Eiichi Masuta

Assessment of QT Intervals and Prevalence of Short QT Syndrome in Japan

Long QT syndrome causes ventricular tachyarrhythmias and sudden death. Recently, a short QT interval has also been shown to be associated with an increased risk of tachyarrhythmia and sudden death. However, the prevalence of short QT syndrome is not well‐known.

Long QT syndrome and associated gene mutation carriers in Japanese children: results from ECG screening examinations.

LQTS (long QT syndrome) is caused by mutations in cardiac ion channel genes; however, the prevalence of LQTS in the general population is not well known. In the present study, we prospectively estimated the prevalence of LQTS and analysed the associated mutation carriers in Japanese children. ECGs were recorded from 7961 Japanese school children (4044 males; mean age, 9.9+/-3.0 years). ECGs were examined again for children who had prolonged QTc (corrected QT) intervals in the initial ECGs, and their QT intervals were measured manually. An LQTS score was determined according to Schwartzs criteria, and ion channel genes were analysed. In vitro characterization of the identified mutants was performed by heterologous expression experiments. Three subjects were assigned to a high probability of LQTS (3.5< or = LQTS score), and eight subjects to an intermediate probability (1.0< LQTS score < or =3.0). Genetic analysis of these II subjects identified three KCNH2 mutations (M124T, 547-553 del GGCGGCG and 2311-2332 del/ins TC). In contrast, no mutations were identified in the 15 subjects with a low probability of LQTS. Electrophysiological studies showed that both the M124T and the 547-553 del GGCGGCG KCNH2 did not suppress the wild-type KCNH2 channel in a dominant-negative manner. These results demonstrate that, in a random sample of healthy Japanese children, the prevalence of a high probability of LQTS is 0.038% (three in 7961), and that LQTS mutation carriers can be identified in at least 0.038% (one in 2653). Furthermore, large-scale genetic studies will be needed to clarify the real prevalence of LQTS by gene-carrier status, as it may have been underestimated in the present study.

Differences in the diagnostic value of various criteria of negative T waves for hypertrophic cardiomyopathy based on a molecular genetic diagnosis

Differences in the diagnostic value of a variety of definitions of negative T waves for HCM (hypertrophic cardiomyopathy) have not yet been clarified, resulting in a number of definitions being applied in previous studies. The aim of the present study was to determine the most accurate diagnostic definition of negative T waves for HCM in genotyped populations. Electrocardiographic and echocardiographic findings were analysed in 161 genotyped subjects (97 carriers and 64 non-carriers). We applied three different criteria that have been used in previous studies: Criterion 1, negative T wave >10 mm in depth in any leads; Criterion 2, negative T wave >3 mm in depth in at least two leads; and Criterion 3, negative T wave >1 mm in depth in at least two leads. Of the three criteria, Criterion 3 had the highest sensitivity (43% compared with 5 and 26% in Criterion 1 and Criterion 2 respectively; P<0.0001) and retained a specificity of 95%, resulting in the highest accuracy. In comparison with abnormal Q waves, negative T waves for Criterion 3 had a lower sensitivity in detecting carriers without LVH (left ventricular hypertrophy) (12.9% for negative T waves compared with 22.6% for abnormal Q waves). On the other hand, in detecting carriers with LVH, the sensitivity of negative T waves increased in a stepwise direction with the increasing extent of LVH (P<0.001), whereas there was less association between the sensitivity of abnormal Q waves and the extent of LVH. In conclusion, Criterion 3 for negative T waves may be the most accurate definition of HCM based on genetic diagnoses. Negative T waves may show different diagnostic value according to the different criteria and phenotypes in genotyped populations with HCM.

Increased extent of myocardial fibrosis in genotyped hypertrophic cardiomyopathy with ventricular tachyarrhythmias

