Advances in nuclear reprogramming technology have enabled the dedifferentiation and transdifferentiation of mammalian cells. Forced induction of the key transcription factors constituting a transcriptional network can convert cells back to their pluripotent status or directly to another cell fate without inducing pluripotency. To date, direct conversion to several cell types, including cardiomyocytes, various types of neurons, and pancreatic β-cells, has been reported. We previously demonstrated direct lineage reprogramming of adult fibroblasts into induced endothelial cells (iECs) in mice and humans. In contrast to induced pluripotent stem cells, for which there is consensus on the criteria defining pluripotency, such criteria have not yet been established in the field of direct conversion. We thus suggest that careful assessment of the status of converted cells using genetic and epigenetic profiling, various functional assays, and the use of multiple readouts is essential to determine successful conversion. As direct conversion does not go through pluripotent status, this technique can be utilized for therapeutic purposes without the risk of tumorigenesis. Further, direct conversion can be induced in vivo by gene delivery to the target tissue or organ in situ. Thus, direct conversion technology can be developed into cell therapy or gene therapy for regenerative purposes. Here, we review the potential and future directions of direct cell fate conversion and iECs.

Background: The clinical features of heart failure (HF) in patients with hypertrophic cardiomyopathy (HCM) in Japan have not been fully elucidated.

Methods and Results: In 293 patients with HCM (median age at registration, 65 (57–72) years) in a prospective cardiomyopathy registration network in Kochi Prefecture (Kochi RYOMA study), HF events (HF death or hospitalization for HF) occurred in 35 patients (11.9%) (median age, 76 (69–80) years), including 11 HF deaths during a median follow-up of 6.1 years. The 5-year HF events rate was 9.6%. Atrial fibrillation, low percentage of fractional shortening, and high B-type natriuretic peptide level at registration were predictors of HF events. The combination of these 3 factors had a relatively high positive predictive value (55%) for HF events and none of them had a high negative predictive value (99%). There were 4 types of HF profile: left ventricular (LV) systolic dysfunction (40%), severe LV diastolic dysfunction (34%), LV outflow tract obstruction (LVOTO) (20%), and primary mitral regurgitation (MR) (6%). HF deaths occurred in patients with LV systolic dysfunction or LV diastolic dysfunction, but none of patients with LVOTO or primary MR due to additional invasive therapies.

Conclusions: In a Japanese HCM cohort, HF was an important complication, requiring careful follow-up and appropriate treatment.

Background: There has been no nationwide survey on the prognosis of pediatric restrictive cardiomyopathy (RCM) in Japan; therefore, this retrospective multicentered study was designed to investigate the long-term survival rate of pediatric patients with RCM in Japan.

Methods and Results: A multicentered, retrospective observational study was performed between 1990 and 2014 and included patients diagnosed with RCM who were aged <18 years from 18 Japanese institutions. A total of 54 patients were diagnosed with RCM. The median age at diagnosis was 4.4 years, and the median duration of observation was 2.2 years at the time of this study. Of these patients, 54% had symptoms, including heart failure. Twelve patients died without heart transplantation, mostly due to heart failure. The median time to death from diagnosis was 2.5 years. Freedom from death at 1, 5, and 10 years was 91%, 68%, and 62%, respectively. Death occurred within 5 years of diagnosis in most patients. Twenty-two patients underwent heart transplantation. Freedom from heart transplantation at 1, 5, and 10 years was 77%, 58%, and 53%, respectively. Freedom from death or heart transplantation at 1, 5, and 10 years was 72%, 40%, and 34%, respectively. The presence of symptoms was a risk factor for death or transplantation.

Conclusions: The prognosis of pediatric RCM is poor, and the heart transplantation rate is low in Japan.

Background: The objective of this study is to investigate the effect of preoperative diabetes on all-cause mortality and major postoperative complications among patients with continuous-flow left ventricular assist device (LVAD) by using data from a national database.

