The utility of zebrafish cardiac arrhythmia model to predict the pathogenicity of KCNQ1 variants.

Genetic testing for inherited arrhythmias and discriminating pathogenic or benign variants from variants of unknown significance (VUS) is essential for gene-based medicine. KCNQ1 is a causative gene of type 1 long QT syndrome (LQTS), and approximately 30% of the variants found in type 1 LQTS are classified as VUS. We studied the role of zebrafish cardiac arrhythmia model in determining the clinical significance of KCNQ1 variants. We generated homozygous kcnq1 deletion zebrafish (kcnq1del/del) using the CRISPR/Cas9 and expressed human Kv7.1/MinK channels in kcnq1del/del embryos. We dissected the hearts from the thorax at 48 h post-fertilization and measured the transmembrane potential of the ventricle in the zebrafish heart. Action potential duration was calculated as the time interval between peak maximum upstroke velocity and 90% repolarization (APD90). The APD90 of kcnq1del/del embryos was 280 ± 47 ms, which was significantly shortened by injecting KCNQ1 wild-type (WT) cRNA and KCNE1 cRNA (168 ± 26 ms, P < 0.01 vs. kcnq1del/del). A study of two pathogenic variants (S277L and T587M) and one VUS (R451Q) associated with clinically definite LQTS showed that the APD90 of kcnq1del/del embryos with these mutant Kv7.1/MinK channels was significantly longer than that of Kv7.1 WT/MinK channels. Given the functional results of the zebrafish model, R451Q could be reevaluated physiologically from VUS to likely pathogenic. In conclusion, functional analysis using in vivo zebrafish cardiac arrhythmia model can be useful for determining the pathogenicity of loss-of-function variants in patients with LQTS.

The endosomal trafficking regulator LITAF controls the cardiac Nav1.5 channel via the ubiquitin ligase NEDD4-2.

The QT interval is a recording of cardiac electrical activity. Previous genome-wide association studies identified genetic variants that modify the QT interval upstream of LITAF (lipopolysaccharide-induced tumor necrosis factor-α factor), a protein encoding a regulator of endosomal trafficking. However, it was not clear how LITAF might impact cardiac excitation. We investigated the effect of LITAF on the voltage-gated sodium channel Nav1.5, which is critical for cardiac depolarization. We show that overexpressed LITAF resulted in a significant increase in the density of Nav1.5-generated voltage-gated sodium current INa and Nav1.5 surface protein levels in rabbit cardiomyocytes and in HEK cells stably expressing Nav1.5. Proximity ligation assays showed co-localization of endogenous LITAF and Nav1.5 in cardiomyocytes, whereas co-immunoprecipitations confirmed they are in the same complex when overexpressed in HEK cells. In vitro data suggest that LITAF interacts with the ubiquitin ligase NEDD4-2, a regulator of Nav1.5. LITAF overexpression down-regulated NEDD4-2 in cardiomyocytes and HEK cells. In HEK cells, LITAF increased ubiquitination and proteasomal degradation of co-expressed NEDD4-2 and significantly blunted the negative effect of NEDD4-2 on INa We conclude that LITAF controls cardiac excitability by promoting degradation of NEDD4-2, which is essential for removal of surface Nav1.5. LITAF-knockout zebrafish showed increased variation in and a nonsignificant 15% prolongation of action potential duration. Computer simulations using a rabbit-cardiomyocyte model demonstrated that changes in Ca2+ and Na+ homeostasis are responsible for the surprisingly modest action potential duration shortening. These computational data thus corroborate findings from several genome-wide association studies that associated LITAF with QT interval variation.

Functional analysis of KCNH2 gene mutations of type 2 long QT syndrome in larval zebrafish using microscopy and electrocardiography.

