilsicainide, a pure sodium channel blocker, and pinacidil, a KATP channel opener. Eighteen polymorphic VT episodes were recorded in 9 of the 12 preparations associated with ST elevation. Fourteen episodes spontaneously developed in 5 preparations after an extrasystole during basic drive pacing. Analysis of local recovery times revealed increased dispersion especially in epicardium, and the extrasystole originated from a site with a short recovery time, suggesting that phase 2 reentry was its mechanism. The other 4 VTs in 4 preparations were induced by premature stimulation. Analysis of the activation sequences during VT revealed reentry between epicardium and endocardium or reentry around an arc of a functional block confined to epicardium or endocardium with bystander activation of the other. Conclusions—Electrical heterogeneity in the recovery phase was induced in this experimental Brugada syndrome model, which can be a substrate for the development of phase 2 reentry and the subsequent reentry around an arc of the functional block, resulting in sustained VT.

Nucleotide changes in the translated region of SCN5A from Japanese patients with Brugada syndrome and control subjects.

The mutations of the SCN5A gene have been implicated to play a pathogenetic role in Brugada syndrome, which causes ventricular fibrillation. To determine the Brugada-associated mutations in Japanese patients, facilitate pre-symptomatic diagnosis, and allow genotype-phenotype studies, we screened unrelated patients with Brugada syndrome for mutations. DNAs from 6 Japanese patients were obtained and the sequence in the translated region of SCN5A was determined. We could not find the mutations reported previously, but found 17 sites of nucleotide change, consisting of 7 synonymous and 10 non-synonymous nucleotide changes in our patients. Among them, two non-synonymous nucleotide changes (G1663A and G5227A) are specific to our patients and these changes were not found in 53 healthy controls. In 4 patients out of 6, no specific nucleotide change for Brugada syndrome could be detected. Our findings demonstrating no patient-specific change in the translated region of the SCN5A gene among two thirds of the small number of patients examined here imply that another gene other than the SCN5A may be associated with this disease, supporting previous investigations in Japan and other countries.

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.

Increased serum anandamide level at ruptured plaque site in patients with acute myocardial infarction

Inflammation caused by activated macrophages and T lymphocytes may trigger plaque rapture in acute coronary syndrome (ACS). Anandamide and 2‐arachidonylglycerol (2‐AG) are macrophage‐derived signal lipids and may be involved in the pathogenesis of ACS, but no clinical relevant data have been reported. In 43 acute myocardial infarction (AMI) patients (66 ± 2 years), blood samples were obtained from the aortic root and the infarct‐related coronary artery (IRA) using a PercuSurge system during primary percutaneous coronary intervention (PCI). In six patients with stable effort angina (SEA) (56 ± 6 years), blood samples were obtained from the site of stenosis during elective PCI. In 25 of the 43 AMI patients, anandamide was detected in the serum. Serum anandamide level was 35 ± 20 pmol/mL in the aorta and was significantly increased to 401 ± 134 pmol/mL in the IRA (P < 0.01). 2‐AG was undetectable in most of the patients. In patients with SEA, neither anandamide nor 2‐AG was detected in the serum at the plaque site. In AMI patients with anandamide detected, left ventricular ejection fraction at 2 weeks after PCI was increased by 3.7 ± 2.1% compared with that at the acute phase, while it was decreased by 3.0 ± 1.8% in those without anandamide detected (P < 0.05). The serum anandamide level at the culprit lesion was elevated compared with the systemic level in a significant number of AMI patients, indicating the synthesis of anandamide at the IRA. Anandamide was suggested to be derived from ruptured plaque and may exert beneficial effects in humans.

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.

Impact of telmisartan on coronary stenting in patients with acute myocardial infarction compared with enalapril

OBJECTIVE To determine whether telmisartan reduces in-stent restenosis (ISR) after coronary angioplasty using bare metal stent (BMS) in patients with acute myocardial infarction (AMI) compared with an angiotensin converting enzyme (ACE) inhibitor. BACKGROUND The efficacy of inhibition of renin-angiotensin-aldosterone system in patients with AMI has been established, and the prescription of ACE inhibitor is recommended as class I indication for all AMI patients, whereas that of angiotensin II receptor blocker (ARB) as class IIa. Telmisartan is a unique ARB since it has a peroxisome proliferator-activated receptor (PPAR) gamma activating effect which is known to reduce neointimal tissue proliferation after coronary stenting. METHODS In 64 patients, telmisartan (20-40 mg per day) was orally administered for 6 months after stenting (telmisartan group). The incidence of ISR after stenting in these patients was retrospectively compared with those in the other 60 patients administrated enalapril (2.5-5 mg per day) (enalapril group). RESULTS There were no adverse events such as death, re-infarction and emergency bypass surgery in telmisartan group during a follow-up period for 6 months. The ISR rate was lower in telmisartan group (18.8%) than in enalapril group (33.3%) (p=0.06). However, percent diameter stenosis (%DS) at follow-up in telmisartan group was significantly smaller than in enalapril group (26.7+/-18.6% vs 38.0+/-23.9%, p=0.004). Late lumen loss was also significantly smaller in telmisartan group than in enalapril group (0.97+/-0.48 mm vs 1.19+/-0.68 mm, p=0.039). CONCLUSIONS Telmisartan not only is tolerable in patients with AMI but has a potential to reduce neointimal tissue proliferation after AMI treated with coronary angioplasty using BMS compared with enalapril.

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).

V-H-A Pattern as a criterion for the differential diagnosis of atypical AV nodal reentrant tachycardia from AV reciprocating tachycardia.

Background: During ventricular extrastimulation, His bundle potential (H) following ventricular (V) and followed by atrial potentials (A), i.e., V‐H‐A, is observed in the His bundle electrogram when ventriculo‐atrial (VA) conduction occurs via the normal conduction system. We examined the diagnostic value of V‐H‐A for atypical form of atrioventricular nodal reentrant tachycardia (AVNRT), which showed the earliest atrial activation site at the posterior paraseptal region during the tachycardia.