Angiotensin II does not influence expression of sarcoplasmic reticulum Ca2 + ATPase in atrial myocytes

Introduction. The sarcoplasmic reticulum Ca2+ ATPase (SERCA) is essential for the regulation of the intracellular calcium level in cardiomyocytes. Previous studies have found that angiotensin II (Ang II) decreased SERCA2 gene expression in ventricular myocytes. Alteration of SERCA activity is important in the mechanism of atrial fibrillation. The present study was undertaken to examine Ang II effects on atrial myocytes.

Materials and methods. An ~1.75-kb promoter region of SERCA2 gene was cloned with the pGL3 luciferase vector. The direct effects of Ang II on SERCA2 gene expression in HL-1 atrial myocytes were examined by promoter activity assay, followed by Western blot analysis for protein levels and quantitative real-time reverse transcription polymerase chain reaction for mRNA amounts.

Results. Ang II did not increase the promoter activity of the 1,754-bp promoter-receptor construct of the SERCA2 gene. The levels of SERCA2 protein and mRNA were also unchanged at different time points after Ang II treatment.

Conclusions. Although Ang II had prominent effects on SERCA2 in ventricular myocytes, it did not alter SERCA2 gene expression and protein levels in atrial myocytes. We provide a model for further investigation of the regulation of SERCA2 gene expression in atrial myocytes.

Clinical spectrum and long-term outcome of Ebstein's anomaly based on a 26-year experience in an Asian cohort

Ebstein's anomaly is a rare, congenital cardiac anomaly that may result in cyanosis, right heart failure, and tachyarrhythmia during the newborn stage or after adolescence. This study investigated the data of 77 patients diagnosed between 1980 and 2006 at a tertiary care center in Taiwan. Patients were grouped into either an early group or a late group. Survival declined rapidly within the newborn stage in the early group, but declined only during the third decade in the late group. Surgical results were poor (20% success rate) for neonatal systemic-to-pulmonary shunts in those cases with associated pulmonary atresia, but were satisfactory for other surgical modes. Supraventricular tachyarrhythmia occurred in 31 (41%) patients at a median age of 10 years and could be eliminated by radiofrequency ablation (81% success rate), though the recurrence rate was high (41%). In conclusion, other than those cases requiring shunts at the newborn stage, the long-term outcome was favorable.

Distinct functional defect of three novel Brugada syndrome related cardiac sodium channel mutations

The Brugada syndrome is characterized by ST segment elevation in the right precodial leads V1-V3 on surface ECG accompanied by episodes of ventricular fibrillation causing syncope or even sudden death. The molecular and cellular mechanisms that lead to Brugada syndrome are not yet completely understood. However, SCN5A is the most well known responsible gene that causes Brugada syndrome. Until now, more than a hundred mutations in SCN5A responsible for Brugada syndrome have been described. Functional studies of some of the mutations have been performed and show that a reduction of human cardiac sodium current accounts for the pathogenesis of Brugada syndrome. Here we reported three novel SCN5A mutations identified in patients with Brugada syndrome in Taiwan (p.I848fs, p.R965C, and p.1876insM). Their electrophysiological properties were altered by patch clamp analysis. The p.I848fs mutant generated no sodium current. The p.R965C and p.1876insM mutants produced channels with steady state inactivation shifted to a more negative potential (9.4 mV and 8.5 mV respectively), and slower recovery from inactivation. Besides, the steady state activation of p.1876insM was altered and was shifted to a more positive potential (7.69 mV). In conclusion, the SCN5A channel defect related to Brugada syndrome might be diverse but all resulted in a decrease of sodium current.

Joint effects of N-terminal pro-B-type-natriuretic peptide and C-reactive protein vs angiographic severity in predicting major adverse cardiovascular events and clinical restenosis after coronary angioplasty in patients with stable coronary artery disease

BACKGROUND

This study was designed to evaluate the joint effects of plasma C-reactive protein (CRP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) vs coronary angiographic severity on cardiovascular risk stratification.

METHODS AND RESULTS

A total of 345 patients with stable coronary artery disease (CAD) were recruited after successful percutaneous coronary intervention (PCI). Endpoints were major adverse cardiovascular events (MACE) and cumulative clinical restenosis rate after 18-36-month follow-up. Plasma NT-proBNP and CRP levels were among the strongest predictors of MACE. Adjusted hazard ratios of MACE according to combined biomarkers were 2.4 (p=0.05) for elevated CRP only, 5.22 (p<0.001) for elevated NT-proBNP only, and 7.04 (p<0.001) for elevation of both. The differential capacity using both plasma CRP and NT-proBNP in a receiver-operating-characteristics curve analysis (area under curve, AUC: 0.82) was significantly higher than using either biomarker alone or conventional risk factors (AUC: 0.67). Significant predictors of clinical restenosis were plasma NT-proBNP and the Gensini score. The combination of NT-proBNP and the Gensini score was the strongest predictor (AUC: 0.77) for clinical restenosis.

CONCLUSIONS

Plasma NT-proBNP, CRP, and the Gensini score are complementary in risk stratification. Combined use of these biomarkers has provided substantial extra information to conventional risk factors in stable CAD patients.

Molecular genetics of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. There is genetic predisposition for the development of AF. Recently, by linkage analysis, several loci have been mapped for monogenetic AF, including 11p15.5, 21q22, 17q, 7q35-36, 5p13, 6q14-16, and 10q22. Some of these loci encode for subunits of potassium channels (KCNQ1, KCNE2, KCNJ2, and KCNH2 genes), and the remaining are yet unidentified. All of the known mutations are associated with a gain of function of repolarization potassium currents, resulting in a shortening of action potential duration and atrial refractory period, which facilitate multiple re-entrant circuits in AF. In addition to familial AF, common AF often occurs in association with acquired diseases such as hypertension, valvular heart disease, and heart failure. By genetic association study, some genetic variants or polymorphisms related to the mechanism of AF have been found to be associated with common AF, including genes encoding for subunits of potassium or sodium channels, sarcolipin gene, renin-angiotensin system gene, connexin-40 gene, endothelial nitric oxide synthase gene, and interleukin-10 gene. These observations suggest that genes related to ionic channels, calcium handling protein, fibrosis, conduction and inflammation play important roles in the pathogenesis of common AF. The complete elucidation of genetic loci for common AF is still in its infancy. However, the availability of genomewide scans with hundreds or thousands of polymorphisms has made it possible. However, challenges and pitfalls exist in association studies, and consideration of particular features of study design is necessary before making definite conclusions from these studies.

Serum bilirubin is inversely associated with insulin resistance and metabolic syndrome among children and adolescents

OBJECTIVE

Bilirubin is a potent antioxidant and a cyroprotectant. Low serum bilirubin is associated with atherosclerosis. Little is known about its role in metabolic syndrome (MS) among children and adolescents.

