Satoru Sakuragi

Atrial Fibrillation in Patients With Brugada Syndrome : Relationships of Gene Mutation, Electrophysiology, and Clinical Backgrounds

OBJECTIVES The goal of our work was to examine the relationships of atrial fibrillation (AF) with genetic, clinical, and electrophysiological backgrounds in Brugada syndrome (BrS). BACKGROUND Atrial fibrillation is often observed in patients with BrS and indicates that electrical abnormality might exist in the atrium as well as in the ventricle. SCN5A, a gene encoding the cardiac sodium channel, has been reported to be causally related to BrS. However, little is known about the relationships of atrial arrhythmias with genetic, clinical, and electrophysiological backgrounds of BrS. METHODS Seventy-three BrS patients (49 +/- 12 years of age, men/women = 72/1) were studied. The existence of SCN5A mutation and clinical variables (syncopal episode, documented ventricular fibrillation [VF], and family history of sudden death) were compared with spontaneous AF episodes. Genetic and clinical variables were also compared with electrophysiologic (EP) parameters: atrial refractory period, interatrial conduction time (CT), repetitive atrial firing, and AF induction by atrial extra-stimulus testing. RESULTS Spontaneous AF occurred in 10 (13.7%) of the BrS patients and SCN5A mutation was detected in 15 patients. Spontaneous AF was associated with higher incidence of syncopal episodes (60.0% vs. 22.2%, p < 0.03) and documented VF (40.0% vs. 14.3%, p < 0.05). SCN5A mutation was associated with prolonged CT (p < 0.03) and AF induction (p < 0.05) in EP study, but not related to the spontaneous AF episode and other clinical variables. In patients with documented VF, higher incidence of spontaneous AF (30.8% vs. 10.0%, p < 0.05), AF induction (53.8% vs. 20.0%, p < 0.03), and prolonged CT was observed. CONCLUSIONS Spontaneous AF and VF are closely linked clinically and electrophysiologically in BrS patients. Patients with spontaneous AF have more severe clinical backgrounds in BrS. SCN5A mutation is associated with electrical abnormality but not disease severity.

Longer Repolarization in the Epicardium at the Right Ventricular Outflow Tract Causes Type 1 Electrocardiogram in Patients With Brugada Syndrome

OBJECTIVES We examined the relationship between repolarization abnormality and coved-type ST-segment elevation with terminal inverted T-wave (type 1 electrocardiogram [ECG]) in patients with Brugada syndrome (BrS). BACKGROUND Recent experimental studies have suggested that accentuation of the right ventricular action potential (AP) notch preferentially prolongs epicardial AP causing inversion of the T-wave. METHODS In 19 patients with BrS and 3 control subjects, activation-recovery intervals (ARIs) and repolarization times (RTs) in the epicardium and endocardium were directly examined with the use of local unipolar electrograms at the right ventricular outflow tract. Surface ECG, ARI, and RT were examined before and after administration of pilsicainide. RESULTS Type 1 ECG was observed in 10 of the 19 BrS patients before the administration of pilsicainide and in all of the 19 patients after the administration of pilsicainide. We found that ARI and RT in the epicardium were shorter than those in the endocardium in all 9 BrS patients without type 1 ECG under baseline conditions and in all control subjects regardless of pilsicainide administration. However, longer epicardial ARI than endocardial ARI was observed in 8 of the 10 BrS patients manifesting type 1 ECG under baseline conditions and in all of the BrS patients after the administration of pilsicainide. Also, epicardial RT was longer than endocardial RT in all patients manifesting type 1 ECG regardless of pilsicainide administration. CONCLUSIONS Our data provide support for the hypothesis that the negative T-wave associated with type 1 BrS ECG is due to a preferential prolongation of the epicardial AP secondary to accentuation of the AP notch in the region of the right ventricular outflow tract.

Differences in right and left ventricular remodeling after transcatheter closure of atrial septal defect among adults

Objectives: To evaluate acute cardiac remodeling after transcatheter closure of atrial septal defect (ASD) in adult patients. Background: In adult patients with ASD, longer periods of cardiac adaptation should be expected after the procedure due to long‐standing RV volume overload and subsequent changes in the pulmonary vasculature. There are limited reports about this remodeling in adult patients. Methods: We prospectively enrolled 17 adults (mean age 58.4 ± 17.3 years) who underwent successful transcatheter closure of their ASDs from August 2005 to July 2006. We performed routine transthoracic echocardiographic studies, including LV and RV myocardial performance indices, or Tei indices, and plasma brain natriuretic peptide (BNP) sampling before closure of the ASD, and 1 day, 1 month, and 3 months after closure. Results: We found (1) LV end diastolic diameter increased, and RVEDD decreased markedly after the closure; (2) differences existed in LV and RV adaptation. While LV Tei index improved soon after the procedure, RV Tei index worsened until 1 month after the procedure, then recovered by the 3 month follow‐up visit; and (3) BNP elevated 1 day after closure of the ASD and declined by the 1‐month follow‐up visit. Conclusion: “Shrinkage” of the RV and “expansion” of the LV occurred soon after the procedure, even in elderly patients. Device closure of ASDs caused rapid improvement of LV function, but RV function underwent transient deterioration, probably due to delayed changes in RV ventricular mass in the face of acute volume reduction in this aged cohort.