Heterologous expression systems play a vital role in the characterization of potassium voltage-gated channel subfamily H member 2 (KCNH2) gene mutations, such as E637K which is associated with long QT syndrome type 2 (LQT2). In vivo assays using zebrafish provide a means for testing genetic variants of cardiac disease; however, limited information on the role of the E637K mutation is available from in vivo systems and their utility has yet to be fully exploited in the context of LQT2. We sought to evaluate the ability of the E637K mutant channel to restore normal repolarization in larval zebrafish with a human KCNH2 orthologue, kcnh2a-knockdown. A morpholino (MO) targeting kcnh2a was injected alone or with wild type (WT) or E637K KCNH2 cRNA into zebrafish embryos at the 1-2 cell stage. Cardiac repolarization phenotypes were screened using light microscopy and the QT interval was measured by single lead electrocardiograph (ECG) analysis at 72-h post-fertilization. In the MO alone group, 17% of zebrafish had a normal phenotype; this rate increased to 60% in the WT KCNH2 cRNA injected zebrafish and to 35% in the E637K injected zebrafish. The ECG of larval zebrafish revealed that QTc was significantly prolonged in the MO alone group compared to the control group. Co-injection of WT KCNH2 cRNA shortened the QTc interval, however, that of the E637K did not. We suggest that this in vivo cardiac assay using microscopy and ECG in larval zebrafish offers a reliable approach for risk discrimination of KCNH2 mutations.

Impact of B-Type Natriuretic Peptide Level on Risk Stratification of Thromboembolism and Death in Patients With Nonvalvular Atrial Fibrillation　- The Hokuriku-Plus AF Registry.

BACKGROUND: B-type natriuretic peptide (BNP) may be a predictor of stroke risk in patients with nonvalvular atrial fibrillation (NVAF); because heart failure is associated with the incidence of stroke in AF patients. However, limited data exist regarding the association between BNP at baseline and risks of thromboembolic events (TE) and death in NVAF patients. Methods and Results: We prospectively studied 1,013 NVAF patients (725 men, 72.8±9.7 years old) from the Hokuriku-plus AF Registry to determine the relationship between BNP at baseline and prognosis among Japanese NVAF patients. During the follow-up period (median, 751 days); 31 patients experienced TE and there were 81 cases of TE/all-cause death. For each endpoint we constructed receiver-operating characteristic curves that gave cutoff points of BNP for TE (170 pg/mL) and TE/all-cause death (147 pg/mL). Multivariate analysis with the Cox-proportional hazards model indicated that high BNP was significantly associated with risks of TE (hazard ratio [HR] 3.86; 95% confidence interval [CI] 1.83-8.67; P=0.0003) and TE/all-cause death (HR 2.27; 95% CI 1.45-3.56; P=0.0003). Based on the C-index and net reclassification improvement, the addition of BNP to CHA2DS2-VASc statistically improved the prediction of TE. CONCLUSIONS: In a real-world cohort of Japanese NVAF patients, high BNP was significantly associated with TE and death. Plasma BNP might be a useful biomarker for these adverse clinical events.

Late Gadolinium Enhancement for Prediction of Mutation-Positive Hypertrophic Cardiomyopathy on the Basis of Panel-Wide Sequencing.

BACKGROUND: Cardiac magnetic resonance (CMR) with late gadolinium enhancement (LGE) revealed a substantial variation in the extent of myocardial scarring, a pathological hallmark of hypertrophic cardiomyopathy (HCM). However, few data exist regarding the relationship between the presence of gene mutations and the extent of LGE. Therefore, we aimed to investigate whether variations in the extent of LGE in HCM patients can be explained by the presence or absence of disease-causing mutations.Methods and Results:We analyzed data from 82 unrelated HCM patients who underwent both LGE-CMR and next-generation sequencing. We identified disease-causing sarcomere gene mutations in 44 cases (54%). The extent of LGE on CMR was an independent factor for predicting mutation-positive HCM (odds ratio 2.12 [95% confidence interval 1.51-3.83], P<0.01). The area under the curve of %LGE was greater than that of the conventional Toronto score for predicting the presence of a mutation (0.96 vs. 0.69, P<0.01). Sensitivity, specificity, positive predictive value, and negative predictive value of %LGE (cutoff >8.1%) were 93.2%, 89.5%, 91.1%, and 91.9%, respectively. CONCLUSIONS: The results demonstrated that %LGE clearly discriminated mutation-positive from mutation-negative HCM in a clinically affected HCM population. HCM with few or no myocardial scars may be genetically different from HCM with a higher incidence of myocardial scars.

Age-Specific Differences in the Duration of Prehospital Cardiopulmonary Resuscitation Administered by Emergency Medical Service Providers Necessary to Achieve Favorable Neurological Outcome After Out-of-Hospital Cardiac Arrest.

