Shinichiro Suna

Circulating p53-Responsive MicroRNAs Are Predictive Indicators of Heart Failure After Acute Myocardial Infarction

Rationale: Despite a recent decline of in-hospital mortality attributable to acute myocardial infarction (AMI), the incidence of ischemic heart failure (HF) in post-AMI patients is increasing. Although various microRNAs have been proposed as diagnostic indicators for AMI, no microRNAs have been established as predictors of ischemic HF that develops after AMI. Objective: We attempted to identify circulating microRNAs that can serve as reliable predictors of ischemic HF in post-AMI patients. Methods and Results: Using sera collected a median of 18 days after AMI onset, we screened microRNAs in 21 patients who experienced development of HF within 1 year after AMI and in 65 matched controls without subsequent cardiovascular events after discharge. Among the 377 examined microRNAs, the serum level of only miR-192 was significantly upregulated in AMI patients with development of ischemic HF. Because miR-192 is reported to be p53-responsive, the serum levels of 2 other p53-responsive microRNAs, miR-194 and miR-34a, also were investigated. Interestingly, both microRNAs were coordinately increased with miR-192, particularly in exosomes, suggesting that these microRNAs function as circulating regulators of HF development via the p53 pathway. Furthermore, miR-194 and miR-34a expression levels were significantly correlated with left ventricular end-diastolic dimension 1 year after AMI. Conclusions: In the sera of post-AMI patients who experienced development of de-novo HF within 1 year of AMI onset, the levels of 3 p53-responsive microRNAs had been elevated by the early convalescent stage of AMI. Further investigations are warranted to confirm the usefulness of these circulating microRNAs for predicting the risk of development of ischemic HF after AMI.

A subset of circulating microRNAs are predictive for cardiac death after discharge for acute myocardial infarction

To investigate the prognostic impact of circulating microRNAs (miRs) in patients who survived acute myocardial infarction (AMI), we compared the circulating miR signature at the time of survival discharge among samples in the serum bank of the Osaka Acute Coronary Insufficiency Study. Using a high-throughput array consisting of 667 miRs, 11 miRs were found to be differentially expressed in the serum among patients at high-risk for cardiac death. Real-time RT-PCR confirmed that the serum levels of miR-155 and miR-380* were approximately 4- and 3-fold higher, respectively, in patients who experienced cardiac death within 1 year after discharge. Accordingly, a subset of circulating miRs might be predictive for cardiac death in post-AMI patients.

A genome-wide association study identifies PLCL2 and AP3D1-DOT1L-SF3A2 as new susceptibility loci for myocardial infarction in Japanese

Despite considerable progress in preventive and therapeutic strategies, myocardial infarction (MI) is one of the leading causes of death throughout the world. A total of 55 susceptibility genes have been identified mostly in European genome-wide association studies (GWAS). Nevertheless, large-scale GWAS from other population could possibly find additional susceptibility loci. To identify as many MI susceptibility loci as possible, we performed a large-scale genomic analysis in Japanese population. To identify MI susceptibility loci in Japanese, we conducted a GWAS using 1666 cases and 3198 controls using the Illumina Human610-Quad BeadChip and HumanHap550v3 Genotyping BeadChip. We performed replication studies using a total of 11 412 cases and 28 397 controls in the Japanese population. Our study identified two novel susceptibility loci for MI: PLCL2 on chromosome 3p24.3 (rs4618210:A>G, P=2.60 × 10−9, odds ratio (OR)=0.91) and AP3D1-DOT1L-SF3A2 on chromosome 19p13.3 (rs3803915:A>C, P=3.84 × 10−9, OR=0.89). Besides, a total of 14 previously reported MI susceptibility loci were replicated in our study. In particular, we validated a strong association on chromosome 12q24 (rs3782886:A>G: P=1.14 × 10−14, OR=1.46). Following pathway analysis using 265 genes related to MI or coronary artery disease, we found that these loci might be involved in the pathogenesis of MI via the promotion of atherosclerosis. In the present large-scale genomic analysis, we identified PLCL2 and AP3D1-DOT1L-SF3A2 as new susceptibility loci for MI in the Japanese population. Our findings will add novel findings for MI susceptibility loci.

Living alone and risk of cardiovascular events following discharge after acute myocardial infarction in Japan

BACKGROUND Little is known about the long-term risk of cardiovascular events after discharge among acute myocardial infarction (AMI) survivors living alone in Japan. METHODS AND RESULTS A large-scale prospective, observational study in the Osaka region involved consecutive patients with AMI from January 2002 through December 2010. We evaluated the association between living alone and longitudinal risk of cardiovascular events following discharge after AMI. A Cox proportional-hazards model was used to assess the association between living alone and the primary composite endpoint consisting of major adverse cardiovascular events and total deaths. During the study period, 5845 patients (4415 male patients, 1430 female patients) were registered. Living alone was found to be independently associated with a higher risk of composite endpoint consisting of major adverse cardiovascular events and total deaths [adjusted hazard ratio (HR) 1.32; 95% confidence interval (CI): 1.11-1.58]. Multivariate-adjusted HRs of composite endpoint were 1.34 (95% CI: 1.08-1.68) among male patients and 1.31 (95% CI: 0.95-1.81) in the female patients. AMI survivors living alone tend to have a higher adjusted HR of composite endpoint than those not living alone irrespective of age and gender groups. CONCLUSIONS From this large AMI registry in Osaka, AMI survivors living alone after discharge had a higher risk of cardiovascular events and total deaths than those not living alone.