BACKGROUNDnOccurrence of malignant ventricular tachyarrhythmias such as ventricular tachycardia and fibrillation (VT/VF) in hypertrophic cardiomyopathy (HCM) can be related to the extent of myocardial fibrosis. Although late gadolinium enhancement (LGE) on cardiovascular magnetic resonance (CMR) imaging has been used to detect myocardial fibrosis, few data exist regarding relationships between CMR-determined myocardial fibrosis and VT/VF in genotyped HCM populations.nnnOBJECTIVEnWe retrospectively investigated whether the extent of LGE can be increased in HCM patients with VT/VF compared to those without VT/VF in the genotyped HCM population.nnnMETHODS AND RESULTSnWe studied 35 HCM patients harboring sarcomere gene mutations (TNNI3=22, MYBPC3=12, MYH7=1) who underwent both CMR imaging and 24-h ambulatory electrocardiographic monitoring. VT/VF were identified in 6 patients (2 men, mean age 55.0 years). The extent of LGE was significantly increased in patients with VT/VF (n=6) compared with those without VT/VF (n=29) (18.6±14.4% vs. 8.3±11.4%, p=0.04), although the LGE extent was not an independent predictor for the occurrence of VT/VF. Applying a cut-off point ≥3.25%, episodes of VT/VF were identified with a sensitivity of 100%, specificity of 51.7%, positive predictive value of 30%, negative predictive value of 100%, and the area under the curve of 0.767 (95% confidence interval: 0.590-0.944).nnnCONCLUSIONnThese results demonstrate that myocardial fibrosis determined by CMR imaging may be increased in genotyped HCM patients with episodes of VT/VF. A further prospective study will be needed to clarify the association between the LGE extent and arrhythmic events in HCM patients harboring sarcomere gene mutations.

A KCR1 variant implicated in susceptibility to the long QT syndrome.

The acquired long QT syndrome (aLQTS) is frequently associated with extrinsic and intrinsic risk factors including therapeutic agents that inadvertently inhibit the KCNH2 K(+) channel that underlies the repolarizing I(Kr) current in the heart. Previous reports demonstrated that K(+) channel regulator 1 (KCR1) diminishes KCNH2 drug sensitivity and may protect susceptible patients from developing aLQTS. Here, we describe a novel variant of KCR1 (E33D) isolated from a patient with ventricular fibrillation and significant QT prolongation. We recorded the KCNH2 current (I(KCNH2)) from CHO-K1 cells transfected with KCNH2 plus wild type (WT) or mutant KCR1 cDNA, using whole cell patch-clamp techniques and assessed the development of I(KCNH2) inhibition in response to well-characterized KCNH2 inhibitors. Unlike KCR1 WT, the E33D variant did not protect KCNH2 from the effects of class I antiarrhythmic drugs such as quinidine or class III antiarrhythmic drugs including dofetilide and sotalol. The remaining current of the KCNH2 WT+KCR1 E33D channel after 100 pulses in the presence of each drug was similar to that of KCNH2 alone. Simulated conditions of hypokalemia (1mM [K(+)](o)) produced no significant difference in the fraction of the current that was protected from dofetilide inhibition with KCR1 WT or E33D. The previously described α-glucosyltransferase activity of KCR1 was found to be compromised in KCR1 E33D in a yeast expression system. Our findings suggest that KCR1 genetic variations that diminish the ability of KCR1 to protect KCNH2 from inhibition by commonly used therapeutic agents constitute a risk factor for the aLQTS.

A novel mutation in the cardiac myosin-binding protein C gene is responsible for hypertrophic cardiomyopathy with severe ventricular hypertrophy and sudden death

It has been demonstrated previously that clinical phenotypes of HCM (hypertrophic cardiomyopathy) caused by mutations in the cardiac MyBP-C (myosin-binding protein C) gene show late onset, low penetrance and favourable clinical course. However, we have encountered severe phenotypes in several carriers of the MyBP-C gene mutations. The aim of the present study was to screen novel MyBP-C gene mutations in patients with HCM and to investigate the genetic differences in affected subjects with severe phenotypes. The MyBP-C gene was screened in 292 Japanese probands with HCM, and a novel c.2067+1G-->A mutation was present in 15 subjects in five families. Clinical phenotypes of carriers of the c.2067+1G-->A mutation were compared with those of a previously identified Arg820Gln (Arg820-->Gln) mutation in the MyBP-C gene. The disease penetrance in subjects aged > or =30 years was 90% in carriers of the c.2067+1G-->A mutation and 61% in carriers of the Arg820Gln mutation. Sudden death occurred in four subjects from three families with the c.2067+1G-->A mutation and in two subjects from one family with the Arg820Gln mutation. Two carriers of the c.2067+1G-->A mutation had substantial hypertrophy (maximal wall thickness > or =30 mm). In contrast, two carriers of the Arg820Gln mutation had end-stage HCM. In conclusion, the c.2067+1G-->A mutation is associated with HCM with substantial hypertrophy and moderate incidence of sudden death, whereas the Arg820Gln mutation is associated with end-stage HCM. These observations may provide important prognostic information regarding the clinical practice of HCM.