BACKGROUND: The appropriate duration of prehospital cardiopulmonary resuscitation (CPR)administered by emergency medical service (EMS) providers for patients with out-of-hospital cardiac arrest (OHCA) necessary to achieve 1-month survival with favorable neurological outcome (Cerebral Performance Category 1 or 2, CPC 1-2) is unclear and could differ by age.Methods and Results:We analyzed the records of 35,709 adult OHCA patients with return of spontaneous circulation (ROSC) before hospital arrival in a prospectively recorded Japanese registry between 2011 and 2014. The CPR duration was defined as the time from CPR initiation by EMS providers to prehospital ROSC. The rate of 1-month CPC 1-2 was 21.4% (7,650/35,709). The CPR duration was independently and inversely associated with 1-month CPC 1-2 (adjusted odds ratio, 0.93 per 1-min increment; 95% confidence interval, 0.93-0.94). The CPR duration increased with age (P<0.001). However, the CPR duration beyond which the proportion of OHCA patients with 1-month CPC 1-2 decreased to <1% declined with age: 28 min for patients aged 18-64 years, 25 min for 65-74 years, 23 min for 75-84 years, 20 min for 85-94 years, and 18 min for ≥95 years. CONCLUSIONS: In patients who achieved prehospital ROSC after OHCA, the duration of CPR administered by EMS providers necessary to achieve 1-month CPC 1-2 varied by age.

Improved Survival With Favorable Neurological Outcome in Elderly Individuals With Out-of-Hospital Cardiac Arrest in Japan　- A Nationwide Observational Cohort Study.

BACKGROUND: There is sparse data regarding the survival and neurological outcome of elderly patients with out-of-hospital cardiac arrest (OHCA). METHODS AND RESULTS: OHCA patients (334,730) aged ≥75 years were analyzed using a nationwide, prospective, population-based Japanese OHCA database from 2008 to 2012. The overall 1-month survival with favorable neurological outcome (Cerebral Performance Category Scale, category 1 or 2; CPC 1-2) rate was 0.88%. During the study period, the annual 1-month CPC 1-2 rate in whole OHCA significantly improved (0.73% to 0.96%, P for trend <0.001). In particular, outcomes of OHCA patients aged 75 to 84 years and those aged 85 to 94 years significantly improved (0.98% to 1.28%, P for trend=0.01; 0.46% to 0.70%, P for trend <0.001, respectively). However, in OHCA patients aged ≥95 years, the outcomes did not improve. Multivariate logistic regression analysis indicated that younger age, shockable first documented rhythm, witnessed arrest, earlier emergency medical service (EMS) response time, and cardiac etiology were significantly associated with the 1-month CPC 1-2. Under these conditions, elderly OHCA patients who had cardiac etiology, shockable rhythm and had a witnessed arrest had acceptable 1-month CPC1-2 rate; 7.98% in cases where OHCA was witnessed by family, 15.2% by non-family, and 25.6% by EMS. CONCLUSIONS: The annual 1-month CPC 1-2 rate after OHCA among elderly patients significantly improved, and the resuscitation of elderly patients in a selected population is not futile. (Circ J 2016; 80: 1153-1162).

Lipoprotein(a) in Familial Hypercholesterolemia With Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Gain-of-Function Mutations.

BACKGROUND: It has been shown that serum lipoprotein(a) [Lp(a)] is elevated in familial hypercholesterolemia (FH) with mutation(s) of the LDL receptor (LDLR) gene. However, few data exist regarding Lp(a) levels in FH with gain-of-function mutations of the PCSK9 gene. METHODS AND RESULTS: We evaluated 42 mutation-determined heterozygous FH patients with aPCSK9gain-of-function mutation (FH-PCSK9, mean age 52, mean LDL-C 235 mg/dl), 198 mutation-determined heterozygous FH patients with aLDLRmutation (FH-LDLR, mean age 44, mean LDL-C 217 mg/dl), and 4,015 controls (CONTROL, mean age 56, mean LDL-C 109 mg/dl). We assessed their Lp(a), total cholesterol, triglycerides, HDL-C, LDL-C, use of statins, presence of hypertension, diabetes, chronic kidney disease, smoking, body mass index (BMI) and coronary artery disease (CAD). Multiple regression analysis showed that HDL-C, use of statins, presence of hypertension, smoking, BMI, and Lp(a) were independently associated with the presence of CAD. Under these conditions, the serum levels of Lp(a) in patients with FH were significantly higher than those of the CONTROL group regardless of their causative genes, among the groups propensity score-matched (median Lp(a) 12.6 mg/dl [IQR:9.4-33.9], 21.1 mg/dl [IQR:11.7-34.9], and 5.0 mg/dl [IQR:2.7-8.1] in the FH-LDLR, FH-PCSK9, and CONTROL groups, respectively, P=0.002 for FH-LDLR vs. CONTROL, P=0.002 for FH-PCSK9 vs. CONTROL). CONCLUSIONS: These data demonstrate that serum Lp(a) is elevated in patients with FH caused by PCSK9 gain-of-function mutations to the same level as that in FH caused by LDLR mutations.