A case of takotsubo cardiomyopathy associated with epileptic seizure: reversible left ventricular wall motion abnormality and ST-segment elevation

A 59-year-old woman was admitted for consciousness disturbance. She had a history of endocranial operation for astrocytoma. Her electrocardiogram showed ST-segment elevation indicative of acute myocardial infarction. Emergency coronary angiography showed normal coronary arteries, whereas left ventriculography showed extensive severe hypokinesis in the anteroseptal and apical segments. Electroencephalography showed slow sharp wave activity from the left frontal lobe to the temporal lobe, and she was diagnosed as having status epilepticus. This is a rare case of takotsubo cardiomyopathy associated with epileptic seizure. Acute myocardial ischemia caused by impaired coronary microcirculation induced by abnormal catecholamine release is a possible cause of cardiac wall motion abnormality, as in our case.

Aortic stiffness is an independent determinant of B-type natriuretic peptide in patients with coronary artery disease.

Previous studies demonstrated that the B-type natriuretic peptide (BNP) level is high in some patients with coronary artery disease (CAD) despite a preserved left ventricular function, although the mechanism underlying this increase in patients with CAD has not been fully elucidated. Because aortic stiffness is greater in patients with CAD and increases with CAD severity, there is a possibility that an increased aortic stiffness in turn increases the elevation of the BNP level in patients with CAD. In this study, we measured BNP level and brachial-ankle pulse wave velocity (baPWV) in 134 patients with CAD, and evaluated the relationship between BNP and baPWV. The patients were classified on the basis of the quartiles of BNP level to identify the characteristics of patients with a high BNP level. baPWV was significantly greater in patients classified into the highest quartile of BNP level than in those classified into the other quartiles. Multivariate analysis demonstrated that baPWV and left ventricular ejection fraction independently correlated with BNP level. Logistic regression analysis demonstrated that the odds ratio for the highest quartile of BNP level increased with baPWV quartile. This association remained significant after adjustment for systolic and diastolic function. In conclusion, increased aortic stiffness possibly underlies the increase in the BNP level in patients with CAD.

Aortic Stiffness Is an Independent Predictor of Left Ventricular Function in Patients with Coronary Heart Disease

Although aortic stiffness plays an important role in patients with coronary artery disease (CAD), the influence of aortic stiffness on left ventricular systolic function has not yet been fully evaluated. In the present study, we measured brachial-ankle pulse wave velocity (baPWV), which is a new index of aortic stiffness, in patients with CAD (CAD group, n = 170, 67 ± 9 years old) and without CAD (non-CAD group, n = 81, 63 ± 8 years old), and evaluated the relationship between baPWV and left ventricular systolic function in patients with CAD. baPWV in the CAD group was significantly higher than that in the non-CAD group (1,794 ± 350 vs. 1,469 ± 292 cm/s, p < 0.05), although both systolic and diastolic blood pressure were comparable between the two groups. In the CAD group, the baPWV was higher in patients with three-vessel disease than that in patients with one-vessel disease (1,885 ± 542 vs. 1,720 ± 373 cm/s, p < 0.05). In the CAD group, multivariate analysis demonstrated that baPWV and pulse pressure independently correlated with left ventricular ejection fraction (LVEF). In conclusion, in patients with CAD, baPWV, which is a simple marker of aortic stiffness, increases with CAD severity and correlates with left ventricular systolic function independent of CAD severity.

Local delivery of single low-dose of C-type natriuretic peptide, an endogenous vascular modulator, inhibits neointimal hyperplasia in a balloon-injured rabbit iliac artery model

C-type natriuretic peptide (CNP) is an endogenous vascular modulator. In addition to vasodilation, CNP exerts multifunctions including anti-thrombus and anti-proliferation actions against vascular smooth muscle cells and myofibroblasts. Therefore, CNP is a potential therapeutic agent for the prevention of restenosis following angioplasty. The current study investigated whether local delivery of CNP, even at microgram levels about three orders of magnitude lower than doses (high milligram levels) used for systemic administration in the previous study, attenuates neointimal hyperplasia. The rabbit iliac artery was denuded, and then CNP (100 &mgr;g, n = 5) or control vehicle (n = 5) was administered locally over 20 min, via a local drug delivery catheter. During drug delivery, blood pressure was monitored with a high-fidelity micromanometer catheter. There was no significant decrease in arterial pressure immediately after the CNP administration. Four weeks after the treatment, computer-assisted morphometric analysis revealed significant reduction in the intimal area (CNP 0.44 ± 0.27 versus control 0.96 ± 0.20 mm2, p < 0.01), but no changes in the medial area (CNP 0.93 ± 0.23 versus control 0.79 ± 0.29 mm2, p = NS). This resulted in a significant decrease in the ratio of the intimal area to the medial area in CNP-treated vessels compared with control vessels (CNP 0.45 ± 0.26 versus control 1.40 ± 0.66, p < 0.05). Local delivery of a single low dose of CNP effectively inhibits neointimal hyperplasia with a minimal likelihood of compromising hemodynamics. Considering its multipotent actions and its role as an important regulator of the vascular system, this treatment may have a therapeutic advantage for clinical use.

