Kikuya Uno

Predicting the Need for an Implantable Cardioverter Defibrillator Using Cardiac Metaiodobenzylguanidine Activity Together with Plasma Natriuretic Peptide Concentration or Left Ventricular Function

Despite widespread use of implantable cardioverter defibrillators (ICDs), their cost and the fact that only a certain group of patients fully benefits from the devices require appropriate risk stratification of patients. This study investigated whether altered cardiac autonomic function is associated with the occurrence of ICD discharge or lethal cardiac events. Methods: Fifty-four ICD-treated patients were prospectively followed after assessment of cardiac metaiodobenzylguanidine (MIBG) activity, quantified as the heart-to-mediastinum ratio (HMR), plasma concentration of brain natriuretic peptide (BNP), and left ventricular ejection fraction (LVEF). Patients were divided into 2 groups based on the presence (group A, n = 21) or absence (group B, n = 33) of appropriate ICD discharge during a 15-mo period. Results: Group A had a significantly lower level of MIBG activity and a higher plasma BNP level than did group B. Univariate analysis revealed BNP level, any medication, and late HMR to be significant predictors, and multivariate analysis showed late HMR to be an independent predictor. An HMR of less than 1.95 with a plasma BNP level of more than 187 pg/mL or an LVEF of less than 50% had significantly increased power to predict ICD shock: positive predictive values, 82% (HMR + BNP) and 58% (HMR + LVEF); negative predictive values, 73% (HMR + BNP) and 77% (HMR + LVEF); sensitivities, 45% (HMR + BNP) and 67% (HMR + LVEF); and specificities, 94% (HMR + BNP) and 70% (HMR + LVEF). Conclusion: When combined with plasma BNP concentration or cardiac function, cardiac MIBG activity is closely related to lethal cardiac events and can be used to identify patients who would benefit most from an ICD.

Prevalence of asymptomatic ST segment elevation in right precordial leads with right bundle branch block (Brugada-type ST shift) among the general Japanese population

OBJECTIVE To examine the modality and morbidity of asymptomatic ST segment elevation in leads V1 to V3 with right bundle branch block (Brugada-type ST shift). METHODS 8612 Japanese subjects (5987 men and 2625 women, mean age 49.2 years) who underwent a health check up in 1997 were investigated. Those with Brugada-type ST shift underwent the following further examinations over a two year period after the initial check up: ECG, echocardiogram, 24 hour Holter monitoring, treadmill exercise testing, signal averaged ECG, and slow kinetic sodium channel blocker loading test (cibenzoline, 1.4 mg/kg). RESULTS Asymptomatic Brugada-type ST shift was found in 12 of 8612 (0.14%) subjects. Eleven of these 12 subjects were followed up. Follow up ECG exhibited persistent Brugada-type ST shift in seven of 11 (63.6%) subjects. ST shift was transformed from a saddle back to a coved type in three subjects. None of the subjects had morphological abnormalities or abnormal tachyarrhythmias. Positive late potentials were found in seven of 11 (63.6%) subjects. Augmentation of ST shift was shown by both submaximal exercise and drug administration in one of the 11 subjects (9.1%). CONCLUSIONS Asymptomatic subjects with Brugada-type ST shift were not unusual, at a rate of 0.14% in the general Japanese population. Almost all of the subjects had some abnormalities in non-invasive secondary examinations. Additional and prospective studies are needed to confirm the clinical significance and the prognosis of asymptomatic Brugada-type ST shift.

Assessment of Left Ventricular Ejection Fraction Using Long-Axis Systolic Function Is Independent of Image Quality: A Study of Tissue Doppler Imaging and M-Mode Echocardiography

Background: Quantitative assessment of left ventricular ejection fraction (LVEF) is technically difficult in patients with poor image quality (IQ). Mitral annulus velocity assessed by pulsed tissue Doppler imaging (TDI) and mitral annulus motion assessed by M‐mode echocardiography has been shown to correlate with LVEF. Furthermore, mitral annulus sites are easy to identify even in patients with poor IQ. The purpose of this study was to determine whether these methods are useful for estimating LVEF in patients with poor IQ. Methods: One hundred ten patients underwent TDI and M‐mode echocardiography simultaneously. Mitral annulus velocity and mitral annulus motion were obtained from each of the four mitral annulus sites. Mean mitral annular peak systolic velocities (Sm) and mean mitral annular motions (MAM) were calculated by averaging at each site. IQ was defined according to a previous report. Results: Both Sm and MAM were successfully measured in all patients. Mean Sm and mean MAM correlated with LVEF. These correlations were observed not only in patients with good IQ (p < 0.001, r = 0.61 for mean Sm; p < 0.001, r = 0.61 for mean MAM) or fair IQ (p < 0.001, r = 0.58 for mean Sm; p < 0.001, r = 0.68 for mean MAM) but also in patients with poor IQ (p < 0.05, r = 0.42 for mean Sm, p < 0.001, r = 0.61 for mean MAM). Using optimal cutoff values of mean Sm and mean MAM in each IQ group, sensitivity and specificity for identifying LVEF < 50% were comparable among three IQ groups. Conclusions: Assessment of long‐axis systolic function by TDI and M‐mode echocardiography enables estimation of LVEF even in patients with poor IQ.