Lipoprotein (a) and the Risk of Chronic Kidney Disease in Hospitalized Japanese Patients.

Objective Lipoprotein (a), or Lp (a), has been shown to be associated with the development of chronic kidney disease (CKD) in populations of various ethnicities. This study aimed to investigate the association between serum Lp (a) and CKD in Japanese patients. Methods A total of 6,130 subjects who underwent a serum Lp (a) level assessment for any reason (e.g. any type of surgery requiring prolonged bed rest or risk factors for atherosclerosis, such as hypertension or diabetes) were retrospectively investigated at Kanazawa University Hospital from April 2004 to March 2014. Of these, 1,895 subjects were excluded because of the lack of clinical data. Subjects were assessed for Lp (a), low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides, hypertension, diabetes, smoking, body mass index (BMI), coronary artery disease (CAD), and CKD (stage ≥3). Results When the study subjects were divided into quartiles of Lp (a) levels, significant trends were observed with regard to the presence of CKD (p = 2.7×10-13). A multiple regression analysis showed that Lp (a) was significantly associated with CKD [odds ratio (OR), 1.12; 95% confidence interval (CI), 1.08-1.17; p = 1.3×10-7, per 10 mg/dL], independent of other classical risk factors, including age, gender, BMI, hypertension, diabetes, smoking, LDL cholesterol, and triglycerides. Under these conditions, Lp (a) was significantly associated with CAD (OR = 1.11, 95% CI = 1.06-1.16; p = 1.7×10-6, per 10 mg/dL), independent of other risk factors. Conclusion Serum Lp (a) was associated with CKD, independent of other classical risk factors in a Japanese population.

Impact of functional studies on exome sequence variant interpretation in early-onset cardiac conduction system diseases.

AIMS: The genetic cause of cardiac conduction system disease (CCSD) has not been fully elucidated. Whole-exome sequencing (WES) can detect various genetic variants; however, the identification of pathogenic variants remains a challenge. We aimed to identify pathogenic or likely pathogenic variants in CCSD patients by using WES and 2015 American College of Medical Genetics and Genomics (ACMG) standards and guidelines as well as evaluating the usefulness of functional studies for determining them. METHODS AND RESULTS: We performed WES of 23 probands diagnosed with early-onset (<65 years) CCSD and analysed 117 genes linked to arrhythmogenic diseases or cardiomyopathies. We focused on rare variants (minor allele frequency < 0.1%) that were absent from population databases. Five probands had protein truncating variants in EMD and LMNA which were classified as 'pathogenic' by 2015 ACMG standards and guidelines. To evaluate the functional changes brought about by these variants, we generated a knock-out zebrafish with CRISPR-mediated insertions or deletions of the EMD or LMNA homologs in zebrafish. The mean heart rate and conduction velocities in the CRISPR/Cas9-injected embryos and F2 generation embryos with homozygous deletions were significantly decreased. Twenty-one variants of uncertain significance were identified in 11 probands. Cellular electrophysiological study and in vivo zebrafish cardiac assay showed that two variants in KCNH2 and SCN5A, four variants in SCN10A, and one variant in MYH6 damaged each gene, which resulted in the change of the clinical significance of them from 'Uncertain significance' to 'Likely pathogenic' in six probands. CONCLUSION: Of 23 CCSD probands, we successfully identified pathogenic or likely pathogenic variants in 11 probands (48%). Functional analyses of a cellular electrophysiological study and in vivo zebrafish cardiac assay might be useful for determining the pathogenicity of rare variants in patients with CCSD. SCN10A may be one of the major genes responsible for CCSD.

Duration of cardiopulmonary resuscitation in patients without prehospital return of spontaneous circulation after out-of-hospital cardiac arrest: Results from a severity stratification analysis.