Oral treatment with nicorandil at discharge is associated with reduced mortality after acute myocardial infarction.

BACKGROUND Previous studies showed that nicorandil can reduce coronary events in patients with coronary artery disease. However, it is unclear whether oral nicorandil treatment may reduce mortality following acute myocardial infarction (AMI). METHODS AND RESULTS We examined the impact of oral nicorandil treatment on cardiovascular events in 1846 AMI patients who were hospitalized within 24 h after AMI onset, treated with emergency percutaneous coronary intervention (PCI), and discharged alive. Patients were divided into those with (Group N, n=535) and without (Group C, n=1311) oral nicorandil treatment at discharge. No significant differences in age, gender, body mass index, prevalence of coronary risk factors, or history of myocardial infarction existed between the two groups; however, higher incidences of multi-vessel disease, and a lower rate of successful PCI were observed in Group N. During the median follow-up of 709 (340-1088) days, all-cause mortality rate was 43% lower in Group N compared with Group C (2.4% vs. 4.2%, stratified log-rank test: p=0.0358). Multivariate Cox regression analysis revealed that nicorandil treatment was associated with all-cause death after discharge (Hazard ratio 0.495, 95% CI: 0.254-0.966, p=0.0393), but not for other cardiovascular events such as re-infarction, admission for heart failure, stroke and arrhythmia. CONCLUSIONS The results suggest that oral administration of nicorandil is associated with reduced incidence of death in the setting of secondary prevention after AMI.

Subclinical elevation of high-sensitive troponin T levels at the convalescent stage is associated with increased 5-year mortality after ST-elevation myocardial infarction

BACKGROUND It is unclear whether serum high-sensitive troponin T (hs-TnT) levels at the convalescent stage of ST-elevation myocardial infarction (STEMI) are associated with long-term mortality. METHODS This study enrolled a total of 2944 consecutive STEMI patients who were registered in the Osaka Acute Coronary Insufficiency Study between 2000 and 2009, and whose hs-TnT levels were evaluated at the convalescent stage. Patients were divided into four hs-TnT category groups according to the results of survival classification and regression tree (CART) analysis. The impact of hs-TnT levels on 5-year mortality was evaluated using multivariate Cox regression analysis. RESULTS Only one patient had hs-TnT level below the detection limit of the assay (<0.003ng/mL). The median hs-TnT level was 0.025 (quartile 0.011-0.083)ng/mL. During the median follow-up period of 1782 days, 188 patients died. Survival CART analysis revealed that the 1st, 2nd, and 3rd discriminating hs-TnT levels to discern 5-year mortality were 0.028, 0.008, and 1.340ng/mL, respectively. The adjusted hazard ratios for the medium-low (0.009-0.028ng/mL), medium-high (0.029-1.340ng/mL), and high-risk (≥1.341ng/mL) groups were 3.03 (95% confidence interval 1.18-7.77, p=0.021), 4.29 (1.63-11.28, p=0.003), and 8.68 (2.20-34.27, p=0.002), respectively. Integrated discrimination improvement (IDI) analysis revealed that incorporation of this hs-TnT classification scheme with other clinical variables statistically improved the discriminatory accuracy for 5-year mortality, with a time-dependent IDI of 0.0076 (p=0.033). CONCLUSIONS hs-TnT levels at the convalescent stage were associated with long-term mortality in STEMI patients. Even subclinical elevation of hs-TnT levels was associated with increased 5-year mortality.

Clinical impact of acute hyperglycemia on development of diabetes mellitus in non-diabetic patients with acute myocardial infarction

BACKGROUND Acute hyperglycemia (AH) after the onset of acute myocardial infarction (AMI) is a manifestation of transient abnormal glucose metabolism that may reflect AMI severity, and thus be a predictor of poor prognosis. However, it remains unknown whether AH may predict development of de novo diabetes mellitus (dn-DM) in non-diabetic AMI patients. METHODS AND RESULTS Among AMI patients registered in the Osaka Acute Coronary Insufficiency Study between 1998 and 2007, we investigated hospital records of 1493 patients who had an admission glycated hemoglobin A1c (HbA1c) level of ≤6.0% and were subjected to glycometabolic profiling after survival discharge. dn-DM was defined as initiation of diabetic medication or documentation of an HbA1c level of ≥6.5% during the 5-year follow-up period. AH, defined as an admission serum glucose level of ≥200mg/dl, was observed in 133 (8.9%) patients. dn-DM development was more frequent in post-AMI patients with AH than those without [24.8% vs 12.0%, adjusted hazard ratio (HR) 1.776, p=0.021], particularly among patients with an HbA1c of <5.6% on admission. Treatment with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers was associated with a reduced incidence of dn-DM in patients with AH (adjusted HR 0.397, p=0.031). CONCLUSION Admission AH was a predictor of dn-DM in non-diabetic post-AMI patients. Renin-angiotensin system inhibitors were associated with reduced incidence of dn-DM in post-AMI patients with AH.