Electrocardiographic and echocardiographic abnormalities in patients with arrhythmogenic right ventricular cardiomyopathy and in their pedigrees.

Electrocardiographic and echocardiographic evaluations in 18 patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) and 29 family members (25 males and 25 females from 7 pedigrees) aged 5 to 64 years (mean +/- 1 SD 30 +/- 16) revealed that 5 of 28 ARVC family members (17%) fulfilled ARVC Task Force criteria. Indexes on late potentials of the signal-averaged electrocardiogram had a significant linear correlation with the age of patients with ARVC and of family members with echocardiographic wall motion abnormality.

Superior Type of Atypical AV Nodal Reentrant Tachycardia: Incidence, Characteristics, and Effect of Slow Pathway Ablation

Background: Atypical atrioventricular (AV) nodal reentrant tachycardias (AVNRT) usually exhibit the earliest retrograde atrial activation (ERAA) at the right inferoseptum (Rt‐IS) or proximal coronary sinus (PCS). The purpose of this study was to characterize atypical AVNRT with the ERAA at the right superoseptum (Rt‐SS).

Atrial defibrillation threshold as a novel predictor of clinical outcome of catheter ablation for persistent atrial fibrillation

AIMS Catheter ablation for persistent atrial fibrillation (AF) is currently performed with different procedural endpoints. When AF did not terminate during ablation procedure, electrical cardioversion was performed at different defibrillation threshold (DFT) according to AF characteristics and atrial electrophysiologic substrates. We sought to evaluate the impact of atrial DFT after catheter ablation for persistent AF on clinical outcome. METHODS AND RESULTS We studied 128 patients with persistent AF (age 63±9 years, 106 men). After completion of circumferential pulmonary vein isolation, the left atrial substrate ablation was performed until AF terminated or all identified complex fractionated electrograms were eliminated. If AF did not terminate during ablation, an internal cardioversion protocol was started at 5J and was increased incrementally in 5 J steps until successful cardioversion was accomplished. Procedural AF termination was achieved in 50 patients (Group A). Atrial fibrillation was terminated by cardioversion with DFT≤10 J in 47 patients (Group B) and with DFT>10 J in 31 patients (Group C). At 14±7 follow-up months after 1.3±0.5 sessions, 47 (94%) Group A patients, 42 (89%) Group B patients, and 14 (45%) Group C patients remained in sinus rhythm. In multivariate analysis of Group B and Group C, DFT (hazard ratio 5.54, P<0.001) and AF duration (hazard ratio 3.74, P=0.011) were independent predictors of recurrent arrhythmia. CONCLUSION When AF does not terminate after the completion of predetermined stepwise ablation, further extensive ablation to terminate AF might be unnecessary if the AF can be successfully terminated by electrical cardioversion at low DFT.

Quantification of area and percentage of infarcted myocardium by single photon emission computed tomography with thallium-201: a comparison with serial serum CK-MB measurements.

In order to quantify the size of the infarcted myocardium, two kinds of data processing techniques were applied to single photon emission computed tomography (SPECT) with thallium-201 and its clinical reliability was evaluated by comparing it with the infarct sizing procedure with the serial serum creatine kinase-MB measurements in 14 patients with acute myocardial infarction. After maximum-count circumferential profile analysis, short axis images were reformatted into an unfolded surface map and a bull’s eye view map. The SPECT-determined infarct size was defined as the area or the percentage of hypoperfused myocardium of which the profile count was less than the mean minus 2SD derived from 8 normal subjects. The infarct area was calculated from the number of pixels with an abnormal count and expressed in an unfolded surface map. The percentage was calculated from the number of abnormal profile points and displayed in a bull’s eye view map. A high linear correlation was observed between the enzymatically determined infarct size and the infarct area or the percentage (r=.947, r=.872, respectively), despite underestimations in 2 patients with accompanying right ventricular infarction and overestimations in 2 patients with prior anterior infarction. Moreover, a close negative correlation was found between the left ventricular ejection fraction and the infarct area or the percentage (r=.836, r=.821, respectively).Thus, the semiautomatic techniques for processing thallium-201 SPECT images might contribute to the quantitative estimation and display of infarcted myocardium and have high clinical reliability.