High Sensitivity of Late Gadolinium Enhancement for Predicting Microscopic Myocardial Scarring in Biopsied Specimens in Hypertrophic Cardiomyopathy

Background Myocardial scarring can be assessed by cardiac magnetic resonance imaging with late gadolinium enhancement and by endomyocardial biopsy. However, accuracy of late gadolinium enhancement for predicting microscopic myocardial scarring in biopsied specimens remains unknown in hypertrophic cardiomyopathy. We investigated whether late gadolinium enhancement in the whole heart reflects microscopic myocardial scarring in the small biopsied specimens in hypertrophic cardiomyopathy. Methods and Results Twenty-one consecutive patients with hypertrophic cardiomyopathy who were examined both by cardiac magnetic resonance imaging and by endomyocardial biopsy were retrospectively studied. The right interventricular septum was the target site for endomyocardial biopsy in all patients. Late gadolinium enhancement in the ventricular septum had an excellent sensitivity (100%) with a low specificity (40%) for predicting microscopic myocardial scarring in biopsied specimens. The sensitivity of late gadolinium enhancement in the whole heart remained 100% with a specificity of 27% for predicting microscopic myocardial scarring in biopsied specimens. Quantitative assessments of fibrosis revealed that the extent of late gadolinium enhancement in the whole heart was the only independent variable related to the microscopic collagen fraction in biopsied specimens (β u200a=u200a 0.59, 95% confident interval: 0.15 – 1.0, p u200a=u200a 0.012). Conclusions Although there was a compromise in the specificity, the sensitivity of late gadolinium enhancement was excellent for prediction of microscopic myocardial scarring in hypertrophic cardiomyopathy. Moreover, the severity of late gadolinium enhancement was independently associated with the quantitative collagen fraction in biopsied specimens in hypertrophic cardiomyopathy. These findings indicate that late gadolinium enhancement can reflect both the presence and the extent of microscopic myocardial scarring in the small biopsied specimens in hypertrophic cardiomyopathy.

Idiopathic dissection from left subclavian artery to brachial artery: Spontaneous repair with conservative management

We report an unusual case of a 58-year-old female with idiopathic dissection of the left subclavian artery to the brachial artery which provoked vessel narrowing in the acute phase and was spontaneously repaired without surgical procedures in the chronic phase. We describe the serial imaging findings of the angiography and ultrasonography which demonstrate restoration of the dissection. In carefully selected patients, conservative management could be an alternative treatment to surgery or stenting with an excellent outcome.

Perfect Correspondence of Mitral Valve Perforation Using Real-Time 3-Dimensional Transesophageal Echocardiography

![Figure][1] nn[![Graphic][3] ][3]nnnnCritical information about the exact anatomic characteristics of the mitral valve can be obtained using real-time 3-dimensional transesophageal echocardiography (RT3D TEE), which could be used in planning an appropriate intervention strategy. The

Baseline and Serial Changes in Urinary Albumin-to-creatinine Ratio in Patients with Hypertension Treated by Telmisartan

Background: Worsening of renal function (WRF) during the hospitalization of acute decompensated heart failure (ADHF) is associated with in-hospital mortality, however the influence of WRF after discharge on the re-hospitalization is not well known in patients with ADHF.Methods:We investigated the National CardiovAScular Center Acute DEcompensated Heart Failure (nCASCADE) database, a unicenter registry designed to prospectively collect data on each episode of hospitalization for ADHF(n5545). The sample consisted of 78 patients who had at least two hospitalizations during our observation period (2006-2009). We compared the clinical characteristics between the first (1st) and second (2nd) hospitalization. Results: In our study population, the age at the 1st hospitalization was 75612 years old, and the ratio of male was 54%. The period to the rehospitalization was 2106182 days. In the 2nd hospitalization, systolic blood pressure at admissions decreased (138mmHg vs 129mmHg, p!0.05), serum Cre level elevated (1.27mg/dl vs 1.48mg/dl, p!0.05), and anemia worsened (11.7g/dl vs 11.1g/dl, p!0.005) compared with the 1st hospitalization. However, there were no significant differences in left ventricle fractional shortening (20.8% vs 21.6%, NS) and serum brain natriuretic peptide levels (1107pg/ml vs 1241pg/ml, NS) between the two groups. The in-hospital mortality of the 2nd hospitalization was 9%. Conclusion: In patients with ADHF, decline of renal function by the rehospitalization may be associated with prognosis aggravation.