METHODS

We examined 4723 children and adolescents aged 12-17 years with reliable measures of various serum hepatic profiles and metabolic risks from Health and Nutrition Examination Survey 1999-2004.

RESULTS

The results showed that the prevalence of the MS was from 6.6+/-1.2% in the lowest quartile to 2.1+/-1.9% in the highest quartile of the concentration of total bilirubin. The graded association remained significant after the adjustment of other co-variates. The odds ratios for the MS were around 0.29 (0.08-0.99) and 0.23 (0.08-0.65) for the upper two quartiles when using the lowest quartile as reference for the concentration of total bilirubin. The quartiles of the serum total bilirubin levels were inversely correlated with the homeostasis model assessment (HOMA-IR) and insulin while not associated with the serum C-reactive protein (CRP) levels.

CONCLUSIONS

The serum total bilirubin levels are inversely correlated with the prevalence of the MS. The mechanism of the association between MS and total bilirubin may be related to the insulin resistance status.

Functional studies on three novel HCNH2 mutations in Taiwan: identification of distinct mechanisms of channel defect and dissociation between glycosylation defect and assembly defect

Mutations of the KCNH2 with decreased channel activity lead to congenital long QT syndrome (LQTS). We studied the electrophysiological, glycosylation, trafficking and assembly properties of three novel KCNH2 mutations identified in Taiwanese patients with LQTS (p.N633D, p.R744fs, and p.P923fs). When expressed in HEK293T cells, p.N633D and p.R744fs HERG channels displayed no HERG current while p.P923fs HERG channel showed HERG current with significantly lower (34%) current density and faster inactivation kinetics. In Western blot analysis, pR744fs was the only one with glycosylation defect, which was in consistence with the confocal microscopic findings showing that p.R744fs-GFP was the only one with trafficking defect. However, p.R744fs-GFP differed from pR744fs in being fully glycosylated while p.R744fs fusion with GFP at the N-terminus revealed glycosylation defect. To access the assembly capacity of each mutant, co-immunoprecipitation was conducted. Wild type (WT), p.N633D, and p.P923fs HERG protein showed assembly ability while p.R744fs failed to assemble with neither WT nor itself. In conclusion, we identified three novel LQTS-related KCNH2 mutations and each had a distinct mechanism of channel defect. For p.R744fs mutant, adding GFP to the C-terminus rescued the glycosylation defect but the channel was still assembly defective indicating a dissociation between glycosylation and assembly defects.

Inverse correlation between heart rate recovery and metabolic risks in healthy children and adolescents: insight from the National Health and Nutrition Examination Survey 1999-2002

OBJECTIVE

Heart rate recovery (HRR) is a marker for survival. Little is known about the association between HRR and metabolic risks in healthy children or adolescents.

RESEARCH DESIGN AND METHODS

We examined 993 healthy children and adolescents aged 12-19 years with reliable measures of cardiovascular fitness from the National Health and Nutrition Examination Survey 1999-2002. HRR parameters 1-3 min after exercise were calculated from exercise test results. Anthropometric and metabolic risk factors as well as metabolic Z score were obtained.

RESULTS

The HRR parameters were inversely correlated with most of the metabolic risks, including waist circumference, systolic blood pressure (SBP), serum triglycerides, and serum C-reactive protein (CRP) levels, and were positively correlated with serum HDL levels. In multiple linear regression analysis, among the metabolic risks, waist circumference was the only parameter associated with HRR parameters (P = 0.038, 0.001, and 0.001 for 1-, 2-, and 3-min HRR, respectively) in boys. In girls, waist circumference (P = 0.001 and <0.001 for 2- and 3-min HRR, respectively), SBP (P = 0.029 for 1-min HRR), serum glucose (P = 0.021 for 2-min HRR), and serum CRP (P = 0.007 for 2-min HRR) levels were the most important determinants of HRR parameters. The adjusted 1-min HRR did not change across four quartiles of metabolic Z score, while the adjusted 3-min HRR decreased significantly with four quartiles of metabolic Z score.

CONCLUSIONS

Metabolic risks are inversely associated with HRR in healthy children and adolescents. Our finding suggests that there is a link between metabolic risks and autonomic nervous system functions in healthy young ages.

Provocation of masked left ventricular mechanical dyssynchrony by treadmill exercise in patients with systolic heart failure and narrow QRS complex

Tissue Doppler imaging-derived intra-left ventricular (LV) contractile dyssynchrony is an evolving prognostic parameter for patients with systolic heart failure (HF). However, whether and how exercise could abolish the synchronicity in HF patients with narrow QRS remains less studied. We evaluated a total of 33 HF patients with impaired LV ejection fraction (<50%), QRS duration < or =120 ms, and baseline dyssynchrony index (DI; standard deviation of electromechanical delay of 12 LV segments by tissue Doppler imaging) <33 ms. After a 6-minute treadmill exercise by modified Bruce protocol, the absolute time difference from QRS onset to peak systolic myocardial velocity of each segment was recorded immediately. With similar DI at rest and peak heart rates during exercise, 11 patients (33%) developed dyssynchrony (DI > or =33 ms) after exercise, and the others did not (44.7 +/- 8.0 vs 16.2 +/- 8.3 ms, p <0.001). Patients with dyssynchrony after exercise had greater baseline mitral early diastolic velocity/annular early diastolic velocity (E/Ea) (19 +/- 17 vs 10 +/- 5, p <0.026). Multivariate analysis revealed mitral E/Ea >10 at rest, indicating higher LV filling pressure, independently predicted the exercise-evoked dyssynchrony (odds ratio 18, 95% confidence interval 2 to 163, p <0.012). In conclusion, exercise uncovered masked LV dyssynchrony in 1/3 of systolic HF patients with narrow QRS, and exercise-provoked dyssynchrony could be predicted by mitral E/Ea >10 at rest.

Renin-angiotensin system gene polymorphisms and atrial fibrillation: a regression approach for the detection of gene-gene interactions in a large hospitalized population

OBJECTIVES

To test the association between renin-angiotensin system gene variants and atrial fibrillation (AF) using a regression approach.

METHODS

A total of 1,236 consecutive patients (227 with AF and 1,009 with normal sinus rhythm as controls) were recruited. Angiotensin-converting enzyme (ACE) gene I/D polymorphism; T174M, M235T, G-6A, A-20C, G-152A and G-217A polymorphisms of the angiotensinogen (AGT) gene, and A1166C polymorphism of the angiotensin II type I receptor (AT1R) gene were genotyped. We used a regression approach based on a generalized linear model to evaluate haplotype effects and to detect gene-gene interactions by incorporating interaction terms in the model.

RESULTS

In single-locus analyses, no locus was associated with AF. After adjustment for AF risk factors, we found significant differences in the global AGT gene haplotype profile (the global score statistic = 30.364, p = 0.001) and individual haplotype frequencies between AF patients and controls. Furthermore, significant 2-way gene-gene interactions between ACE I/D polymorphism and AGT gene haplotypes and between AT1R A1166C polymorphism and AGT gene haplotypes, and 3-way interaction between ACE I/D, AT1R A1166C and AGT gene haplotypes were detected.

