Sanae Hamaguchi

Oxidative stress in skeletal muscle impairs mitochondrial respiration and limits exercise capacity in type 2 diabetic mice

Insulin resistance or diabetes is associated with limited exercise capacity, which can be caused by the abnormal energy metabolism in skeletal muscle. Oxidative stress is involved in mitochondrial dysfunction in diabetes. We hypothesized that increased oxidative stress could cause mitochondrial dysfunction in skeletal muscle and make contribution to exercise intolerance in diabetes. C57/BL6J mice were fed on normal diet or high fat diet (HFD) for 8 wk to induce obesity with insulin resistance and diabetes. Treadmill tests with expired gas analysis were performed to determine the exercise capacity and whole body oxygen uptake (Vo(2)). The work (vertical distance x body weight) to exhaustion was reduced in the HFD mice by 36%, accompanied by a 16% decrease of peak Vo(2). Mitochondrial ADP-stimulated respiration, electron transport chain complex I and III activities, and mitochondrial content in skeletal muscle were decreased in the HFD mice. Furthermore, superoxide production and NAD(P)H oxidase activity in skeletal muscle were significantly increased in the HFD mice. Intriguingly, the treatment of HFD-fed mice with apocynin [10 mmol/l; an inhibitor of NAD(P)H oxidase activation] improved exercise intolerance and mitochondrial dysfunction in skeletal muscle without affecting glucose metabolism itself. The exercise capacity and mitochondrial function in skeletal muscle were impaired in type 2 diabetes, which might be due to enhanced oxidative stress. Therapies designed to regulate oxidative stress and maintain mitochondrial function could be beneficial to improve the exercise capacity in type 2 diabetes.

Angiotensin II type 1 receptor blocker attenuates myocardial remodeling and preserves diastolic function in diabetic heart

Blockade of the renin-angiotensin system reduces cardiovascular morbidity and mortality in diabetic patients. Angiotensin II (Ang II) plays an important role in the structural and functional abnormalities of the diabetic heart. We investigated whether or not Ang II type 1 receptor blocker (ARB) could attenuate left ventricular (LV) remodeling in male mice with diabetes mellitus (DM) induced by the injection of streptozotocin (200 mg/kg, i.p.). Diabetic mice were treated with candesartan (1 mg/kg/day; DM+Candesartan, n=7) or vehicle (DM+Vehicle, n=7) for 8 weeks. Heart rate and aortic blood pressure were comparable between the groups. Normal systolic function was preserved in diabetic mice. In contrast, diastolic function was impaired in DM+Vehicle and was improved in DM+Candesartan, as assessed by the deceleration time of the peak velocity of transmitral diastolic flow (40.3±0.3 vs. 37.3±0.5 ms, p<0.01) and the time needed for relaxation of 50% maximal LV pressure to baseline value (τ; 10.6±0.7 vs. 8.7±0.6 ms, p<0.05) without significant changes in heart rate and aortic blood pressure. Improvement of LV diastolic function was accompanied by the attenuation of myocyte hypertrophy, interstitial fibrosis and apoptosis in association with the expression of connective tissue growth factor (CTGF) and myocardial oxidative stress. Moreover, candesartan directly inhibited Ang II–mediated induction of CTGF in cultured cardiac fibroblasts. ARB might be beneficial to prevent cardiac abnormalities in DM.

Hyperuricemia predicts adverse outcomes in patients with heart failure.

BACKGROUND Hyperuricemia is associated with worse outcomes of patients with chronic heart failure (HF). However, it is unknown in an unselected HF patients encountered in routine clinical practice. We thus assessed the impact of hyperuricemia on long-term outcomes including mortality and rehospitalization among patients hospitalized with worsening HF. METHODS The Japanese Cardiac Registry of Heart Failure in Cardiology (JCARE-CARD) studied prospectively the characteristics and treatments in a broad sample of hospitalized HF patients and the outcomes were followed for 2.1 years after discharge. Study cohorts (n=1869) were divided into 2 groups according to serum uric acid (UA) at discharge; ≥ 7.4 mg/dL (n=908) and <7.4 mg/dL (n=961). RESULTS Of the total cohort of HF patients, 56% had hyperuricemia defined as UA ≥ 7.0mg/dl. Patients with UA ≥ 7.4 mg/dL had higher rates of all-cause death, cardiac death, rehospitalization, and all-cause death or rehospitalization due to worsening HF. After multivariable adjustment, higher UA levels were a significant and independent predictor for all-cause death (adjusted hazard ratio [HR] 1.413, 95% confidence interval [CI] 1.094-1.824, P=0.008) and cardiac death (adjusted HR 1.399, 95% CI 1.020-1.920, P=0.037). CONCLUSIONS Hyperuricemia was common in patients with HF encountered in clinical practice and higher UA was independently associated with long-term adverse outcomes in these patients.

