Methods and Results— In total, 111 patients (109 men and 2 women) received a 1-hour infusion of 5, 10, and 15 mg SLV320, an adenosine A1 receptor antagonist, placebo, or 40 mg furosemide. Mean age was 57.9 years, mean ejection fraction was 28.1%, 82 patients were of New York Heart Association class II, and 29 patients were of New York Heart Association class III. Hemodynamic parameters (heart rate, blood pressure, pulmonary capillary wedge pressure, mean pulmonary arterial pressure, systemic vascular resistance, right atrial pressure, and cardiac output) were determined. Kidney function was assessed by cystatin C measurements and by analysis of urine output and urine electrolytes. In addition, pharmacokinetics of SLV320 and ex vivo inhibition of adenosine A1 receptor activity were performed. SLV320 was well tolerated, and no serious adverse events were observed. Heart rate, blood pressure, pulmonary capillary wedge pressure, mean pulmonary arterial pressure, right atrial pressure, and cardiac output were not altered by any dose of SLV320. Pulmonary capillary wedge pressure was significantly (P=0.04) decreased by furosemide (–6.2±5.9 mm Hg). Systemic vascular resistance was significantly (P=0.04) increased in the furosemide group (+166.70±261.87 dynes · s^–1 · cm^–5), whereas all SLV320 groups showed no significant alterations of systemic vascular resistance. Changes from baseline cystatin C plasma concentrations decreased after 10 mg SLV320 (–0.093±0.137 mg/L, P=0.046), whereas furosemide resulted in a significant (P=0.03) increase of cystatin C (+0.052±0.065 mg/L) versus baseline. All values represent mean changes±SD from baseline at 3 hours postdosing: SLV320 (10 and 15 mg) increased significantly sodium excretion and diuresis compared with placebo during the 0- to 6-hour collection period postdosing.

Conclusions— SLV320 infusion shows no immediate effects on cardiac hemodynamics. SLV320 might improve glomerular filtration rate while simultaneously promoting natriuresis and diuresis.

Clinical Trial Registration— clinicaltrials.gov Indentifier: NCT00160134.

Methods and Results— Ucn2 and furosemide were administered for 3 hours, both singly and combined, in 7 sheep with pacing-induced heart failure. Compared with time-matched controls, separate Ucn2 and furosemide administration significantly increased urine output (furosemide>Ucn2), urine sodium (furosemide>Ucn2), potassium (furosemide>Ucn2), and creatinine excretion (Ucn2>furosemide) and creatinine clearance (Ucn2>furosemide). Compared with furosemide treatment alone, Ucn2+furosemide produced a further diuresis (P<0.05), natriuresis (P<0.05), and a sustained increase in creatinine excretion (P<0.05) and clearance (P<0.05), without additional potassium elimination. All active treatments reduced mean arterial pressure (Ucn2+furosemide=furosemide>Ucn2), left atrial pressure (Ucn2+furosemide>Ucn2>furosemide), and peripheral resistance (Ucn2+furosemide=Ucn2>furosemide), whereas only Ucn2, singly and in combination with furosemide, increased cardiac output and dP/dt(max). In contrast to the increase in plasma renin activity elicited by furosemide alone, Ucn2 and Ucn2+furosemide markedly reduced plasma renin activity. All active treatments decreased plasma aldosterone (Ucn2+furosemide=Ucn2>furosemide), whereas only Ucn2 and Ucn2+furosemide reduced vasopressin and natriuretic peptide concentrations.

Conclusion— Ucn2 cotreatment with furosemide enhanced hemodynamic and renal function and diuretic responsiveness (without additional potassium depletion) in experimental heart failure. Furthermore, Ucn2 reversed furosemide-induced increases in plasma renin activity and induced greater decreases in plasma aldosterone and vasopressin. These data indicate that adjunct Ucn2 therapy with diuretics in heart failure is beneficial.

Methods and Results— This is a retrospective study of 354 subjects in the African American Heart Failure Trial Genetic Risk Assessment in Heart Failure substudy. In the corin variant group (n=50) compared with corin nonvariant group (n=300), BNP-32 (amino acids 77 to 108) was lower (190 pg/mL versus 340 pg/mL, P=0.007), but the ratio of unprocessed BNP_{1 to 108}/processed BNP-32 was significantly higher (P=0.05). Stratified analyses were conducted because of evidence of significant interaction between the corin I555(P568) allele and treatment assignment. In the placebo arm, multivariable analysis demonstrated that the corin I555(P568) allele was associated with increased risk for death or heart failure hospitalization (relative risk 3.49; 95% CI, 1.45 to 8.39; P=0.005); however, in the treatment arm (fixed-dose combination isosorbide-dinitrate/hydralazine), the corin I555(P568) allele was not associated with adverse outcomes.