CONCLUSIONS

These results are compatible with the concept of multilocus and multigene effects in determining the risk of complex diseases such as AF, which would be missed with conventional single-locus approaches.

Long-term outcome of twin atrioventricular node and supraventricular tachycardia in patients with right isomerism of the atrial appendage

BACKGROUND

Twin AV nodes and resulting supraventricular tachycardia (SVT) have been described in right atrial isomerism (RAI).

OBJECTIVE

We sought to analyze the long-term outcome of patients with RAI with a focus on rhythm disturbances.

METHODS

Retrospective study of 257 patients (152 male and 105 female, 1,171 patient-years) with RAI diagnosed between 1980 and 2005.

RESULTS

SVT in 68 patients (26%) occurred at various ages from the prenatal period to 15 years and was only significantly associated with balanced ventricles (P = .009). Cardioversion was achieved in by verapamil in 6 of 6 cases (100%), adenosine in 18 of 21 cases (88%) and propranolol in 10 of 12 cases (83%). Electrocardiographic evidence of twin AV nodes, as shown by 2 discrete non-pre-excited QRS complexes, was found in 28 of 44 (64%) patients with more than 2 electrocardiograms, and was more frequent in those with balanced ventricles rather than a dominant ventricle and would increase risk of SVT. Recurrence of SVT was documented in 27 (40%) patients 1 day to 4.5 years after the first episode. However, the occurrence or recurrence of SVT was not associated with increased all-cause or surgical mortality or sudden death. Successful catheter ablation of ventriculoatrial pathways with junctional ectopic tachycardia at radiofrequency energy delivery was obtained in 5 of 6 patients.

CONCLUSION

This study showed that twin AV nodes in RAI patients could be disclosed by serial electrocardiograms and that SVT, most likely a twin node tachycardia, was common and tended to recur but could be managed by ablation or medication.

Evolution of Left Atrial Systolic and Diastolic Functions in Different Stages of Hypertension: Distinct Effects of Blood Pressure Control

BACKGROUND

To evaluate the left atrial (LA) volume, and LA systolic (contractile) and diastolic (expansion) functions in different stages of hypertension with or without atrial fibrillation (AF), as well as the effects of good blood pressure control.

METHODS

A prospective observational study. Individuals including 22 normotensive controls, 23 patients with mild hypertension, 20 with severe hypertension, and 17 with hypertension and paroxysmal AF were recruited for paired echocardiography studies at baseline and 6 months after control of hypertension.

RESULTS

With increasing severity of hypertension, left ventricular (LV) diastolic function deteriorated with decreasing LV septal E'/A' and increasing E/E' ratios. LA expansion index was reduced in parallel. LA expansion index was correlated positively with LV E'/A' (r = 0.43, p = 0.022) and inversely with LV E/E' (r = 0.49, p = 0.009). Significant improvement of LV diastolic function and LA expansion index preceded the reduction of LA volume after blood pressure control. In patients with paroxysmal AF, LA volume reduction was more evident in patients receiving angiotensin-converting enzyme inhibitors or angiotensin II type 1 receptor blockers.

CONCLUSIONS

With progressive LV diastolic dysfunction in hypertension, there was a corresponding deterioration in LA diastolic function. Effective blood pressure control for 6 months improved LA diastolic function.

Morphologic and Topologic Characteristics of Coronary Venous System Delineated by Noninvasive Multidetector Computed Tomography in Chronic Systolic Heart Failure Patients

BACKGROUND

Variations of coronary venous system in a dilated, failing heart may well be unpredictable. Noninvasive preview of coronary veins before left ventricular (LV) lead implantation for cardiac resynchronization therapy would facilitate successful procedure in chronic systolic heart failure (SHF) patients.

METHODS AND RESULTS

Multidetector computed tomography (MDCT) of the heart was investigated in 23 consecutive patients of chronic SHF with LV ejection fraction < or = 40%. Morphologic and topologic characteristics of coronary venous system were studied, and compared with 23 age-matched controls. All coronary veins including coronary sinus, posterior interventricular vein (PIV), LV posterior vein, left margin vein (LMV), and anterior interventricular vein (AIV) were clearly visible in all 23 SHF patients and 23 normal controls. Total coronary venous length (ie, from PIV to AIV) was directly correlated with LV volume (r = 0.65, P < .001). The main lengthened venous segment was between LMV and AIV. Ostial diameters of all coronary venous tributaries were larger in SHF patients, but the angle of branching was similar. However, the secondary angle of the coronary sinus relative to superior vena cava axis was more acute (30 +/- 7 degrees) in SHF patients than that in normal (44 +/- 8 degrees, P < .001). Local aneurysm locating at LV posterolateral wall could detour relevant coronary vein tributaries to the outer border of the aneurysm, compress venous dimensions throughout the cardiac cycle, and cause acute angulation of venous tributaries.

CONCLUSIONS

Coronary venous system shown by MDCT in SHF patients with low LV ejection fraction manifested longer venous length between LMV and AIV, acute secondary CS angle, and usually topologically distorted by posterolateral LV aneurysms. A panoramic delineation of all coronary venous tributaries could help effective venous intervention.

Coexistence and exercise exacerbation of intraleft ventricular contractile dyssynchrony in hypertensive patients with diastolic heart failure

BACKGROUND

Patients with heart failure (HF) and a normal left ventricular ejection fraction usually present with diastolic dysfunction (DD). Whether intraleft ventricular contractile dyssynchrony (IVCD) coexists with DD and contributes to the clinical manifestations of HF remains unclear. The study investigated the IVCD at rest and after exercise in hypertensive patients with diastolic HF (DHF).

METHODS

Echocardiography was performed in 60 hypertensive patients with narrow QRS, left ventricular ejection fraction > or = 50%, and no active ischemia. Patients were grouped as having DD (mitral E/A < 1 plus E deceleration time > 200 milliseconds, or mitral annular early diastolic velocity < 8 cm/s; n = 26), DD plus HF symptoms/signs (DHF, n = 13), or as non-DD (n = 21).

RESULTS

At rest, the IVCD index (SD of 12 left ventricular segmental electromechanical delays) was greater in the DHF and DD groups than that in the non-DD group (52.2 +/- 10.7 and 39.1 +/- 23.6 vs 23.1 +/- 19.9 milliseconds; P < .05 for both comparisons). Six-minute treadmill exercise induced exacerbation of dyssynchrony in the DHF group (67.0 +/- 12.9 vs 52.2 +/- 10.7 milliseconds; P < .001). Multivariate analysis revealed that the combination of IVCD index > or = 35 milliseconds at rest and > or = 50 milliseconds after exercise was independently associated with DHF (odds ratio = 20, 95% CI = 2-199, P = .009). Postexercise IVCD index correlated positively with plasma N-terminal pro-brain natriuretic peptide (r = 0.37, P = .004).