Methods and Results: The 545 study patients who underwent primary HeartMateII implantation between 2013 and 2019 were divided into 2 groups according to their diabetes mellitus (DM) status; patients with DM (n=116) and patients without DM (n=429). First, the on-device survival and incidence of adverse events were evaluated. Second, after adjusting for patients’ backgrounds, the change of laboratory data in the 2 groups were compared. Overall, on-device survival at 1, 2, and 3 years was almost equivalent between the 2 groups; it was 95%, 94%, and 91% in patients without DM, and 93%, 91%m and 91% in patients with DM (P=0.468) The incidence of adverse events was similar between 2 groups of patients, except for driveline exit site infection in the adjusted cohort. Cox proportional hazards regression analysis revealed younger age (HR: 0.98 (95% confidence interval (CI): 0.97–0.99, P=0.001) and presence of DM (HR: 1.83 (95% CI: 1.14–2.88), P=0.016) as significant predictors of driveline infection. Laboratory findings revealed no differences between groups throughout the periods.

Conclusions: The clinical results after LVAD implantation in DM patients were comparable with those in non-DM patients, except for the driveline exit site infection.

Background: The superiority of a fully magnetically levitated centrifugal-flow left ventricular assist device (LVAD) in terms of overall survival, stroke events and pump thrombosis has been demonstrated in previous international analyses, so we evaluated a Japanese cohort for the same.

Methods and Results: This retrospective observational study was conducted at Osaka University Medical Hospital and the National Cerebral and Cardiovascular Center in Japan. A total of 75 consecutive patients who underwent HeartMate3 (HM3) implantation were included. The primary endpoint was on-device survival, and the secondary endpoint was the incidence of LVAD-related complications at 2 years. All parameters were compared with those of the previously performed HeartMate II (HMII) implantation in 197 cases. The on-device survival rates were 94.7% and 92.3% in the HM3 and HMII groups, respectively, at the 2-year follow-up (P=0.62). The rehospitalization-free rate after implantation was 61.8% in the HM3 group, which was significantly higher than that in the HMII group (relative risk, 0.35; 95% confidence interval [CI], 0.23–0.55; P<0.0001). Event-free survival rates from cerebral cerebrovascular events and pump thrombosis in the HM3 group were significantly higher than those in the HMII group, at 97.2% and 100%, respectively (relative risk, 0.14; 95% CI 0.03–0.58); P=0.0015 and relative risk, not calculated; P=0.049, respectively).

Conclusions: Satisfactory short-term outcomes were observed after HM3 implantation in a Japanese cohort.

Background: Non-contrast T1 hypointense infarct cores (ICs) within infarcted myocardium detected using cardiac magnetic resonance imaging (CMR) T1 mapping may help assess the severity of left ventricular (LV) injury. However, because the relationship of ICs with chronic LV reverse remodeling (LVRR) is unknown, this study aimed to clarify it.

Methods and Results: We enrolled patients with reperfused AMI who underwent baseline CMR on day-7 post-primary percutaneous coronary intervention (n=109) and 12-month follow-up CMR (n=94). Correlations between ICs and chronic LVRR (end-systolic volume decrease ≥15% at 12-month follow-up from baseline CMR) were investigated. We detected 52 (47.7%) ICs on baseline CMR by non-contrast-T1 mapping. LVRR was found in 52.1% of patients with reperfused AMI at 12-month follow-up. Patients with ICs demonstrated higher peak creatine kinase levels, higher B-type natriuretic peptide levels at discharge, lower LV ejection fraction at discharge, and lower incidence of LVRR than those without ICs (26.5% vs. 73.3%, P<0.001) at follow-up. Multivariate logistic regression analysis showed that the presence of ICs was an independent and the strongest negative predictor for LVRR at 12-month follow-up (hazard ratio: 0.087, 95% confidence interval: 0.017–0.459, P=0.004). Peak creatine kinase levels, native T1 values at myocardial edema, and myocardial salvaged indices also correlated with ICs.

Conclusions: ICs detected by non-contrast-T1 mapping with 3.0-T CMR were an independent negative predictor of LVRR in patients with reperfused AMI.