Studies on the Prevalence of Complicated Atrial Arrhythmias, Flutter, and Fibrillation in Patients with Reciprocating Supraventricular Tachycardia Before and After Successful Catheter Ablation

MIYAMOTO, K.‐J., et al.: Studies on the Prevalence of Complicated Atrial Arrhythmias, Flutter, and Fibrillation in Patients with Reciprocating Supraventricular Tachycardia Before and After Successful Catheter Ablation. Atrial flutter and AF are complications in approximately 30% of cases of paroxysmal supraventricular tachycardia (PSVT)‐indicated catheter ablation, and it is of interest to determine if therapeutic modification for PSVT would eliminate combined atrial tachyarrhythmia like atrial flutter and AF. The aim of this study was to determine the incidence and the risk of atrial tachyarrhythmias after catheter ablation of PSVT. A total of 152 patients (age range 12–74, mean 41 ± 17 years) with accessory pathway (n = 106) and/or dual atrioventricular nodal conduction (n = 46) were enrolled in a 2‐year follow‐up program after successful catheter ablation. Possible risks on clinical background (age, sex, PSVT duration, hemodynamic instability during attacks), premature atrial contraction (PACs) on Holter monitoring, echocardiographic left atrial size, and electrophysiological property (insertion site, conduction type, effective refractory period) were evaluated. Atrial flutter and AF were complications in 53 (35%) of the subjects, who were elderly and had a longer PSVT history with a larger left atrial dimension and frequent PACs; however, the electrophysiological properties were similar. After a 2‐year follow‐up period 36 (24%) of the patients still exhibited PAC runs, including 13 (9%) with atrial flutter and AF, each one of whom were complicated with nonlethal cerebral thromboembolism and congestive heart failure. Multiple‐logistic‐regression analysis revealed that advanced age (≥ 41 years, P = 0.0152) and frequent PACs (≥ 1% of total daily QRS counts, P = 0.0426) on Holter monitoring are the risk factors of PAC runs and/or atrial flutter and AF. In conclusion, successful ablation for PSVT is thought to be beneficial for preventing atrial flutter and AF. However, careful follow‐up to monitor for the recurrence and atrial flutter and AF related complications, especially in patients of solitary atrial flutter and AF without reciprocating tachycardia and with frequent PAC.

Studies on Hemodynamic Instability in Paroxysmal Supraventricular Tachycardia: Noninvasive Evaluations by Head‐Up Tilt Testing and Power Spectrum Analysis on Electrocardiographic RR Variation

DOI, A., et al.: Studies on Hemodynamic Instability in Paroxysmal Supraventricular Tachycardia: Noninvasive Evaluations by Head‐Up Tilt Testing and Power Spectrum Analysis on Electrocardiographic RR Variation. Hemodynamic instability is a crucial determinant of the best therapeutic option in paroxysmal supraventricular tachycardia (PSVT). However, it is still unclear if hemodynamic instability is tachycardia dependent or independent. We performed frequency‐domain analysis of electrocardiographic RR variations during induced PSVT and head‐up tilt tests after successful ablation to investigate the role of autonomic vasomotor function in hemodynamic instability during PSVT. Thirty‐six patients with (syncope group, n = 18) and without (nonsyncope group, n = 18) syncope and/or presyncope during PSVT were enrolled in this study. Serial blood pressure, heart rate, and variations in heart rate during induced PSVT and head‐up tilt tests were examined. Initial blood pressure fall and heart rate changes during induced PSVT were greater in the syncope group than in the nonsyncope group. A significant positive linear relationship was found between these two. Delayed blood pressure fall was observed in the syncope group, independent of heart rate changes. Syncope in PSVT could be predicted from the results of head‐up tilt tests with 82% accuracy. Heart rate responses after isoproterenol infusion were significantly greater in the syncope group than in the nonsyncope group. The changes in low frequency to high frequency (LF:HF) values during induced PSVT and head‐up tilt tests were significantly greater in the syncope group than in the nonsyncope group, and an exponential correlation was found between LF:HF changes in both tests. We conclude that PSVT rate and vasomotor reaction are related with hemodynamic instability during PSVT and head‐up tilt testing is a useful method for determining if patients will have syncope during PSVT.

Myocardial Iodine-123-Metaiodobenzylguanidine (123I-MIBG) Imaging in Brugada Syndrome

To the Editor: We read with interest a recent article in Circulation by Wichter et al1 on cardiac autonomic dysfunction in Brugada syndrome. The authors demonstrated that regionally reduced iodine-123-metaiodobenzylguanidine (123I-MIBG) uptake in the inferior and septal left ventricular wall was present in 8 (47%) of 17 patients with Brugada syndrome but in none of 10 age-matched control subjects. The study may provide new insight into the pathogenesis and arrhythmogenesis of Brugada syndrome. However, we have some questions concerning other indices of 123I-MIBG imaging, clinical characteristics of the study patients, and timing of 123I-MIBG imaging. In normal subjects, regional MIBG uptake may be nonhomogeneous and apparently lower in the inferior and septal wall than in the anterior wall2: 80±11% versus 95±5% (mean±SD).3 Additionally, a heterogeneous 123I-MIBG distribution in the left ventricle may be a physiological phenomenon mediated by the parasympathetic nerve fibers predominantly located in the inferior wall. Therefore, it is possible that segmental (inferior and septal) reduction …