CONCLUSIONS

Exercise would aggravate intraventricular dyssynchrony in hypertensive patients with DHF, implicating a potential contribution of systolic dyssynchrony to clinical manifestations.

Human C-reactive protein (CRP) gene 1059G>C polymorphism is associated with plasma CRP concentration in patients receiving coronary angiography

BACKGROUND/PURPOSE

Elevation of C-reactive protein (CRP) level is associated with increased risk of cardiovascular events. The 1059 G>C polymorphism in exon 2 of the CRP gene has been shown to affect plasma concentration of CRP. We want to elucidate the effect of this polymorphism on the development of coronary artery disease (CAD) among the Chinese population in Taiwan.

METHODS

We scrutinized 536 patients undergoing coronary angiography (365 patients with CAD and 171 controls with patent coronaries) and evaluated the association of CRP gene 1059 G>C polymorphism with CAD. Genotyping of the polymorphism was performed by polymerase chain reaction and MaeIII restriction enzyme digestion.

RESULTS

The CC genotype was associated with lower plasma CRP concentration (GG, 6.5+/-5.8; GC, 3.3+/-4.4; CC, 2.3+/-3.1 mg/L; p=0.02). Subjects with CAD or myocardial infarction (MI) had significantly higher plasma CRP concentration than that in controls (CAD vs. controls, 8.9+/-18.9 vs. 3.3+/-7.2 mg/L; p<0.001), while patients with MI showed higher CRP when compared to those with chronic stable angina (13.5+/-22.9 vs. 5.2+/-14.1 mg/L; p<0.001). However, this polymorphism was not associated with CAD in our population.

CONCLUSION

Our data suggest that human CRP gene 1059 G>C polymorphism is associated with plasma CRP concentration among Chinese in Taiwan receiving coronary angiography.

Increased expression of extracellular matrix proteins in rapid atrial pacing-induced atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is characterized by structural remodeling of the extracellular matrix (ECM) in cardiac atrium.

OBJECTIVE

The purpose of this study was to gain further insight into atrial ECM remodeling at the molecular level and to test whether altered expression of ECM proteins was associated with the disease.

METHODS

Sustained AF was induced in nine adult pigs after 3-4 weeks of continuous rapid atrial pacing at a rate of 600 bpm. Histologic studies and immunohistochemical stain were performed to identify the potential pathologic substrate underlying abnormalities in atrial tissues with sustained AF.

RESULTS

In the pathologic findings, the fraction of myocardial ECM (ECM%) was measured, with a significantly greater ECM% found in the AF group compared with the sham operated group (n = 6; i.e., pigs with normal sinus rhythm [SR]). A set of 9,182 genes was screened with cDNA microarray analysis. In AF animals, expression of 121 genes increased and 24 genes decreased by > or =1.75-fold compared with SR animals. Significant up-regulation of fibronectin-1 (4.9-fold), fibrillin-1 (3.1-fold), and fibromodulin (1.9-fold) in the fibrillating atria was confirmed by quantitative real-time reverse transcriptase-polymerase chain reaction. Western blot analysis revealed significantly increased atrial fibronectin-1, fibrillin-1, and fibromodulin in the AF group compared with the SR group (1.5-, 2.7-, and 2.1-fold, respectively). Immunohistochemical staining of AF tissue displayed increased accumulation of fibronectin-1 and fibrillin-1 in the atrial interstitial space.

CONCLUSION

Increased expression of ECM proteins in fibrillating atria supports the hypothesis that ECM metabolism contributes to the development of AF.

The effects of metabolic syndrome versus infectious burden on inflammation, severity of coronary atherosclerosis, and major adverse cardiovascular events

BACKGROUND

The clinical predictors of inflammation in atherosclerosis remain controversial. The objective of this study was to compare the associations of metabolic factors vs. infectious burden (IB) with inflammation, the severity of coronary atherosclerosis, and major adverse cardiovascular events (MACEs).

DESIGN, SETTING, AND PATIENTS

Coronary angiography with Gensini score was applied to assess the severity of coronary atherosclerosis in 568 patients with coronary artery disease. Metabolic syndrome (MS) score (0-5) was defined according to the modified criteria of National Cholesterol Education Program Adult Treatment Panel III. IB score (0-7) was defined as the number of seropositivities to several agents.

RESULTS

IB score was not associated with plasma C-reactive protein (CRP) concentration, Gensini score, or the risk of MACE. In contrast, MS score significantly correlated with both plasma CRP concentration and Gensini score (P < 0.001 for both). MS score and plasma CRP concentration were also significantly associated with the risk of MACE (hazard ratios 1.51, P < 0.001; and 1.90, P = 0.002, respectively).

CONCLUSION

Compared with IB, metabolic abnormalities have a more prominent association with the degree of inflammation, the severity of coronary atherosclerosis, and the risk of MACE in patients with coronary artery disease.

Amiodarone-related Pneumonitis

Amiodarone-related pneumonitis is a potentially limiting factor for amiodarone usage. However, it is believed that amiodarone-related pneumonitis is unlikely to occur during low-dose and short courses of therapy. We report three patients who received low-dose amiodarone, 200 mg/day, for an average of 6.6 months and who developed amiodarone-related pneumonitis. All patients were male with age of 75, 93 and 85, respectively, and had the habit of cigarette smoking. The initial presentation was dyspnea without symptoms and signs of heart failure. Their chest radiographs showed diffuse interstitial pneumonitis pattern and chest computed tomography scan also confirmed interstitial pneumonitis. Treatment included cessation of amiodarone and corticosteroid usage. All patients improved symptomatically by early detection and early treatment. This case report implies that old age and possible pre-existing pulmonary abnormalities caused by smoking could be associated with amiodarone-related pulmonary toxicity. Clinicians must remain alert to detect amiodarone-related pneumonitis even under low dosage and short duration of amiodarone usage. Immediate withdrawal of amiodarone and prompt steroid therapy will ensure full recovery.