BACKGROUND: The relationship between duration of cardiopulmonary resuscitation (CPR) and post-arrest outcomes based on severity stratification in out-of-hospital cardiac arrest (OHCA) patients without prehospital return of spontaneous circulation (ROSC) remains unclear. METHODS: We analysed 420,959 adult patients without prehospital ROSC in the All-Japan OHCA registry for 4 years. Prehospital CPR duration was defined as the time from CPR initiation by emergency medical service (EMS) providers to hospital arrival. The primary outcome was 1-month neurologically intact survival (cerebral performance category 1 or 2, CPC 1-2). RESULTS: The rate of overall 1-month CPC 1-2 was 0.45% (1899/420,959). Using recursive partitioning analysis to predict 1-month CPC 1-2, we stratified patients into 4 groups with 3 predictors: patients aged <75 years with initial shockable rhythm (1-month CPC 1-2 rate, 6.15%), those aged ≥75 years with initial shockable rhythm (1.32%), those with EMS-witnessed arrest and initial non-shockable rhythm (1.62%), and those with EMS-unwitnessed arrest and initial non-shockable rhythm (0.15%). Prehospital CPR duration was negatively associated with 1-month CPC 1-2 (adjusted odds ratio 0.94 per 1-min increment; 95% confidence interval 0.94-0.95). Prehospital CPR durations beyond which the dynamic probability of 1-month CPC 1-2 decreased to <1% were 26 min, 10 min, 7 min, and at all times in above-mentioned stratification, respectively. CONCLUSIONS: In OHCA patients without prehospital ROSC, those aged <75 years with initial shockable rhythm had acceptable 1-month CPC 1-2 rate. However, CPR efforts lasting 26 min or over before hospital arrival could be futile.

Molecular and functional characterization of familial chylomicronemia syndrome.

BACKGROUND AND AIMS: Familial chylomicronemia syndrome is a rare autosomal recessive disorder leading to severe hypertriglyceridemia (HTG) due to mutations in lipoprotein lipase (LPL)-associated genes. Few data exist on the clinical features of the disorder or on comprehensive genetic approaches to uncover the causative genes and mutations. METHODS: Eight patients diagnosed with familial hyperchylomicronemia with recessive inheritance were included in this study (two males and six females; median age of onset 23.0 years; mean triglyceride level 3446 mg/dl). We evaluated their clinical features, including coronary artery disease using coronary computed tomography, and performed targeted next-generation sequencing on a panel comprising 4813 genes associated with known clinical phenotypes. After standard filtering for allele frequency <1% and in silico annotation prediction, we used three types of variant filtering to identify causative mutations: homozygous mutations in known familial hyperchylomicronemia-associated genes, homozygous mutations with high damaging scores in novel genes, and deleterious mutations within 37 genes known to be associated with HTG. RESULTS: A total of 1810 variants out of the 73,389 identified with 94.3% mean coverage (×20) were rare and nonsynonymous. Among these, our schema detected four pathogenic or likely pathogenic mutations in the LPL gene (p.Ala248LeufsTer4, p.Arg270Cys, p.Ala361Thr, and p.Val227Gly), including one novel mutation and a variant of uncertain significance. Patients harboring LPL gene mutations showed no severe atherosclerotic changes in the coronary arteries, but recurrent pancreatitis with long-term exposure to HTG was observed. CONCLUSIONS: These results demonstrate that LPL gene plays a major role in extreme HTG associated with hyperchylomicronemia, although the condition may not cause severe atherosclerosis.

Oligogenic familial hypercholesterolemia, LDL cholesterol, and coronary artery disease.

BACKGROUND: The genetic background of severe familial hypercholesterolemia (FH) has yet to be determined. OBJECTIVE: We tested if genetic variants associated with low-density lipoprotein (LDL)-altering autosomal recessive diseases influenced LDL cholesterol levels and the odds for coronary artery disease in patients with high LDL cholesterol. METHODS: We recruited 500 individuals with elevated LDL cholesterol levels (≥180 mg/dL or ≥140 mg/dL for subjects <15 years). We sequenced the exons of 3 FH genes (LDLR, apolipoprotein B, and proprotein convertase subtilisin/kexin type 9) and 4 LDL-altering accessory genes (ABCG5, ABCG8, APOE, and LDL receptor adaptor protein 1). In addition, 4 single nucleotide polymorphisms associated with polygenic FH in East Asian subjects were genotyped. Oligogenic FH patients were defined as those who harbored damaging variants of both conventional FH genes and LDL-altering accessory genes. RESULTS: We identified damaging variants of conventional FH genes in 248 participants (50%). We also detected damaging variants in accessory genes in 57 patients (11%) and identified oligogenic FH in 27 of these patients (5%). Polygenic score in the subjects without any FH mutations was significantly higher than those in any other groups. Compared with monogenic FH, oligogenic FH exhibited significantly higher LDL cholesterol (265 mg/dL, 95% confidence interval [CI] 216-312, and 210 mg/dL, 95% CI 189-243; P = .04). Oligogenic FH exhibited higher odds for coronary artery disease when compared with monogenic FH, although it did not reach statistical significance (odds ratio 1.41, 95% CI 0.68-2.21, P = .24). CONCLUSIONS: Among patients with elevated LDL cholesterol, those with oligogenic FH had higher LDL cholesterol than monogenic FH.