Conclusions— We have identified a pharmacogenomic interaction in blacks with systolic heart failure. The corin I555(P568) allele is associated with an increased risk for death or heart failure hospitalization in patients receiving standard neurohormonal blockade, but the addition of fixed-dose combination isosorbide-dinitrate/hydralazine ameliorates this risk. A plausible mechanism for this pharmacogenomic interaction is the impaired processing of BNP in carriers of the corin I555(P568) allele as compared with noncarriers.

Methods and Results— Two hundred fifty-three patients diagnosed with systolic (n=211) or diastolic (n=42) HF (age: 61.9±10.1 years; New York Heart Association Class: 2.2±0.78) underwent a 6MWT and a symptom-limited CPET evaluation and were prospectively followed up. During the 4-year tracking period, there were 43 cardiac-related deaths with an annual cardiac mortality rate of 8.7%. The 6MWT distance correlated with CPET-derived variables (ie, peak Vo₂, Vo₂ at anaerobic threshold, and Ve/Vco₂ slope) and was significantly reduced in proportion with lower peak Vo₂ and higher Ve/Vco₂ slope classes and presence of an exercise oscillatory breathing (EOB) pattern (P<0.01). However, no significant differences were observed in distance covered between survivors and nonsurvivors (353.2±95.8 m versus 338.5±76.4 m; P=NS). At univariate and multivariate Cox proportional analyses, the association of the 6MWT distance with survival was not significant either as a continuous or dicotomized variable (≤300 m). Conversely, CPET-derived variables emerged as prognostic with the strongest association found for EOB (systolic HF) and Ve/Vco₂ slope (entire population with HF and patients with a 6MWT≤300 m).

Conclusions— The 6MWT is confirmed to be a simple and reliable first-line test for quantification of exercise intolerance in patients with HF. However, there is no supportive evidence for its use as a prognostic marker in alternative to or in conjunction with CPET-derived variables.

Methods and Results— We prospectively analyzed the relationship between serum uric acid concentration at baseline and subsequent heart failure among the participants of the Framingham Offspring cohort (n=4912; mean baseline age, 36 years; 52% women). By using Cox regressions, we calculated the risk of heart failure with increasing serum uric acid after adjusting for sex, age, smoking, body mass index, renal dysfunction, diuretics, systolic blood pressure, valvular heart disease, diabetes, alcohol, and use of antihypertensive medications. The incidence rates of heart failure were 6-fold higher among those at the highest quartile of serum uric acid (>6.3 mg/dL) compared with those at the lowest quartile (<3.4 mg/dL). The adjusted hazard ratio for the highest quartile of serum uric acid compared with the lowest was 2.1 (1.04 to 4.22). The relationship between hyperuricemia and heart failure was found in participants without metabolic syndrome and other subgroups as well.

Conclusions— Hyperuricemia is a novel, independent risk factor for heart failure in a group of young general community dwellers. This has implications for development of preventive strategies for heart failure.

Methods and Results— Consecutive subjects with heart failure of any cause and severity were enrolled (n=867), and survivors were followed for a median period of 594 days (25th to 75th percentile, 435 to 840). Mean age was 70±13 years, 41% were female, New York Heart Association class distribution I through IV was 15%/29%/41%/15%, and 49% had preserved left ventricular ejection function. At follow-up, 34% of the patients had died. Low levels of any risk factor (ie, body mass index, total cholesterol, and systolic blood pressure in the low tertile) indicated the highest mortality risk. After adjustment for age, sex, New York Heart Association class, and ejection fraction, ≥2 risk factors in the high tertile indicated a relative reduction in mortality risk of 51% (hazard ratio, 0.49; 95% CI, 0.35 to 0.68; P=0.001) compared with subjects with 3 risk factors in the low tertile. Further adjustment for cause of heart failure, relevant comorbidities, medication, and biomarkers attenuated this association only modestly (hazard ratio, 0.63; 95% CI, 0.45 to 0.89; P=0.009).

Conclusion— In patients with heart failure, mortality risk counterintuitively increased on a cumulative scale with lower levels of body mass index, total cholesterol, and systolic blood pressure, irrespective of the type and severity of heart failure. Future studies need to identify whether risk factor control as presently recommended should be advocated in all patients with heart failure.