Angiotensin II increases expression of alpha1C subunit of L-type calcium channel through a reactive oxygen species and cAMP response element-binding protein-dependent pathway in HL-1 myocytes

Angiotensin II (Ang II) is involved in the pathogenesis of atrial fibrillation (AF). L-type calcium channel (LCC) expression is altered in AF remodeling. We investigated whether Ang II modulates LCC current through transcriptional regulation, by using murine atrial HL-1 cells, which have a spontaneous calcium transient, and an in vivo rat model. Ang II increased LCC alpha1C subunit mRNA and protein levels and LCC current density, which resulted in an augmented calcium transient in atrial myocytes. An approximately 2-kb promoter region of LCC alpha1C subunit gene was cloned to the pGL3 luciferase vector. Ang II significantly increased promoter activity in a concentration- and time-dependent manner. Truncation and mutational analysis of the LCC alpha1C subunit gene promoter showed that cAMP response element (CRE) (-1853 to -1845) was an important cis element in Ang II-induced LCC alpha1C subunit gene expression. Transfection of dominant-negative CRE binding protein (CREB) (pCMV-CREBS133A) abolished the Ang II effect. Ang II (1 micromol/L, 2 hours) induced serine 133 phosphorylation of CREB and binding of CREB to CRE and increased LCC alpha1C subunit gene promoter activity through a protein kinase C/NADPH oxidase/reactive oxygen species pathway, which was blocked by the Ang II type 1 receptor blocker losartan and the antioxidant simvastatin. In the rat model, Ang II infusion increased LCC alpha1C subunit expression and serine 133 phosphorylation of CREB, which were attenuated by oral losartan and simvastatin. In summary, Ang II induced LCC alpha1C subunit expression via a protein kinase C-, reactive oxygen species-, and CREB-dependent pathway and was blocked by losartan and simvastatin.

Using multiple buddy wires to facilitate left ventricular lead advancement in cardiac resynchronization therapy

Left ventricular lead positioning is always the critical step in cardiac resynchronization therapy because of the complex anatomy of coronary sinus branches. We describe the case of a 46-year-old man with dilated cardiomyopathy and complete left bundle branch block presenting with heart failure. The placing of the left ventricular lead into the posterolateral branch was hampered by an angulated portion at the proximal branch even with the assistance of anchor wire technique and one to two additional parallel wires' support. The use of three buddy wires facilitated the advancement of the left ventricular lead.

The association of human connexin 40 genetic polymorphisms with atrial fibrillation

BACKGROUND

There is evidence showing that genetic factors contribute to the pathogenesis of atrial fibrillation (Af). We investigated the association between Af and polymorphisms of the connexin 40 (Cx40) gene, which is important in the electrical coupling between atrial myocytes.

METHODS

We performed an association study between two Cx40 single nucleotide polymorphisms (SNPs) (Cx40 -44 and +71 allele) and Af. We enrolled 173 patients with Af, and the control group consisted of 232 patients without Af. The luciferase assay was performed to evaluate the promoter activities of different Cx40 haplotypes in cultured atrial myocytes.

RESULTS

We found that the two SNPs were both significantly associated with Af. In pairwise linkage disequilibrium analysis, the two SNPs were completely linked (Cx40 -44G always associated with Cx40 +71A; Cx40 -44A associated with Cx40 +71G, P<0.001). In haplotype analysis, we demonstrated that the frequency of Cx40 (-44A,+71G) was significantly higher in the Af group than that in the control group (P<0.006, odds ratio=1.514, 95% confidence interval 1.13-2.04). We also performed genotype analysis using several genetic models, finding that the recessive model showed the lowest P value (P<0.004) and the largest odds ratio (2.53, 95% confidence interval 1.23-5.19). In promoter activity studies using luciferase as the reporter, Cx40 (-44A,+71G) had significantly lower promoter activity than that of the Cx40 (-44G,+71A) in atrial myocytes.

CONCLUSIONS

The two SNPs in the promoter region of the Cx40 gene were significantly associated with Af. The Cx40 (-44A +71G) haplotype was associated with a higher risk for Af. This haplotype also had significantly lower promoter activity in atrial myocytes.

Altered expression of FHL1, CARP, TSC-22 and P311 provide insights into complex transcriptional regulation in pacing-induced atrial fibrillation

Atrial fibrillation (AF) is the most common progressive disease in patients with cardiac arrhythmia. AF is accompanied by complex atrial remodeling and changes in gene expression, but only a limited number of transcriptional regulators have been identified. Using a low-density cDNA array, we identified 31 genes involved in transcriptional regulation, signal transduction or structural components, which were either significantly upregulated or downregulated in porcine atria with fibrillation (induced by rapid atrial pacing at a rate of 400-600 bpm for 4 weeks that was then maintained without pacing for 2 weeks). The genes for four and a half LIM domains protein-1 (FHL1), transforming growth factor-beta (TGF-beta)-stimulated clone 22 (TSC-22), and cardiac ankyrin repeat protein (CARP) were significantly upregulated, and chromosome 5 open reading frame gene 13 (P311) was downregulated in the fibrillating atria. FHL1 and CARP play important regulatory roles in cardiac remodeling by transcriptional regulation and myofilament assembly. Induced mRNA expression of both FHL1 and CARP was also observed when cardiac H9c2 cells were treated with an adrenergic agonist. Increasing TSC-22 and marked P311 deficiency could enhance the activity of TGF-beta signaling and the upregulated TGF-beta1 and -beta2 expressions were identified in the fibrillating atria. These results implicate that observed alterations of underlying molecular events were involved in the rapid-pacing induced AF, possibly via activation of the beta-adrenergic and TGF-beta signaling.

ATP-binding cassette transporter A1 gene I823M polymorphism affects plasma high-density lipoprotein cholesterol level and modifies the effect of low high-density lipoprotein cholesterol on the risk of coronary artery disease

BACKGROUND

The I823M polymorphism of the ATP-binding cassette transporter A1 (ABCA1) gene has been reported to affect plasma high-density lipoprotein cholesterol (HDL-C) level. Information about its relationship to coronary artery disease (CAD) is limited.

METHODS AND RESULTS

We included 205 patients with angiographically documented CAD and 201 controls from the general population. We found that I823M polymorphism was a significant source of variation of HDL-C (p = 0.024 after adjustment for age, sex, body mass index, smoking and alcohol drinking). Subjects with M823/M823 homozygotes (n = 103) had a higher HDL-C than those with I823/I823 or I823/M823 genotype (n = 98) (50.5 +/- 9.7 vs. 47.6 +/- 10.1 mg/dl, p = 0.039). I823M polymorphism was not a predictor of CAD in multivariate analysis (adjusted odds ratio = 1.5 [0.9-2.5], p = 0.145). However, it interacted with low HDL-C level to increase the risk of CAD. The odds ratio of CAD with M823 homozygosity was 5.3 (2.0-20.0) in patients with HDL-C < or = 35 mg/dl, but was only 1.0 (0.5-2.0) in those with HDL > 40 mg/dl (p = 0.039 for interaction).

CONCLUSIONS

M823 variant of the ABCA1 gene was associated with a higher HDL-C. Furthermore, I823M polymorphism interacted with low-HDL-C on the risk of CAD. It served as a marker to identify high-risk patients for CAD in subjects with low-HDL-C.