Prehospital predictors of neurological outcomes in out-of-hospital cardiac arrest patients aged 95 years and older: A nationwide population-based observational study.

BACKGROUND: Population aging has rapidly progressed in Japan. However, few data exist regarding the characteristics of extremely elderly patients with out-of-hospital cardiac arrest (OHCA). We aimed to determine the prehospital predictors of one-month survival with favorable neurological outcomes (Cerebral Performance Category scale, category 1 or 2; CPC 1-2) in this population. METHODS: We investigated 23,520 OHCA patients aged ≥95 years from a prospectively recorded, nationwide, Utstein-style Japanese database between 2008 and 2012. The primary study endpoint was one-month CPC 1-2 after OHCA. RESULTS: The one-month CPC 1-2 rate was 0.27% (63/23,520). Only two variables were significantly associated with one-month CPC 1-2 in a multivariate logistic regression model: prehospital return of spontaneous circulation (ROSC) [adjusted odds ratio (aOR), 94.4; 95% confidential interval (CI), 50.1-191.7] and emergency medical service (EMS)-witnessed arrest (aOR, 5.1; 95% CI, 2.6-10.2). When stratified by these two predictors, the one-month CPC 1-2 rates were 20.2% (18/89) for patients who had both prehospital ROSC and EMS-witnessed arrest, 4.2% (33/783) for those who had prehospital ROSC without EMS-witnessed arrest, 0.28% (3/1065) for those who had EMS-witnessed arrest without prehospital ROSC, and 0.04% (9/21,583) for those who had neither predictor, respectively. CONCLUSIONS: The crucial prehospital predictors for one-month CPC 1-2 in elderly OHCA patients aged ≥95 years in Japan were prehospital ROSC and EMS-witnessed arrest and the former was the predominant predictor.

J Waves for Predicting Cardiac Events in Hypertrophic Cardiomyopathy.

OBJECTIVES: This study sought to investigate whether the presence of J waves was associated with cardiac events in patients with hypertrophic cardiomyopathy (HCM). BACKGROUND: It has been uncertain whether the presence of J waves predicts life-threatening cardiac events in patients with HCM. METHODS: This study evaluated consecutive 338 patients with HCM (207 men; age 61 ± 17 years of age). A J-wave was defined as J-point elevation >0.1 mV in at least 2 contiguous inferior and/or lateral leads. Cardiac events were defined as sudden cardiac death, ventricular fibrillation or sustained ventricular tachycardia, or appropriate implantable cardiac defibrillator therapy. The study also investigated whether adding the J-wave in a conventional risk model improved a prediction of cardiac events. RESULTS: J waves were seen in 46 (13.6%) patients at registration. Cardiac events occurred in 31 patients (9.2%) during median follow-up of 4.9 years (interquartile range: 2.6 to 7.1 years). In a Cox proportional hazards model, the presence of J waves was significantly associated with cardiac events (adjusted hazard ratio: 4.01; 95% confidence interval [CI]: 1.78 to 9.05; p = 0.001). Compared with the conventional risk model, the model using J waves in addition to conventional risks better predicted cardiac events (net reclassification improvement, 0.55; 95% CI: 0.20 to 0.90; p = 0.002). CONCLUSIONS: The presence of J waves was significantly associated with cardiac events in HCM. Adding J waves to conventional cardiac risk factors improved prediction of cardiac events. Further confirmatory studies are needed before considering J-point elevation as a marker of risk for use in making management decisions regarding risk in patients with HCM.

