Taku Inohara

Endothelin‐1 Induces Myofibrillar Disarray and Contractile Vector Variability in Hypertrophic Cardiomyopathy–Induced Pluripotent Stem Cell–Derived Cardiomyocytes

Background Despite the accumulating genetic and molecular investigations into hypertrophic cardiomyopathy (HCM), it remains unclear how this condition develops and worsens pathologically and clinically in terms of the genetic–environmental interactions. Establishing a human disease model for HCM would help to elucidate these disease mechanisms; however, cardiomyocytes from patients are not easily obtained for basic research. Patient‐specific induced pluripotent stem cells (iPSCs) potentially hold much promise for deciphering the pathogenesis of HCM. The purpose of this study is to elucidate the interactions between genetic backgrounds and environmental factors involved in the disease progression of HCM. Methods and Results We generated iPSCs from 3 patients with HCM and 3 healthy control subjects, and cardiomyocytes were differentiated. The HCM pathological phenotypes were characterized based on morphological properties and high‐speed video imaging. The differences between control and HCM iPSC‐derived cardiomyocytes were mild under baseline conditions in pathological features. To identify candidate disease‐promoting environmental factors, the cardiomyocytes were stimulated by several cardiomyocyte hypertrophy‐promoting factors. Interestingly, endothelin‐1 strongly induced pathological phenotypes such as cardiomyocyte hypertrophy and intracellular myofibrillar disarray in the HCM iPSC‐derived cardiomyocytes. We then reproduced these phenotypes in neonatal cardiomyocytes from the heterozygous Mybpc3‐targeted knock in mice. High‐speed video imaging with motion vector prediction depicted physiological contractile dynamics in the iPSC‐derived cardiomyocytes, which revealed that self‐beating HCM iPSC‐derived single cardiomyocytes stimulated by endothelin‐1 showed variable contractile directions. Conclusions Interactions between the patients genetic backgrounds and the environmental factor endothelin‐1 promote the HCM pathological phenotype and contractile variability in the HCM iPSC‐derived cardiomyocytes.

The challenges in the management of right ventricular infarction.

In recent years, right ventricular (RV) infarction seems to be underdiagnosed in most cases of acute myocardial ischaemia despite its frequent association with inferior-wall and, occasionally, anterior-wall myocardial infarction (MI). However, its initial management is drastically different from that of left ventricular MI, and studies have indicated that RV infarction remains associated with significant morbidity and mortality, even in the mechanical reperfusion era. The pathophysiology of RV infarction involves the interaction between the right and left ventricle (LV), and the mechanism has been clarified with the advent of diagnostic non-invasive modalities, such as echocardiography and cardiac magnetic resonance. In recent years, considerable progress has been made in the treatment of RV infarction; early revascularization remains the cornerstone of the management, and fluid resuscitation, with appropriate target selection, is necessary to maintain appropriate preload. Early recognition in intensive care with clear understanding of the pathophysiology is essential to improve its prognosis. In terms of management, the support strategy for RV dysfunction is different from that for LV dysfunction since the former may often be temporary. Along with early reperfusion, maintenance of an adequate heart rate and atrioventricular synchrony are essential to sustain a sufficient cardiac output in patients with RV infarction. In refractory cases, more intensive mechanical support is required, and new therapeutic options, such as Tandem-Heart or percutaneous cardiopulmonary support systems, are being developed.

Long-Term Outcome of Healthy Participants with Atrial Premature Complex: A 15-Year Follow-Up of the NIPPON DATA 90 Cohort