Downregulation of angiotensin converting enzyme II is associated with pacing-induced sustained atrial fibrillation

Atrial fibrillation (AF), the most common cardiac arrhythmia, is frequently accompanied by atrial interstitial fibrosis. Angiotensin II (Ang II) dependent signaling pathways have been implicated in interstitial fibrosis during the development of AF. However, Ang II could be further degraded by angiotensin converting enzyme II (ACE2). We examined expression of ACE2 in the fibrillating atria of pigs and its involvement in fibrotic pathogenesis during AF. Nine adult pigs underwent continuous rapid atrial pacing to induce sustained AF and six pigs were sham controls (i.e., sinus rhythm; SR). In the histological examinations, extensive accumulation of extracellular matrix in the interstitial space of the atria, as evidenced by Masson's trichrome stain, were found in fibrillating atria. The relative amount of collagen type I in the atria with AF was significantly increased as compared with that in the SR. Local ACE activity in the fibrillating atria was also markedly higher than that in the SR subjects. ACE2 gene and protein expression in the AF subjects were significantly decreased compared with those in the SR subjects, whereas expression of mitogen-activated/ERK kinase 1/2 (MEK1/2), extracellular signal-regulated protein kinase 2 (ERK2), and activated ERK2 were significantly greater in the AF subjects. We propose that decreasing ACE2 expression during AF may affect the Ang II-dependent signaling pathway. In addition, our results suggest that atrial fibrosis in AF may be induced by antagonistic regulation between ACE and ACE2 expression.

Renin-angiotensin system gene polymorphisms and coronary artery disease in a large angiographic cohort: detection of high order gene-gene interaction

There have been many reports regarding the association between renin-angiotensin system (RAS) gene polymorphisms and coronary artery disease (CAD) or acute myocardial infarction (AMI), but the results are inconsistent. In the present study, we used several new approaches with multilocus data to reappraise this issue in a large and relatively homogeneous Taiwanese population. A total of 1254 consecutive patients who underwent cardiac catheterization (735 with documented coronary artery disease and 519 without) between 1996 and 2003 were recruited. Angiotensin-converting enzyme gene insertion/deletion (I/D) polymorphism; T174M, M235T, G-6A, A-20C, G-152A and G-217A polymorphisms of the angiotensinogen gene; and A1166C polymorphism of the angiotensin II type I receptor gene were genotyped. In single-locus analyses, no locus was associated with CAD, history of AMI and three-vessel CAD, either with or without adjustment for conventional CAD risk factors. For multilocus analyses, we recreated a balanced population, with the controls individually matched to the cases regarding the conventional CAD risk factors. We found that the angiotensinogen gene haplotype profile was significantly different between the cases and controls (chi2=31.6, P=0.030) in haplotype analyses. Furthermore, significant three-locus (G-217A, M235T and I/D) gene-gene interactions were detected by multifactor-dimensionality reduction method (highest cross-validation consistency 10.0, lowest prediction error 40.56%, P=0.017) and many even higher order gene-gene interactions by multilocus genotype disequilibrium tests (16 genotype disequilibria exclusively found in the controls, all of which included at least two genes among AGT, ACE and AT1R genes). Our study is the first to demonstrate epistatic, high-order, gene-gene interactions between RAS gene polymorphisms and CAD. These results are compatible with the concept of multilocus and multi-gene effects in complex diseases that would be missed with conventional approaches.

Measuring Heart Rate Variability with Wavelet Thresholds and Energy Components in Healthy Subjects and Patients with Congestive Heart Failure

BACKGROUND

Analysis of wavelet thresholds and energy components can be used to differentiate patients with congestive heart failure (CHF) from healthy subjects and to demonstrate the improvement of heart rate variability after treatment with beta-blockers in the patient group.

METHODS

Nine patients with CHF without concurrent beta-blocker therapy and 15 healthy volunteers were recruited and received 24-hour Holter recording. Wavelet thresholds and energy components were calculated. The patients with CHF were then treated with atenolol for 3 months. Another Holter recording was repeated and associated wavelet parameters were estimated.

RESULTS

Wavelet thresholds were statistically higher in normal subjects than those derived from patients with CHF (62.40 +/- 20.65 vs. 16.90 +/- 9.72, p < 0.001). The difference was still significant after control of heart rate and the total number of heart beats (74.85 +/- 22.68 vs. 32.51 +/- 18.73, p < 0.001). The energy component of HRV in the finest wavelet domain was also significantly higher in the normal subjects (243.01 +/- 237.69 x 10(-6) vs. 40.65 +/- 39.65 x 10(-6), p = 0.001). These two measures increased after treatment with beta-blockers in the patients with CHF, but not to the extent of those of normal subjects.

CONCLUSION

Analysis of wavelet thresholds and energy components has provided robust and accurate measurements for background HRV.

Septal pacing preserving better left ventricular mechanical performance and contractile synchronism than apical pacing in patients implanted with an atrioventricular sequential dual chamber pacemaker

BACKGROUND

Permanent pacing is the treatment for chronotropically incompetent hearts. However, the right ventricular (RV) apical pacing-induced asynchrony, even maintaining the atrioventricular (AV) sequential activation, has depressed left ventricular contractility. Whether RV septal pacing would less compromise the electromechanical performance of the left ventricle and the chronotropic effect on myocardial contractility, is unknown.

METHODS

We prospectively studied 42 patients without structural heart diseases and with symptomatic bradycardia. There were 10 patients receiving atrial pacing (AAI) pacemakers, 18 patients having AV sequential pacing at RV apex (DDDapx) and 14 patients being AV sequentially paced at septum (DDDspt). Echocardiography was performed before and within 72 h after the pacemaker implantation. The ventricular mechanical performance and asynchrony was compared in conditions of programmed rates of 60, 80 and 100/min.

RESULTS

Myocardial performance index was significantly better in DDDspt than in DDDapx patients (p=0.003). With faster programmed rate, the QRS/RR increased (p<0.05) in DDDapx patients with more inter- and intraventricular asynchrony, implicating the disadvantage of prolonged depolarization time. The DDDspt group demonstrated comparable parameters of diastolic function to AAI patients and preserved mechanical performance during accelerated pacing.

CONCLUSIONS

RV septal pacing showed the advantages of shorter depolarization time, less ventricular contractile asynchrony, better mechanical performance and preserved chronotropic response on myocardial contractility in comparison with apical pacing.

A novel mutation (Arg169Gln) of the cardiac ryanodine receptor gene causing exercise-induced bidirectional ventricular tachycardia

An 18-year-old woman presented with exercise induced sudden collapse. Series of cardiac work up revealed no structural cardiac abnormalities. Bidirectional ventricular tachycardia occurred during a treadmill exercise test. Under the impression of catecholaminergic polymorphic ventricular tachycardia, we screened the cardiac ryanodine receptor gene for mutation. We identified a novel heterozygous mutation at the 169th amino acid (Arg169Gln). This amino acid is highly conserved among many species and this mutation was not present in 50 normal control subjects. This patient was treated with a beta-block with good response.