Age-specific differences in prognostic significance of rhythm conversion from initial non-shockable to shockable rhythm and subsequent shock delivery in out-of-hospital cardiac arrest.

BACKGROUND: Early rhythm conversion from an initial non-shockable to a shockable rhythm and subsequent shock delivery in patients with out-of-hospital cardiac arrest (OHCA) has been associated with favourable neurological outcome (Cerebral Performance Category score 1 or 2; CPC 1-2). We hypothesized that the prognostic significance of rhythm conversion and subsequent shock delivery differs by age and time from initiation of cardiopulmonary resuscitation (CPR) by emergency medical service (EMS) providers to first defibrillation (shock delivery time). METHODS: We analysed 430,443 OHCA patients with an initial non-shockable rhythm using a prospective Japanese Utstein-style database from 2011 to 2014. The primary endpoint was 1-month CPC 1-2. RESULTS: Multivariate logistic regression revealed that rhythm conversion and subsequent shock delivery is positively associated with 1-month CPC 1-2: the adjusted odds ratio was 6.09 (95% confidence interval: 3.65-9.75) for shock delivery time <10min and 3.34 (2.58-4.27) for 10-19min in patients aged 18-64 years, and 3.16 (1.45-6.09) for <10min and 2.17 (1.51-3.03) for 10-19min in patients aged 65-74 years. However, it is negatively associated with 1-month CPC 1-2 for shock delivery time of 20-59min in patients aged 75-84 years (0.55; 0.27-0.98) and ≥85 years (0.17; 0.03-0.53). CONCLUSIONS: Early rhythm conversion from an initial non-shockable to a shockable rhythm and subsequent shock delivery is associated with increased odds of 1-month CPC 1-2 in OHCA patients aged 18-74 years but not in those aged ≥75 years.

Whole exome sequencing combined with integrated variant annotation prediction identifies a causative myosin essential light chain variant in hypertrophic cardiomyopathy.

BACKGROUND: The development of candidate gene approaches to enable molecular diagnosis of hypertrophic cardiomyopathy (HCM) has required extensive and prolonged efforts. Whole exome sequencing (WES) technologies have already accelerated genetic studies of Mendelian disorders, yielding approximately 30% diagnostic success. As a result, there is great interest in extending the use of WES to any of Mendelian diseases. This study investigated the potential of WES for molecular diagnosis of HCM. METHODS: WES was performed on seven relatives from a large HCM family with a clear HCM phenotype (five clinically affected and two unaffected) in the Kanazawa University Hypertrophic Cardiomyopathy Registry. Serial bioinformatics filtering methods as well as using combined annotation dependent depletion (CADD) score and high heart expression (HHE) gene data were applied to detect the causative variant. Moreover, additional carriers of the variant were investigated in the HCM registry, and clinical characteristics harboring the variant were collected and evaluated. RESULTS: WES detected 60020 rare variants in the large HCM family. Of those, 3439 were missense, nonsense, splice-site, or frameshift variants. After genotype-phenotype matching, 13 putative variants remained. Using CADD score and HHE gene data, the number of candidates was reduced to one, a variant in the myosin essential light chain (MYL3, NM_000258.2:c.281G>A, p.Arg94His) that was shared by the five affected subjects. Additional screening of the HCM registry (n=600) identified two more subjects with this variant. Serial assessments of the variant carriers revealed the following phenotypic characteristics: (1) disease-penetrance of 88%; (2) all clinically affected carriers exhibited asymmetric septal hypertrophy with a substantial maximum left ventricular wall thickness of 18±3mm without any obstruction. CONCLUSIONS: WES combined with CADD score and HHE gene data may be useful even in HCM. Furthermore, the MYL3 Arg94His variant was associated with high disease penetrance and substantial interventricular septal hypertrophy.

Usefulness of Electrocardiographic Voltage to Determine Myocardial Fibrosis in Hypertrophic Cardiomyopathy.