Background: It is still unclear whether changes in right ventricular function are associated with prognosis in heart failure (HF) patients. This study aimed to examine the prognostic effect of changes in right ventricular fractional area change (RVFAC).

Methods and Results: This study enrolled 480 hospitalized patients with decompensated HF, and measured RVFAC with echocardiography at discharge (first examination) and post-discharge in the outpatient setting (second examination). RVFAC was divided into 3 categories: >35% in 314 patients, 25–35% in 108 patients, and <25% in 58 patients. Next, based on changes in RVFAC from the first to the second examination, the patients were further classed into 4 groups: (1) Preserved/Unchanged (preserved and unchanged RVFAC, n=235); (2) Reduced/Improved (improved RVFAC in at least 1 category, n=106); (3) Reduced/Unchanged (reduced and unchanged RVFAC, n=47); and (4) Preserved or Reduced/Worsened (deteriorated RVAFC in at least 1 category, n=92). Multivariate logistic regression analysis revealed that chronic kidney disease and anemia were the predictors of the preserved or reduced/worsened RVFAC. In the Kaplan-Meier analysis, changes in RVFAC were associated with the cardiac event rate and all-cause mortality. In the multivariable Cox proportional hazard analysis, the preserved or reduced/worsened RVFAC was an independent predictor of cardiac events and all-cause mortality.

Conclusions: Changes in RVFAC were associated with post-discharge prognosis in hospitalized heart failure patients.

Background: Balloon atrial septostomy (BAS) is an essential catheterization procedure for congenital heart lesions. Recently, a balloon catheter for static BAS was approved for the first time in Japan as an alternative to the conventional pull-through BAS. Despite the expected increase in the use of static BAS, reports on its safety are scarce worldwide.

Methods and Results: Data on static and pull-through BAS registered in a national registry between 2016 and 2018 were collected. During the study period, 247 sessions of static BAS and 588 sessions of pull-through BAS were performed on a total of 674 patients. Patients who underwent static BAS were older (P<0.001). The incidence of serious adverse events (4.3% vs. 0.9%, P=0.03) and the overall incidence of adverse events (8.1% vs. 3.2%, P=0.03) were higher in static BAS than in pull-through BAS. Among patients who underwent static BAS, the risk factor for adverse events was a body weight <3 kg at the time of the procedure (odds ratio: 4.3 [confidence interval: 1.7–11], P=0.003).

Conclusions: This nationwide study revealed differences in patient background between static and pull-through BAS, as well as a higher incidence of adverse events related to static BAS. Patients weighing <3 kg are at high risk for adverse events after static BAS and may require surgical and circulatory support backup.

Background: Few studies have comprehensively evaluated the trends and factors associated with CR participation across major cardiovascular diseases in Japan.

Methods and Results: This study performed a nationwide cross-sectional study using the National Database of Health Insurance Claims and Specific Health Checkups of Japan and the Japanese Registry of All Cardiac and Vascular Diseases and the Diagnosis Procedure Combination database. This study described the nationwide trends and evaluated patient- and hospital-level associated factors of CR participation for patients with acute heart failure (AHF), acute coronary syndrome (ACS), acute aortic dissection (AAD), peripheral artery disease (PAD), and after cardiovascular surgery using mixed-effect logistic regression analysis. Although the annual number of patients who underwent CR has increased during the study period, the total number of patients participating in outpatient CR was lower than that of inpatient CR. The outpatient CR participation rate was lower for patients with AHF (3.5%), AAD (3.2%), and PAD (1.7%), compared with ACS (7.9%) and after surgery (9.4%). Age, sex, body mass index, Barthel index, Charlson comorbidity index, and institutional capacity were identified as significant associated factors of CR participation in inpatient and outpatient settings.

Conclusions: Participation in outpatient CR was still low, and higher age, multi-comorbidity, and low institutional capacity contributed to the lower outpatient CR participation rate. Identification of the associated factors may help cardiologists to increase CR participation.

Background: Although B-type natriuretic peptide (BNP) and N-terminal (NT)-proBNP are commonly used markers of heart failure, a simple conversion formula between these peptides has not yet been developed for clinical use.