Clinical features of and effects of angiotensin system antagonists on amiodarone-induced pulmonary toxicity

BACKGROUND Amiodarone (AMD) is a strong antiarrhythmic drug but has severe side effects such as pulmonary toxicity. There are no indicators or drugs that can prevent the development of amiodarone-induced pulmonary toxicity (AIPT). METHODS We collected data for 96 consecutive patients treated with AMD and analyzed clinical factors related to AIPT. In addition, we examined the effect of AMD and angiotensin II (Ang II) on human lung alveolar epithelial cells (AEC) and verified the protective efficacy of an Ang II type 1 receptor blocker (ARB) in vitro. RESULTS During a follow-up period of 33.8+/-34.6 months, AIPT developed in 11 patients (11.5%). There were no differences in the dose of AMD, left ventricular ejection fraction, serum KL-6 and %DLCO level before starting AMD between patients with and those without AIPT. However, repeated episodes of congestive heart failure (CHF) were observed more frequently in patients with AIPT than in patients without AIPT (81.8% vs. 41.2%, P<0.011). In vitro examination, AMD progressively increased apoptosis of AEC and Ang II enhanced this effect of AMD (P<0.001). However, ARB inhibited the enhancement by Ang II of the AMD-induced apoptosis effect (P<0.001). Furthermore, patients with AIPT were administrated a lower dose of angiotensin system antagonists than were those without AIPT (P<0.05). CONCLUSIONS The results indicate that Ang II induced by CHF increases the risk of AMD-induced pulmonary toxicity. An angiotensin-converting enzyme inhibitor or ARB should be given at a sufficient dose during AMD treatment.

Effects of combined treatment with angiotensin II type 1 receptor blocker and statin on stent restenosis.

Angiotensin II type I receptor blocker (ARB) or statin has been reported to be effective in preventing stent restenosis, but little is known about the combined effect on stent restenosis. The objective of this study was to determine the effect of combination therapy with ARB and statin on restenosis rate after coronary stenting and on proliferation and migration of and reactive oxygen species (ROS) production by human coronary artery smooth muscle cells (SMCs) in vitro. Clinical data were collected from 330 consecutive patients who underwent coronary stenting for de novo lesions. Six months after stenting, quantitative coronary angiography was performed. Combined therapy with the ARB and statin significantly inhibited stent restenosis (P < 0.05) compared with the effect of the ARB or statin alone. In an in vitro study, platelet-derived growth factor (PDGF)-induced proliferation was significantly inhibited by combined treatment with CV11974, an ARB, and simvastatin (P < 0.01), but the inhibitory effect was not significantly greater than that of simvastatin alone. Migration of human coronary artery SMCs was significantly inhibited by the ARB + statin compared with the effect of the ARB or statin alone (P < 0.01). PDGF-induced production of ROS was also inhibited significantly by the ARB + statin compared with the effect of the ARB or statin alone (P < 0.01). These results indicate that inhibitory effects of combined therapy on PDGF-induced migration of and ROS production by SMCs play an important role in reduction of restenosis rate. Combined treatment with ARB and statin after stenting is useful for preventing stent restenosis.

Effect of remote ischemia or nicorandil on myocardial injury following percutaneous coronary intervention in patients with stable coronary artery disease: A randomized controlled trial

BACKGROUND The effect of remote ischemic preconditioning (RIPC) and nicorandil on periprocedural myocardial injury (pMI) in patients with planned percutaneous coronary intervention (PCI) remains controversial. The aim of this randomized trial was to evaluate the effect of RIPC or nicorandil on pMI following PCI in patients with stable coronary artery disease (CAD) compared with a control group. METHODS Patients with stable CAD who planned to undergo PCI were assigned to a 1:1:1 ratio to control, RIPC, or intravenous nicorandil (6mg/h). Automated RIPC was performed by a device, which performs intermittent arm ischemia through three cycles of 5min of inflation and 5min of deflation of a pressure cuff. The primary outcome was the incidence of pMI, determined by an elevation in high-sensitive troponin T or creatine kinase myocardial band at 12 or 24h after PCI. The secondary outcomes were ischemic events during PCI and adverse clinical events at 8months after PCI. RESULTS A total of 391 patients were enrolled. The incidence of pMI following PCI was not significantly different between the control group (48.9%) and RIPC group (39.5%; p=0.14), or between the control group and nicorandil group (40.3%; p=0.17). There were no significant differences in ischemic events during PCI or adverse clinical events within 8months after PCI among the three groups. CONCLUSIONS This study demonstrated moderate reductions in biomarker release and pMI by RIPC or intravenous nicorandil prior to the PCI consistently, but may have failed to achieve statistical significance because the study was underpowered.