Methods and Results— We identified 13 063 adult patients with acute heart failure who had cardiac arrest at 457 hospitals participating in the National Registry of Cardiopulmonary Resuscitation between January 1, 2000 and December 31, 2007. Neurological status was determined on admission and discharge by cerebral performance category with neurologically intact survival (NIS)=cerebral performance category 1 (no) or 2 (moderate dysfunction) and non-NIS=cerebral performance category 3 (severe dysfunction), 4 (coma), or 5 (brain death). Factors available prearrest (demographics, preexisting conditions, and interventions in-place) were assessed for association with NIS using multivariable logistic regression, initially without then with adjustment for arrest-related variables and hospital characteristics. NIS occurred in 2307 patients (17.7%) and was associated by adjusted odds ratio with 18 prearrest factors; 4 positively and 14 negatively. The association (odds ratio; 95% CI) was strongest for 4 specific variables: acute stroke (0.38; 0.25 to 0.58), history of malignancy (0.49; 0.39 to 0.63), vasopressor use (0.50; 0.43 to 0.59), and assisted or mechanical ventilation (0.53; 0.45 to 0.61).

Conclusions— A number of prearrest factors seem to be associated with NIS, the majority inversely. Consideration of these before cardiac arrest could enhance the resuscitative decision-making process for patients with acute heart failure.

Methods and Results— We studied 99 335 patients surviving first hospitalization for heart failure (HF) from 1997 to 2005. Use of HF medication and antidepressants (divided into tricyclic antidepressants [TCA] and SSRI) was determined by prescription claims. Risk of overall and cardiovascular death associated with antidepressants, HF medication, and coadministration of these 2 drug classes was estimated by Cox proportional hazard analyses. Propensity adjusted models were performed as sensitivity analysis. During the study period, there were 53 988 deaths, of which 83.0% were due to cardiovascular causes (median follow-up, 1.9 years; 5, 95% fractiles, 0.04 to 7.06 years). Use of β-blockers was associated with decreased risk of cardiovascular death (hazard ratio [HR], 0.77; 95% CI, 0.75 to 0.79). Antidepressants were prescribed to 19 411 patients, and both TCA and SSRI were associated with increased risk of overall and cardiovascular death (TCA: HR, 1.33; CI, 1.26 to 1.40; and HR, 1.25; CI, 1.17 to 1.32; SSRI: HR, 1.37; CI, 1.34 to 1.40; and HR, 1.34; CI, 1.30 to 1.38, respectively). Coadministration of SSRI and β-blockers was associated with a higher risk of overall and cardiovascular death compared with coadministration of β-blockers and TCA (P for interaction <0.01).

Conclusions— Use of antidepressants in patients with HF was associated with worse prognosis. Coadministration of SSRIs and β-blockers was associated with increased risk of overall death and cardiovascular death compared with coadministration of TCAs and β-blockers. To further clarify this, clinical trials testing the optimal antidepressant strategy in patients with HF are warranted.

Methods and Results— We analyzed echocardiographic data obtained within 6 months of listing for heart transplant and clinical data from 261 children with dilated cardiomyopathy who were included in both the Pediatric Cardiomyopathy Registry and the Pediatric Heart Transplant Study. Median time to listing after diagnosis was 1.9 months and to transplant after listing was 0.8 months. There were 42 deaths (29 waiting and 13 within 6 months after transplant). We found a significant age-dependent association of LV end-diastolic dimension z score (n=204, 31 deaths) with death controlling for race, transplant status, and medical insurance. The association was strongest for infants younger than 6 months at diagnosis (hazard ratio 1.47, P=0.008) and was not significant in children older than 5 years at diagnosis. A similar interaction was identified between age and LV end-systolic dimension z score (P=0.04). Neither LV function nor mass was associated with death, overall, or in subgroups.

Conclusions— The severity of LV dilation at listing for heart transplant is associated with outcome in infants and young children with dilated cardiomyopathy, whereas the severity of LV systolic dysfunction is not. These findings should be considered in risk stratification of these children at listing.

Methods and Results— Ten-day-old rabbits (n=6 per time point, total n=48) that underwent pulmonary artery banding were euthanized at 2 to 8 weeks after pulmonary artery banding, and comparisons were made with age-matched sham controls. LV performance (myocardial performance index) decreased during the progression of RVH, although the LV ejection fraction was maintained. In addition, RVH caused significant septal displacement, reduced septal contractility, and decreased LV end-systolic and end-diastolic dimensions, resulting in LV diastolic dysfunction with the appearance of preserved ejection fraction. Significant septal and LV free-wall apoptosis (myocyte-specific TUNEL and activated caspase-3), fibrosis (Masson trichrome stain), and reduced capillary density (CD31 immunostaining) occurred in the pulmonary artery banding group after 6 to 8 weeks (all P<0.05).