Background Atrial premature complexes (APC) are among the most frequently encountered electrocardiographic abnormalities. However, their prognostic value among healthy individuals is unclear. This study aimed to clarify the role of APC in predicting cardiovascular events in a large Japanese community cohort using long-term follow-up data. Methods National Integrated Project for Prospective Observation of Non-communicable Disease And its Trends in the Aged, 1990-2005, (NIPPON DATA 90) was a large cohort study of cardiovascular disease (CVD) in Japan. A total of 7692 otherwise healthy participants with no history of myocardial infarction, stroke, atrial fibrillation, or atrial flutter were enrolled (men, 41.5%; mean age, 52.5 ± 13.7 years). Results A total of 64 (0.8%) participants had at least one beat of APC on screening 12-lead electrocardiogram. During the follow-up of 14.0 ± 2.9 years (total, 107,474 patient-years), 338 deaths occurred due to CVD. The association between APC and CVD outcome was assessed using Cox proportional hazard models. Cox regression analysis revealed that the presence of APC was an independent predictor for CVD deaths (HR: 2.03, 95% CI: 1.12–3.66, P = 0.019). The association of APC on CVD death was more evident in participants with hypertension (P-value for interaction, 0.03). Conclusions APC recorded during the screening electrocardiogram are significantly associated with an increased risk of CVD deaths in a Japanese community-dwelling population and are a strong prognostic factor for hypertensive participants.

Streamlining the learning process for TAVI: Insight from a comparative analysis of the OCEAN-TAVI and the massy registries

To facilitate the learning process of transcatheter aortic valve implantation (TAVI) in Japan, unique supporting systems (e.g., on‐site proctor and web‐based screening systems) have been developed. Nevertheless, little is known about real‐world clinical outcomes after TAVI in Japan compared with their European counterparts.

Effect of Estimated Plasma Volume Reduction on Renal Function for Acute Heart Failure Differs Between Patients With Preserved and Reduced Ejection Fraction

Background—The prognostic relevance of plasma volume reduction (PVR) in acute heart failure patients remains unclear because of the confounding hemodynamic effect of left ventricular ejection fraction impairment on kidney function. Methods and Results—Subjects enrolled in the West Tokyo Heart Failure Registry were examined. The PV at admission and discharge was estimated from the subjects’ body weight and its deviation from the ideal body weight. Patients in the top tertile of estimated PVR were classified as PVR+. Of the 381 patients with acute heart failure, 181 (47.5%) had heart failure with preserved ejection fraction (HFpEF). Estimated PVR was associated with worsening renal function in the HFpEF (odds ratio, 3.28; 95% confidence interval, 1.55–6.96; P=0.002) but not in the heart failure with reduced ejection fraction cohort (odds ratio, 1.22; 95% confidence interval, 0.61–2.42; P=0.57). This association in the HFpEF cohort remained significant after adjusting for a history of hypertension and diabetes mellitus and the estimated glomerular filtration rate (odds ratio, 3.34; 95% confidence interval, 1.52–7.33; P=0.003). The use of intravenous diuretics was a significant predictor of PVR in the HFpEF and heart failure with reduced ejection fraction groups. Conclusions—The effect of estimated PVR differs by HF type, and the estimated PVR during hospitalization is a predictor of worsening renal function in patients with HFpEF but not in heart failure with reduced ejection fraction. Clinical Trial Registration—URL: http://www.umin.ac.jp/ctr/index-j.html. Unique identifier: UMIN000001549.

Performance and Validation of the U.S. NCDR Acute Kidney Injury Prediction Model in Japan.