Methods and Results: A total of 9,394 samples were obtained from Nara Medical University, Jichi Medical University, and Osaka University. We randomly selected 70% for a derivation set to investigate a conversion formula from BNP to NT-proBNP using estimated glomerular filtration rate (eGFR) and body mass index (BMI); the remaining 30% was used as the internal validation set and we used a cohort study from Nara Medical University as an external validation set. Multivariate linear regression analysis revealed a new conversion formula: log NT-proBNP = 1.21 + 1.03 × log BNP − 0.009 × BMI − 0.007 × eGFR (r²=0.900, P<0.0001). The correlation coefficients between the actual and converted values of log NT-proBNP in the internal and external validation sets were 0.942 (P<0.0001) and 0.891 (P<0.0001), respectively. We applied this formula to samples obtained from patients administered with sacubitril/valsartan. After treatment initiation, NT-proBNP levels decreased and actual BNP levels increased. However, the calculated BNP levels decreased roughly parallel to the NT-proBNP levels.

Conclusions: This new and simple conversion formula of BNP and NT-proBNP with eGFR and BMI is potentially useful in clinical practice.

Background: The cost-effectiveness of sodium-glucose cotransporter 2 (SGLT2) inhibitors for chronic kidney disease (CKD) has not been evaluated in Japan, so we analyzed the cost-effectiveness of dapagliflozin, an SGLT2 inhibitor, for CKD stages 3a and 3b.

Methods and Results: We used the Markov model for CKD to assess the costs and benefits associated with and without dapagliflozin from a health system perspective. We estimated the incremental cost-effectiveness ratio (ICER), expressed as per quality-adjusted life-years (QALYs). An ICER <5 million Japanese yen (JPY)/QALY was judged to be cost-effective. The effect of dapagliflozin on renal and cardiovascular events was based on published clinical trials. In patients with CKD stage 3a, the ICER of dapagliflozin over standard treatment was 4.03 million JPY/QALY gained. With a cost-effectiveness threshold of 5 million JPY/QALY gained, the cost-effectiveness probability of dapagliflozin over standard treatment was 52.6%. In patients with CKD stage 3b, the ICER of dapagliflozin over standard treatment was 0.12 million JPY/QALY gained. The cost-effectiveness probability of dapagliflozin over standard treatment was 75.2%.

Conclusions: The results seemed to show acceptable cost-effectiveness when dapagliflozin was used for CKD stage 3b. On the other hand, cost-effectiveness of dapagliflozin for CKD stage 3a was ambiguous, and further validation is needed.

Background: Elevated central venous pressure (CVP) in heart failure causes renal congestion, which deteriorates prognosis. Sodium glucose co-transporter 2 inhibitor (SGLT2-i) improves kidney function and heart failure prognosis; however, it is unknown whether they affect renal congestion. This study investigated the effect of SGLT2-i on the kidney and left ventricle using model rats with hypertensive heart failure.

Methods and Results: Eight rats were fed a 0.3% low-salt diet (n=7), and 24 rats were fed an 8% high-salt diet, and they were divided into 3 groups of untreated (n=6), SGLT2-i (canagliflozin; n=6), and loop diuretic (furosemide; n=5) groups after 11 weeks of age. At 18 weeks of age, CVP and renal intramedullary pressure (RMP) were monitored directly by catheterization. We performed contrast-enhanced ultrasonography to evaluate intrarenal perfusion. In all high-salt fed groups, systolic blood pressure was elevated (P=0.287). The left ventricular ejection fraction did not differ among high-salt groups. Although CVP decreased in both the furosemide (P=0.032) and the canagliflozin groups (P=0.030), RMP reduction (P=0.003) and preserved renal medulla perfusion were only observed in the canagliflozin group (P=0.001). Histological analysis showed less cast formation in the intrarenal tubule (P=0.032), left ventricle fibrosis (P<0.001), and myocyte thickness (P<0.001) in the canagliflozin group than in the control group.

Conclusions: These results suggest that SGLT2-i causes renal decongestion and prevents left ventricular hypertrophy, fibrosis, and dysfunction