Classic electrocardiographic (ECG) voltage indexes have been applied to screen for left ventricular (LV) hypertrophy in hypertrophic cardiomyopathy (HC). However, it is unclear whether low ECG voltage reflects deteriorated electrical forces because of replacement of the myocardium by fibrotic tissues in HC. We investigated correlations between classic ECG voltage indexes (Cornell, total QRS voltage, and Sokolow-Lyon) and cardiac magnetic resonance (CMR) parameters focusing on the impact of low ECG voltage on the LV ejection fraction (LVEF) and myocardial fibrosis in HC. We studied 108 consecutive patients with HC who underwent CMR imaging with late gadolinium enhancement (LGE). Nineteen patients with complete right or left bundle branch block were excluded, leaving 89 patients for analysis (age 61.0 ± 13.9 years; 58 men). Of the 3 voltage indexes, the total QRS voltage and Sokolow-Lyon indexes were positively correlated with LVEF. For discriminating patients with end-stage HC (LVEF <50%) from patients with HC and preserved LVEF (≥ 50%), receiver-operating characteristic analysis revealed an excellent area under the curve of 0.87 for the total QRS voltage index and 0.90 for the Sokolow-Lyon index, whereas the area under the curve for the Cornell index was only 0.54 (p <0.01). Moreover, these 2 voltage indexes were negatively correlated with the extent of LGE-determined myocardial fibrosis when adjusted by the LV maximal wall thickness. In conclusion, low ECG voltage indexes may reflect increased myocardial fibrosis in patients with HC.

Impact of Distal Protection with Filter-Type Device on Long-term Outcome after Percutaneous Coronary Intervention for Acute Myocardial Infarction: Clinical Results with Filtrap®.

AIM: Although distal embolization during percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) deteriorates cardiac function, whether distal protection (DP) can improve prognosis is still controversial. We investigated whether a filter-type DP device, Filtrap®, could improve long-term outcomes after PCI for AMI. METHOD: We studied 164 patients (130 men, mean age: 65.7 years) who underwent PCI. Patients were divided into two groups based on the use of Filtrap®. The occurrence of congestive heart failure (CHF) and major adverse cardiac events (MACE) defined as cardiac death, recurrent AMI, and target vessel revascularization were compared. RESULT: Between DP (n=53, 41 men, mean age: 65.5 years) and non-DP (n=111, 89 men, mean age: 65.8 years) groups, although there was significantly greater plaque area in the DP group than in the non-DP group, there were no significant differences in coronary reperfusion flow after PCI. Interestingly, patients with CHF in the non-DP group exhibited a higher CK level than those in the DP group. During a 2-year follow-up period, cumulative CHF was significantly lower in the DP group than in the non-DP group (log-rank p=0.018), and there was no significant difference in the MACE rate (log-rank p=0.238). The use of DP device could not predict MACE, but could predict CHF by multivariate analysis (odds ratio=0.099, 95% CI: 0.02-0.42, p=0.005). CONCLUSION: These results demonstrate that favorable clinical outcomes could be achieved by the filter-type DP device in AMI, particularly in patients with CHF.

Assessment of coronary atherosclerosis in patients with familial hypercholesterolemia by coronary computed tomography angiography.

The aims of this study were (1) to determine whether the accumulation of coronary plaque burden assessed with coronary computed tomography angiography (CCTA) can predict future events and (2) to estimate the onset and progression of coronary atherosclerosis in patients with familial hypercholesterolemia (FH). Consecutive 101 Japanese patients with heterozygous FH (men = 52, mean age 56 ± 16 years, mean low-density lipoprotein cholesterol 264 ± 58 mg/dl) who underwent 64-detector row CCTA without known coronary artery disease were retrospectively evaluated by assigning a score (0 to 5) to each of 17 coronary artery segments according to the Society of Cardiovascular Computed Tomography guidelines. Those scores were summed and subsequently natural log transformed. The periods to major adverse cardiac events (MACE) were estimated using multivariable Cox proportional hazards models. During the follow-up period (median 941 days), 21 MACE had occurred. Receiver operating characteristic curve analyses identified a plaque burden score of 3.35 (raw score 28.5) as the optimal cutoff for predicting a worse prognosis. Multivariate Cox regression analysis identified the presence of a plaque score ≥3.35 as a significant independent predictor of MACE (hazard ratio = 3.65; 95% confidence interval 1.32 to 25.84, p <0.05). The regression equations were Y = 0.68X - 15.6 (r = 0.54, p <0.05) in male and Y = 0.74X - 24.8 (r = 0.69, p <0.05) in female patients with heterozygous FH. In conclusion, coronary plaque burden identified in a noninvasive, quantitative manner was significantly associated with future coronary events in Japanese patients with heterozygous FH and that coronary atherosclerosis may start to develop, on average, at age 23 and 34 years in male and female patients with heterozygous FH, respectively.