BACKGROUND Stratifying patient risk for acute kidney injury (AKI) prior to percutaneous coronary intervention (PCI) can enable clinicians to tailor their approach to minimize AKI. The National Cardiovascular Data Registry (NCDR) CathPCI Registry recently developed 2 prediction models: for AKI and AKI requiring dialysis (AKI-D). OBJECTIVES This study sought to externally validate the NCDR AKI and AKI-D models in a Japanese population. Determining the generalizability of the U.S. model could support quality improvement efforts in Japan. METHODS The NCDR prediction models were applied to 11,041 consecutive patients in the Japanese multicenter PCI registry. AKI was defined as an absolute increase ≥ 0.3 mg/dl or a relative increase of 50% in serum creatinine, in accordance with the definition of AKI Network criteria; AKI-D was defined as initiation of dialysis after PCI. Discrimination and calibration of the NCDR models were tested in the Japanese cohort. If the model was perfectly calibrated, the slope and intercept would equal 1.0 and 0.0, respectively. RESULTS In the Japanese PCI cohort, AKI and AKI-D occurred in 10.5% and 1.5% of patients, respectively. The NCDR AKI prediction model showed good discrimination (c-statistic = 0.76) and calibration (slope = 0.93 and intercept = -0.10) in both acute and nonacute PCI. The AKI-D prediction model had good discrimination (c-statistic = 0.92), but while the calibration slope was good (1.04), the intercept was significantly underestimated (0.96). However, this was corrected with recalibration (slope = 1.04 and intercept = -0.087). CONCLUSIONS In a Japanese population, the NCDR AKI models validly predict post-procedural AKI and, with recalibration, AKI-D. Prospective use of these models to inform clinical decision making should be tested as a means of reducing AKI after PCI in Japan. (Japan Cardiovascular Database, Percutaneous Coronary Intervention Registry; UMIN R000004736).

Prognostic implication of physical signs of congestion in acute heart failure patients and its association with steady-state biomarker levels

Background Congestive physical findings such as pulmonary rales and third heart sound (S3) are hallmarks of acute heart failure (AHF). However, their role in outcome prediction remains unclear. We sought to investigate the association between congestive physical findings upon admission, steady-state biomarkers at the time of discharge, and long-term outcomes in AHF patients. Methods We analyzed the data of 133 consecutive AHF patients with an established diagnosis of ischemic or non-ischemic (dilated or hypertrophic) cardiomyopathy, admitted to a single-center university hospital between 2006 and 2010. The treating physician prospectively recorded major symptoms and congestive physical findings of AHF: paroxysmal nocturnal dyspnea, orthopnea, pulmonary rales, jugular venous distension (JVD), S3, and edema. The primary endpoint was defined as rehospitalization for HF. Results Majority (63.9%) of the patients had non-ischemic etiology and, at the time of admission, S3 was seen in 69.9% of the patients, JVD in 54.1%, and pulmonary rales in 43.6%. The mean follow-up period was 726 ± 31days. Patients with pulmonary rales (p < 0.001) and S3 (p  =  0.011) had worse readmission rates than those without these findings; the presence of these findings was also associated with elevated troponin T (TnT) levels at the time of discharge (odds ratio [OR] 2.8; p  =  0.02 and OR 2.6; p  =  0.05, respectively). Conclusion Pulmonary rales and S3 were associated with inferior readmission rates and elevated TnT levels on discharge. The worsening of the readmission rate owing to congestive physical findings may be a consequence of on-going myocardial injury.

Incidence and Determinants of Complications in Rotational Atherectomy: Insights From the National Clinical Data (J-PCI Registry)

Background—The usage of rotational atherectomy (RA) is growing in the current percutaneous coronary intervention (PCI) because of the expansion of PCI indication to more complex lesions. However, the complications after RA have been linked to procedure-related morbidity and mortality. The purpose of this study was to investigate the incidence and determinants of complications in RA using a large nationwide registration system in Japan (J-PCI). Methods and Results—The primary composite outcome of this study was defined as the occurrence of in-hospital death, cardiac tamponade, and emergent surgery after RA. A total of 13 335 RA cases (3.2% of registered PCI cases) were analyzed. The composite outcome was observed in 175 cases (1.31%) and included 80 in-hospital deaths (0.60%), 86 tamponades (0.64%), and 24 emergent surgeries (0.18%). The clinical variables associated with occurrence of the composite outcome were age (odds ratio [OR] 1.03 per unit increment, 95% confidence interval [CI] 1.02–1.05), impaired kidney function (OR 1.59, 95% CI 1.15–2.19), previous myocardial infarction (OR 1.69, 95% CI 1.21–2.35), emergent PCI (OR 4.02, 95% CI 1.66–8.27), and triple-vessel disease (versus single-vessel disease: OR 2.17, 95% CI 1.43–3.28). Notably, institutional volume of RA cases was inversely associated with the composite outcomes (high- versus low-volume institution: OR 0.56, 95% CI 0.36–0.89). Conclusions—The reported incidence of important procedure-related complication rate was 1.3%, with each component ranging between 0.2% and 0.6% in J-PCI. Its determinants were both patient related (age, impaired kidney function, and previous myocardial infarction) and procedure related (emergent procedures, number of diseased vessels, and institutional volume of RA).