Spironolactone use at discharge was associated with improved survival in hospitalized patients with systolic heart failure

BACKGROUND The RALES trial demonstrated that spironolactone improved the prognosis of patients with heart failure (HF). However, it is unknown whether the discharge use of spironolactone is associated with better long-term outcomes among hospitalized systolic HF patients in routine clinical practice. We examined the effects of spironolactone use at discharge on mortality and rehospitalization by comparing with outcomes in patients who did not receive spironolactone. METHODS The JCARE-CARD studied prospectively the characteristics and treatments in a broad sample of patients hospitalized with worsening HF and the outcomes were followed with an average of 2.2 years of follow-up. RESULTS A total of 946 patients had HF with reduced left ventricular ejection fraction (LVEF) (<40%), among whom spironolactone was prescribed at discharge in 435 patients (46%), but not in 511 patients (54%). The mean age was 66.3 years and 72.2% were male. Etiology was ischemic in 39.7% and mean LVEF was 27.1%. After adjustment for covariates, discharge use of spironolactone was associated with a significant reduction in all-cause death (adjusted hazard ratio 0.612, P=.020) and cardiac death (adjusted hazard ratio 0.524, P=.013). CONCLUSIONS Among patients with HF hospitalized for systolic dysfunction, spironolactone use at the time of discharge was associated with long-term survival benefit. These findings provide further support for the idea that spironolactone may be useful in patients hospitalized with HF and reduced LVEF.

Increased myocardial NAD(P)H oxidase-derived superoxide causes the exacerbation of postinfarct heart failure in type 2 diabetes

Type 2 diabetes adversely affects the outcomes in patients with myocardial infarction (MI), which is associated with the development of left ventricular (LV) failure. NAD(P)H oxidase-derived superoxide (O(2)(-)) production is increased in type 2 diabetes. However, its pathophysiological significance in advanced post-MI LV failure associated with type 2 diabetes remains unestablished. We thus hypothesized that an inhibitor of NAD(P)H oxidase activation, apocynin, could attenuate the exacerbated LV failure after MI in high-fat diet (HFD)-induced obese mice with type 2 diabetes. Male C57BL/6J mice were fed on either HFD or normal diet (ND) for 8 wk. At 4 wk of feeding, MI was created in mice by ligating the left coronary artery. HFD-fed MI mice were treated with either 10 mmol/l apocynin or vehicle. HFD + MI had significantly greater LV end-diastolic diameter (LVEDD; 5.7 +/- 0.1 vs. 5.3 +/- 0.2 mm), end-diastolic pressure (12 +/- 2 vs. 8 +/- 1 mmHg), and lung weight/tibial length (10.1 +/- 0.3 vs. 8.7 +/- 0.7 mg/mm) than ND + MI, which was accompanied by an increased interstitial fibrosis of noninfarcted LV. Treatment of HFD + MI with apocynin significantly decreased LVEDD (5.4 +/- 0.1 mm), LV end-diastolic pressure (9.7 +/- 0.8 mmHg), lung weight/tibial length (9.0 +/- 0.3 mg/mm), and concomitantly interstitial fibrosis of noninfarcted LV to the ND + MI level without affecting body weight, glucose metabolism, and infarct size. NAD(P)H oxidase activity and O(2)(-) production were increased in noninfarcted LV tissues from HFD + MI, both of which were attenuated by apocynin to the ND + MI level. Type 2 diabetes was associated with the exacerbation of LV failure after MI via increasing NAD(P)H oxidase-derived O(2)(-), which may be a novel important therapeutic target in advanced heart failure with diabetes.