Successful radiofrequency catheter ablation of idiopathic ventricular fibrillation presented as recurrent syncope and diagnosed by an implanted loop recorder

As a palliative therapy, an implantable cardioverter-defibrillator (ICD) could not prevent the occurrence of ventricular tachycardia or fibrillation (VT, VF), but only suppress it by overdrive pacing or direct current shocks. Recurrent VT or VF followed by frequent ICD shocks might thus put patients in a painful disaster. We presented a case of recurrent syncope diagnosed as recurrent VF by an implanted loop recorder (ILR). The VF was eliminated by radiofrequency catheter ablation (RFCA) of triggering ventricular premature complexes (VPCs).

Immediate impairment of left ventricular mechanical performance and force–frequency relation by rate-responsive dual-chamber, but not atrial pacing: Implications from intraventricular isovolumic relaxation flow

BACKGROUND

Despite the maintenance of atrioventricular (AV) synchrony, the detrimental effect of left ventricular asynchronization on mechanical performance and intraventricular flow by nonphysiologic right ventricular apical pacing in dual-chamber pacing, with and without rate adaptation, is not clear.

METHOD

Twenty-seven consecutive patients receiving permanent pacemakers for symptomatic bradyarrhythmias (18 with DDD and 9 with AAI mode pacemakers) were evaluated with standard and tissue Doppler echocardiography before and 24 h after pacemaker implantation. The rate-response effect of pacing was studied by programmed rate with increments of 20, from 60 to 100/min.

RESULTS

Color M-mode echocardiography demonstrated that much more DDD patients developed new biphasic intraventricular flow during isovolumic relaxation period than AAI patients (13/18 versus 0/9, P<0.001). In DDD patients, the ventricular relaxation represented by mitral annulus velocity in early diastole significantly attenuated (before vs. after DDDR, 8.5+/-2.8 vs. 5.2+/-1.2 cm/s, P<0.05), and also the mitral flow propagation velocity (33+/-11 vs. 25+/-5 cm/s, P<0.01). The myocardial performance index increased after DDD (0.70+/-0.15 vs. 0.79+/-0.24, P<0.05) but not after AAI (0.61+/-0.1 vs. 0.59+/-0.08, P=NS). For both pacing groups, the accelerated pacing rate prolonged the isovolumic relaxation time and shortened the diastole period (P<0.001). However, only DDD patients had a decreased mitral flow propagation velocity (P=0.026) and an attenuated force-frequency relation in programmed rate acceleration.

CONCLUSION

Despite the AV synchrony, right ventricular apical pacing immediately attenuates the left ventricular contraction and relaxation performance, which deteriorated further and suppressed the physiologically positive force-frequency relation after accelerated pacing rate.

Erratum to: Denaturing high-performance liquid chromatography screening of the long QT syndrome-related cardiac sodium and potassium channel genes and identification of novel mutations and single nucleotide polymorphisms

The name Fon-Jou Hsieh was inadvertently omitted from the list of authors. The name should be added as the third author of the article.

Proximal common pathway in the circuit of atrioventricular nodal reentrant tachycardia

Whether atrium tissue is involved in the reentrant circuit of atrioventricular nodal reentrant tachycardia (AVNRT) has been debated for decades. Animal models, clinical electrophysiological studies, surgery and catheter ablation have all documented that the perinodal tissue forms part of the tachycardia circuit. However, the occasional clinical finding of AVNRT with ventriculoatrial block suggests the presence of a proximal common pathway. We describe a 43-year-old woman who developed recurrent AVNRT with new onset of complete ventriculoatrial block after an attempted radiofrequency ablation at the posterior septal area. This case demonstrates the anatomical existence of a proximal common pathway and the topological location of such a pathway for typical AVNRT. This case also demonstrates the isolated nature of the AVNRT circuit and the delicate nature of the responsible reentrant substrate.

EFFICACY AND ANTI-INFLAMMATION ACTIVITY OF A SELECTIVE PHOSPHODIESTERASE-4 INHIBITOR CILOMILAST IN TREATMENT OF COPD

BACKGROUND

Large-scale clinical trials have demonstrated that patients with atrial fibrillation (AF), when treated with a rhythm-control strategy, are still at risk for embolic events. We hypothesized that left atrial (LA) dysfunction persisted even after successful maintenance of sinus rhythm for > 3 months.

METHODS

A total of 93 patients with AF and satisfactory rhythm control for > 3 months were included. Satisfactory rhythm control was defined as being free of AF based on patient-reported symptoms, monthly ECG follow-up, and ambulatory Holter ECG if needed. Among the 93 patients, 25 patients had sustained AF that was terminated by electrical or pharmacologic cardioversion, while 68 patients had paroxysmal AF under good medical control. Clinical data were obtained, and transthoracic and transesophageal echocardiography were performed after satisfactory rhythm control for > 3 months.

RESULTS

Among the 93 patients, 34 patients (37%) had LA dysfunction, defined as LA appendage (LAA) peak emptying velocity < 40 cm/s or spontaneous echo contrast and/or thrombus in the LA or LAA. When compared to the other 59 patients without LA dysfunction, they had larger LA dimension (40 +/- 6 mm vs 36 +/- 8 mm [+/- SD], p = 0.018) but did not differ significantly regarding the left ventricular (LV) chamber size, LV ejection fraction, mitral or tricuspid inflow, and ratio of the amplitude of the waves created by early diastolic filling and atrial contraction. We also analyzed the relationship between LA function and clinical risk factors for stroke, including hypertension, diabetes mellitus, coronary artery disease, age > 65 years, and prior cerebral vascular accident. LA dysfunction was found in 10 of 17 patients (59%) with three or more risk factors. The odds ratio for having LA dysfunction was 3.1 (p = 0.04; 95% confidence interval, 1.1 to 9.1) when compared with patients with less than three risk factors.

CONCLUSIONS

LA dysfunction was present in more than one third of AF patients after satisfactory rhythm control for > 3 months. Patients with higher burden (three or more) of clinical risk factors were more likely to have impaired LA function.

Denaturing high-performance liquid chromatography screening of the long QT syndrome-related cardiac sodium and potassium channel genes and identification of novel mutations and single nucleotide polymorphisms

Mutations in cardiac potassium and sodium channel genes are responsible for several hereditary cardiac arrhythmia syndromes. We established a denaturing high-performance liquid chromatography (DHPLC) protocol for rapid mutation screening of these genes, and reported mutations and variations identified by this method. We included 28 patients with Brugada syndrome, 4 with congenital long QT syndrome (LQTS), 11 with drug-induced LQTS, 4 with idiopathic ventricular fibrillation, and 50 normal volunteers. Polymerase chain reactions were performed to amplify the entire coding region of these genes. DHPLC was used to screen for heteroduplexes then DNA sequencing was performed. With this method, we identified the mutation(s) in all four patients with congenital LQTS (KCNQ1 A341V, KCNH2 N633D, KCNH2 2768Cdel and KCNE1 K70 N Y81C double mutations). We also identified the SCN5A A551T mutation in 1 of the 28 patients with Brugada syndrome. All the above-mentioned mutations were novel except KCNQ1 A341V. No mutations were identified in patients with drug-induced LQTS or idiopathic ventricular fibrillation. In total, 25 single nucleotide polymorphisms were identified, 10 of which were novel. In conclusion, DHPLC is a sensitive and rapid method for detection of cardiac sodium and potassium channel gene mutations.