Prognostic Impact of Renal Dysfunction Does Not Differ According to the Clinical Profiles of Patients: Insight from the Acute Decompensated Heart Failure Syndromes (ATTEND) Registry

Background Renal dysfunction associated with acute decompensated heart failure (ADHF) is associated with impaired outcomes. Its mechanism is attributed to renal arterial hypoperfusion or venous congestion, but its prognostic impact based on each of these clinical profiles requires elucidation. Methods and Results ADHF syndromes registry subjects were evaluated (N = 4,321). Logistic regression modeling calculated adjusted odds ratios (OR) for in-hospital mortality for patients with and without renal dysfunction. Renal dysfunction risk was calculated for subgroups with hypoperfusion-dominant (eg. cold extremities, a low mean blood pressure or a low proportional pulse pressure) or congestion-dominant clinical profiles (eg. peripheral edema, jugular venous distension, or elevated brain natriuretic peptide) to evaluate renal dysfunctions prognostic impact in the context of the two underlying mechanisms. On admission, 2,150 (49.8%) patients aged 73.3±13.6 years had renal dysfunction. Compared with patients without renal dysfunction, those with renal dysfunction were older and had dominant ischemic etiology jugular venous distension, more frequent cold extremities, and higher brain natriuretic peptide levels. Renal dysfunction was associated with in-hospital mortality (OR 2.36; 95% confidence interval 1.75–3.18, p<0.001), and the prognostic impact of renal dysfunction was similar in subgroup of patients with hypoperfusion- or congestion-dominant clinical profiles (p-value for the interaction ranged from 0.104–0.924, and was always >0.05). Conclusions Baseline renal dysfunction was significantly associated with in-hospital mortality in ADHF patients. The prognostic impact of renal dysfunction was the same, regardless of its underlying etiologic mechanism.

Validation of the Get With The Guideline–Heart Failure risk score in Japanese patients and the potential improvement of its discrimination ability by the inclusion of B-type natriuretic peptide level

BACKGROUND Detailed characteristics of patients with acute heart failure (AHF) in Japan have not been elucidated. Furthermore, international application of risk models obtained in the United States has not been validated. METHODS We evaluated the Get With The Guidelines-Heart Failure (GWTG-HF) risk score performance in AHF patients enrolled in the West Tokyo Heart Failure registry, a large, ongoing, prospective, multicenter cohort registry. Variables required for the GWTG-HF risk score were race, age, systolic blood pressure, heart rate, blood urea nitrogen level, sodium concentration, and presence of chronic obstructive pulmonary disease. Score discrimination and calibration were evaluated by the c statistic, Hosmer-Lemeshow statistic, and visual plotting. We conducted additional analyses to determine whether other variables improved the performance of the score. The primary outcome was in-hospital mortality. RESULTS In total, 1,876 patients were admitted for AHF between April 2006 and August 2014. The patients were predominantly men (60.6%), with a mean age of 73.3 ± 13.6 years. Sixty-eight (3.6%) patients died during hospitalization. The GWTG-HF risk score showed acceptable discrimination; the c statistic for in-hospital mortality in this cohort was 0.763 (95% CI, 0.700-0.826). The calibration plot showed good conformance between the predicted and observed in-hospital mortality. Notably, addition of B-type natriuretic peptide level to the conventional GWTG-HF score significantly improved the discrimination (c statistic, 0.818; 95% CI, 0.771-0.865). CONCLUSIONS The GWTG-HF risk score can be applied in Japanese AHF patients with good discrimination and calibration. Furthermore, addition of B-type natriuretic peptide level improves discrimination and could be considered in future risk models.