Characteristics, management, and outcomes for patients during hospitalization due to worsening heart failure—A report from the Japanese Cardiac Registry of Heart Failure in Cardiology (JCARE-CARD)

BACKGROUND The characteristics, in-hospital management, and outcomes of patients hospitalized with worsening heart failure (HF) have been described by large-scale registries performed mainly in the USA and Europe. However, little information is available in Japan. We thus clarified the characteristics and clinical status as well as in-hospital management and outcomes among patients hospitalized with worsening HF in Japan and compared them with those reported in previous studies. METHODS The Japanese Cardiac Registry of Heart Failure in Cardiology (JCARE-CARD) studied prospectively the characteristics and treatments in patients hospitalized with worsening HF. From the total cohort of JCARE-CARD, 1677 patients were randomly selected and their detailed data during acute phase were collected as another registry database in the present study. The characteristics, in-hospital management, and outcomes were analyzed. RESULTS The mean age was 70.7 years and 59.4% were male. Etiology was ischemic in 34.0% and mean left ventricular ejection fraction was 42.5%. Carperitide was highly used as in-hospital management in Japan (33.5%) compared to the use of nesiritide in the USA (8-11%). The use of angiotensin-converting enzyme inhibitors was lower and angiotensin II receptor blockers (ARB) were more commonly used in this study compared to other studies in the USA and Europe. In-hospital crude mortality rate was comparable among studies (4-8%), however, length of stay was longer in Japan (15-20 versus 4-9 days). CONCLUSIONS The characteristics, clinical status, and laboratory data on admission in patients hospitalized with worsening HF were similar between the present study and previous Japanese and western studies. Management was also similar except for higher use of carperitide and ARB. The most striking difference between Japanese registries and those from the USA and Europe was the longer length of stay.

Hyponatremia is an independent predictor of adverse clinical outcomes in hospitalized patients due to worsening heart failure

BACKGROUND AND PURPOSE Hyponatremia is common and is associated with poor in-hospital outcomes in patients hospitalized with heart failure (HF). However, it is unknown whether hyponatremia is associated with long-term adverse outcomes. The purpose of this study was to clarify the characteristics, clinical status on admission, and management during hospitalization according to the serum sodium concentration on admission, and determine whether hyponatremia was associated with in-hospital as well as long-term outcomes in 1677 patients hospitalized with worsening HF on index hospitalization registered in the database of the Japanese Cardiac Registry of Heart Failure in Cardiology (JCARE-CARD). METHODS AND SUBJECTS We studied the characteristics and in-hospital treatment in 1659 patients hospitalized with worsening HF by using the JCARE-CARD database. Patients were divided into 2 groups according to serum sodium concentration on admission <135mEq/mL (n=176; 10.6%) or ≥135mEq/mL (n=1483; 89.4%). RESULTS The mean age was 70.7 years and 59.2% were male. Etiology was ischemic in 33.9% and mean left ventricular ejection fraction was 42.4%. After adjustment for covariates, hyponatremia was independently associated with in-hospital death [adjusted odds ratio (OR) 2.453, 95% confidence interval (CI) 1.265-4.755, p=0.008]. It was significantly associated also with adverse long-term (mean 2.1±0.8 years) outcomes including all-cause death (OR 1.952, 95% CI 1.433-2.657), cardiac death (OR 2.053, 95% CI 1.413-2.983), and rehospitalization due to worsening HF (OR 1.488, 95% CI 1.134-1.953). CONCLUSIONS Hyponatremia was independently associated with not only in-hospital but also long-term adverse outcomes in patients hospitalized with worsening HF.