Identification of good responders to rhythm control of paroxysmal and persistent atrial fibrillation by transthoracic and transesophageal echocardiography

BACKGROUND

Identification of good responders to rhythm control in the management of atrial fibrillation (AF) is worthwhile in terms of increasing hemodynamic benefit and decreasing the likelihood of unstable anticoagulation even after the Atrial Fibrillation Follow-Up Investigation of Rhythm Management.

METHODS

We tested the hypothesis that atrial substrate determines the risk of recurrence on rhythm control both in patients with paroxysmal AF (PAF) and in those with persistent or sustained AF (> or =1 week, SAF). There were 90 consecutive patients (mean age 63 +/- 12 years, 67 males and 23 females) with previous PAF (n = 66) or SAF (n = 24). They were maintained in sinus rhythm successfully for at least 1 month after conversion and then studied by transthoracic and transesophageal echocardiography. All of the patients were followed regularly by determination of symptoms, 12-lead ECG and intermittent Holter recording to determine recurrence of AF after echocardiographic study.

RESULTS

After 9.1 +/- 3.8 (range 3-12) months of follow-up, 23 of the 90 (26%) patients had documented recurrence of AF (67 without recurrence). Univariate analysis of demographic characteristics, medications, ECG and echocardiographic parameters revealed that, compared with the group of patients without recurrent AF, the group of those with it included more members of the SAF group (11/27 vs. 13/67, p = 0.039), included more male subjects (22/23 vs. 45/67, p = 0.045), had a larger left atrial volume index (LAVI; 27 +/- 9 vs. 22 +/- 9 ml/m2, p = 0.024) and had lower LA appendage peak emptying velocity (LAAPEV; 42 +/- 15 vs. 55 +/- 22 cm/s, p = 0.01). Multivariate Cox proportional hazards regression analysis adjusted for age, gender and AF group revealed that patients with LAVI <30 ml/m2 and LAAPEV >46 cm/s had the least recurrence of AF (relative risk 0.18, 95% confidence interval 0.06-0.55, vs. with LAVI >30 ml/m2 or LAAPEV <46 cm/s, p = 0.002). Kaplan-Meier probability of freedom from AF recurrence was significantly better when LAVI <30 ml/m2 (log-rank p = 0.02), LAAPEV > 46 cm/s (p = 0.013) or both (p = 0.004). The superiority to predict the rate of sinus rhythm maintenance was the same in the PAF and SAF groups.

CONCLUSIONS

Good responders to rhythm control in the PAF and SAF groups share the characteristics of smaller LA volume and better LAA contractile function, emphasizing the critical role of atrial substrate remodeling in recurrence of AF.

Low frequency of target organ damage in Taiwanese with white coat hypertension

BACKGROUND AND PURPOSE

The clinical importance of white coat hypertension (WCH) remains to be clarified. This study investigated the target organ damage in Taiwanese with WCH.

METHODS

A total of 188 consecutive Taiwanese (88 men and 100 women), aged 26 to 75 years who had an abnormal office casual blood pressure (systolic blood pressure >/= 140 mm Hg or diastolic blood pressure >/= 90 mm Hg or both) and a normal ambulatory blood pressure (ABP) average (systolic ABP average < 140 mm Hg and diastolic ABP average < 90 mm Hg) at the outpatient clinic or from a mass survey were enrolled. Office casual blood pressure measurements were obtained by standard sphygmomanometric methods. Twenty-four-hour blood pressures were recorded by a commercial ambulatory pressure recorder (Del Mar Avionics, Model 1990 Pressurometer IV System). Hypertension-related target organ complications were assessed by electrocardiogram, chest X-ray, urinalysis and eye fundus examinations.

RESULTS

Target organ damage was found in 6.4% of subjects with WCH. Roentgenographic left ventricular hypertrophy (LVH) was found in 1.1% of subjects and electrocardiographic LVH in 2.7%. Proteinuria was found in 1.6% of subjects and retinopathy in 1.1%. The frequencies of various target organ damage were not significantly associated with age, gender and the definition of normal ABP average as 135/85 mm Hg or 140/90 mm Hg.

CONCLUSIONS

WCH represents a low-risk stratum for target organ damage in Taiwanese. These subjects should be identified and followed up regularly. The factors responsible for the low frequency of target organ damage in Taiwanese with WCH need further study.

Radiofrequency ablation of a concealed right anterior accessory pathway associated with right atrial diverticulum in a child

A 9-year-old boy had refractory supraventricular tachycardia and a right atrial (RA) diverticulum as diagnosed by ultrafast computed tomography. An electrophysiological study under transesophageal echocardiography guidance revealed a concealed right anterior accessory pathway passing through the body of the RA diverticulum. Radiofrequency ablation was performed to eliminate retrograde ventriculoatrial conduction.

Activation of the calcineurin-nuclear factor of activated T-cell signal transduction pathway in atrial fibrillation

STUDY OBJECTIVES

The calcineurin-nuclear factor of activated T-cell (NFAT) signal transduction pathway regulates the expression of a plethora of genes in the myocardium. Cytosolic calcium overloading occurs in atrial fibrillation (AF), and this fulfills the condition needed for activation of this pathway. We therefore investigated the NFAT pathway in atrial tissue in a porcine model of AF.

METHODS AND RESULTS

AF was induced in eight adult pigs by rapid atrial pacing. Investigations on the calcineurin and NFAT pathway were performed on transmural left atrial tissue obtained 6 weeks after implantation of the pacemaker (pacing for 4 weeks, and AF without pacing for 2 weeks). In the AF group, the left atrial dimension increased significantly (26 +/- 4 mm vs 31 +/- 4 mm, respectively, p < 0.05 [mean +/- SD]). Calcineurin enzyme activity increased significantly in pigs with AF (n = 8) when compared to control pigs (n = 6) [0.143 +/- 0.034 vs 0.038 +/- 0.063 mmol PO(4)(-) released, p < 0.01]. We found that both NFAT-c3 and NFAT-c4, the downstream effectors of calcineurin, increased significantly in the nuclei in AF tissue using immunoblotting. Translocation of NFAT-c3 and NFAT-c4 into the nuclei was also demonstrated in AF tissue microsections using immunohistochemistry. The electrophoresis mobility shift assay further demonstrated that nuclear extracts from AF tissue had a significantly larger binding capacity for NFAT-specific oligonucleotide probes.

CONCLUSIONS

Our results demonstrate that calcineurin activity was increased in AF with subsequent NFAT-c3 and NFAT-c4 translocation into the nucleus. Activation of this signal transduction pathway may play an important role in the pathogenesis of AF.