Clinical Impact of Ventricular Tachycardia and/or Fibrillation During the Acute Phase of Acute Myocardial Infarction on In-Hospital and 5-Year Mortality Rates in the Percutaneous Coronary Intervention Era

BACKGROUND The aim of this study was to investigate the prognostic impact of acute-phase ventricular tachycardia and fibrillation (VT/VF) on ST-segment elevation myocardial infarction (STEMI) patients in the percutaneous coronary intervention (PCI) era. METHODSANDRESULTS Using the database of the Osaka Acute Coronary Insufficiency Study (OACIS), we studied 4,283 consecutive patients with STEMI who were hospitalized within 12 h of STEMI onset and underwent emergency PCI. Acute-phase VT/VF, defined as ≥3 consecutive ventricular premature complexes and/or VF within the 1st week of hospitalization, occurred in 997 (23.3%) patients. In-hospital mortality risk was significantly higher in patients with acute-phase VT/VF than inthose without (14.6% vs. 4.3%, adjusted hazard ratio (HR) 1.83, P=0.0013). Among patients discharged alive, 5-year mortality rates were comparable between patients with and without acute-phase VT/VF. Subgroup analysis showed that acute-phase VT/VF was associated with increased 5-year mortality after discharge in high-risk patients (GRACE Risk Score ≥115; adjusted HR 1.60, P=0.043), but not in intermediate- or low-risk patients. CONCLUSIONS Even in the PCI era, acute-phase VT/VF was associated with higher in-hospital deaths of STEMI patients. However, the 5-year prognostic impact of acute-phase VT/VF was limited to high-risk patients. (Circ J 2016; 80: 1539-1547).

A functional SNP in FLT1 increases risk of coronary artery disease in a Japanese population.

Coronary artery disease (CAD) including myocardial infarction is one of the leading causes of death in many countries. Similar to other common diseases, its pathogenesis is thought to result from complex interactions among multiple genetic and environmental factors. Recent large-scale genetic association analysis for CAD identified 15 new loci. We examined the reproducibility of these previous association findings with 7990 cases and 6582 controls in a Japanese population. We found a convincing association of rs9319428 in FLT1, encoding fms-related tyrosine kinase 1 (P=5.98 × 10−8). Fine mapping using tag single-nucleotide polymorphisms (SNPs) at FLT1 locus revealed that another SNP (rs74412485) showed more profound genetic effect for CAD (P=2.85 × 10−12). The SNP, located in intron 1 in FLT1, enhanced the transcriptional level of FLT1. RNA interference experiment against FLT1 showed that the suppression of FLT1 resulted in decreased expression of inflammatory adhesion molecules. Expression of FLT1 was observed in endothelial cells of human coronary artery. Our results indicate that the genetically coded increased expression of FLT1 by a functional SNP implicates activation in an inflammatory cascade that might eventually lead to CAD.

Effect of intracoronary thrombectomy on 30-day mortality in non-diabetic patients with acute hyperglycemia after acute myocardial infarction

BACKGROUND There is limited evidence about useful therapeutic interventions for patients with acute hyperglycemia (AH) after acute myocardial infarction (AMI). METHODS We studied 2433 consecutive non-diabetic AMI patients who underwent percutaneous coronary intervention (PCI) within 24h after the onset. Patients were divided into two groups according to the presence or absence of AH (admission serum glucose level ≥ 11.1 mmol/l). We assessed the association between intracoronary thrombectomy and the clinical outcome in AMI patients with AH. RESULTS Patients with AH had more risk factors than those without AH. The 30-day mortality rate of patients with AH was significantly higher than that of those without (11.7% vs 1.7%, p<0.001). Among patients with AH, the 30-day mortality rate was significantly lower for those with intracoronary thrombectomy than those without it (4.9% vs 17.2%, p=0.004). Among patients without AH, however, the 30-day mortality rate was similar between those with and without intracoronary thrombectomy (1.5% vs 1.9%, p=NS). Multivariate analysis showed that intracoronary thrombectomy was associated with an improved 30-day mortality rate for patients with AH (hazard ratio: HR 0.184, 95% CI 0.057-0.598, p=0.005). CONCLUSIONS In AMI patients with AH, intracoronary thrombectomy prior to PCI might improve the 30-day mortality rate.