Discharge use of angiotensin receptor blockers provides comparable effects with angiotensin-converting enzyme inhibitors on outcomes in patients hospitalized for heart failure

Large-scale, placebo-controlled, randomized clinical trials have shown that angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) reduce mortality and hospitalization in patients with heart failure (HF) caused by left ventricular systolic dysfunction (LVSD). However, it is unknown whether ACE inhibitors and ARBs have similar effects on the long-term outcomes in HF patients encountered in routine clinical practice. The Japanese Cardiac Registry of Heart Failure in Cardiology enrolled HF patients hospitalized with worsening symptoms and they were followed during an average of 2.2 years. The outcome data were compared in patients with LVSD by echocardiography (ejection fraction, EF <40%) according to the predischarge use of ACE inhibitors (n=356) or ARBs (n=372). The clinical characteristics were similar between patients with ACE inhibitor and ARB use, except for higher prevalence of hypertensive etiology and diabetes mellitus. There was no significant difference between ACE inhibitor and ARB use in all-cause death (adjusted hazard ratio 0.958, 95% confidence interval 0.601–1.527, P=0.858) and rehospitalization (adjusted hazard ratio 0.964, 95% confidence interval 0.683–1.362, P=0.836). The effects of ACE inhibitor and ARB use on the outcomes were generally consistent across all clinically relevant subgroups examined, including age, sex, etiology, EF, hypertension, diabetes mellitus, and β-blocker use. Discharge use of ARBs provided comparable effects with ACE inhibitors on outcomes in patients hospitalized for HF. These findings provide further support for guideline recommendations that ARBs can be used in patients with HF and LVSD as an alternative of ACE inhibitors.

Weekend versus weekday hospital admission and outcomes during hospitalization for patients due to worsening heart failure: a report from Japanese Cardiac Registry of Heart Failure in Cardiology (JCARE-CARD)

The day of the week of admission may influence the length of stay and in-hospital death. However, the association between the admission day of the week and in-hospital outcomes has been inconsistent in heart failure (HF) patients among studies reported from Western countries. We thus analyzed this association in HF patients encountered in routine clinical practice in Japan. We studied the characteristics and in-hospital treatment in 1620 patients hospitalized with worsening HF by using the database of the Japanese Cardiac Registry of Heart Failure in Cardiology (JCARE-CARD). Patients were divided into two groups according to weekday (n = 1355; 83.6 %) or weekend admission (n = 265; 16.4 %). The mean age was 70.7 years and 59.4 % were male. Etiology was ischemic in 34.0 %, and mean left ventricular ejection fraction was 42.5 %. Patients admitted on the weekend were significantly older and had more comorbidities, and more severe symptoms and signs of HF on admission. Length of stay was comparable between weekend and weekday admission (35.2 ± 47.0 days vs 33.6 ± 32.0 days, P = 0.591). Crude in-hospital mortality did not differ between patients admitted on the weekend and weekdays (7.5 % vs 5.2 %, P = 0.136). Even after adjustment for covariates in multivariable modeling with patients admitted on weekday as the reference, in-hospital death was comparable between patients admitted on the weekend and weekdays (adjusted odds ratio 1.125, 95 % confidence interval 0.631–2.004, P = 0.691). Among patients hospitalized for worsening HF, admission day of the week did not affect in-hospital death and length of stay.

Sex differences with respect to clinical characteristics, treatment, and long-term outcomes in patients with heart failure

The effect of sex on the etiology, risk factors, comorbidities, treatment and prognosis in patients with heart failure (HF) encountered in routine clinical practice in Asian populations has not been well described. The objective of the present study was to elucidate sex differences with respect to the clinical characteristics, treatment, and prognosis of HF patients treated in routine clinical practice settings using the Japanese Cardiac Registry of Heart Failure in Cardiology (JCARE-CARD) database, which is a nationwide registry for hospitalized patients with HF in Japan. JCARE-CARD enrolled 2675 patients hospitalized for HF at 164 participating hospitals from January 2005 to June 2006. HF was diagnosed by the simultaneous presence of at least two major criteria or onemajor criterion in conjunctionwith twominor criteria by use of the criteria from the Framingham Heart Study [1]. For each patient, baseline data recorded on the form were: demography; HF causes; comorbidities; complications; clinical status; echocardiographic findings; plasma B-type natriuretic peptide (BNP); and treatments. Longterm follow-up data could be obtained from 2305 patients after hospital discharged. Mean post-discharge follow-up was 2.3±0.7 years.