Conclusion— This is the first study showing that pressure overload of the right ventricular resulting in RVH causes LV diastolic dysfunction while preserving ejection fraction through mechanical and molecular effects on the septum and LV myocardium. In particular, the development of RVH is associated with septal and LV apoptosis and reduced LV capillary density.

Methods and Results— We measured the plasma levels of biomarkers such as BNP, ALD, adrenocorticotropic hormone, serum cortisol, and oxidized low-density lipoprotein (oxLDL), a biomarker of oxidative stress, in 319 consecutive symptomatic patients with chronic heart failure, and we followed these patients for a mean period of 33 months. During the follow-up period, 29 patients had cardiac events (death or hospitalization). Plasma levels of BNP, ALD, adrenocorticotropic hormone, oxLDL, and serum cortisol (16.8±1.8 µg/dL versus 12.4±0.3 µg/dL, P=0.01) were significantly higher in patients with cardiac events than in those without cardiac events. On stepwise multivariate analyses, high levels of BNP (P=0.0003), renin (P=0.002), cortisol (P=0.02), and oxLDL (P=0.002) were independent predictors of cardiac events, but ALD and adrenocorticotropic hormone levels were not. In patients with serum cortisol ≥12.5 µg/dL, the hazard ratio of cardiac events in patients with oxLDL ≥12 U/mL was 3.5 compared with that in patients with oxLDL <12 U/mL (P=0.008).

Conclusions— These findings indicate that serum cortisol levels were a complementary and incremental cardiac event risk predictor in combination with BNP in patients with chronic heart failure and that cardiac event prediction based on cortisol levels was influenced by oxidative stress.

Methods and Results— In 7448 patients with heart failure (75.2±11.5 years; 49.9% men) discharged from the hospital in Ontario, Canada, we examined the association of systolic blood pressure (SBP) and diastolic blood pressure with long-term survival. Parametric survival analysis was performed, and survival time ratios were determined according to discharge blood pressure group. A total of 25 427 person-years of follow-up were examined. In those with left ventricular ejection fraction ≤40%, median survival was decreased by 17% (survival time ratio, 0.83; 95% CI, 0.71 to 0.98; P=0.029) when discharge SBP was 100 to 119 mm Hg and decreased by 23% (survival time ratio, 0.77; 95% CI, 0.62 to 0.97; P=0.024) when discharge SBP was <100 mm Hg, compared with those in the reference range of 120 to 139 mm Hg. Survival time ratios were 0.75 (95% CI, 0.60 to 0.92; P=0.007) and 0.75 (95% CI, 0.53 to 1.07; P=0.12) when discharge SBPs were 140 to 159 and ≥160 mm Hg, respectively. In those with left ventricular ejection fraction >40%, survival time ratios were 0.69 (95% CI, 0.51 to 0.93), 0.83 (95% CI, 0.71 to 0.99), 0.95 (95% CI, 0.80 to 1.14), and 0.76 (95% CI, 0.61 to 0.95) for discharge SBPs <100, 100 to 119, 140 to 159, and ≥160 mm Hg, respectively.

Conclusions— In this long-term population-based study of patients with heart failure, the association of discharge SBP with mortality followed a U-shaped distribution. Survival was shortened in those with reduced or increased values of discharge SBP.

Methods and Results— Our main findings were (1) patients with chronic HF (n=188) had increased plasma levels of CXCL16, which correlated with disease severity. (2) Left ventricular tissue from patients with end-stage HF (n=8) showed enhanced CXCL16 levels compared with nonfailing left ventricular (n=6) as assessed by Western blotting. (3) In mice with postmyocardial infarction HF, expression of CXCL16, as assessed by real-time RT-PCR, was increased in the infarcted and the noninfarcted areas of left ventricular 3 and 7 days after coronary ligation, indicating early onset of CXCL16 production. Furthermore, mice exposed to aortic banding had enhanced CXCL16 expression in left ventricular, indicating that CXCL16 expression is not related to ischemia alone. (4) In vitro, CXCL16 promoted proliferation and impaired collagen synthesis in myocardial fibroblasts, and in cardiomyocytes and myocardial fibroblasts, CXCL16 increased matrix metalloproteinase activity, primarily reflecting increased matrix metalloproteinase-2 levels. (5) By using specific inhibitors, we showed that the effect of CXCL16 on fibroblasts involved activation of Jun N-terminal kinase.

Conclusion— We show enhanced myocardial CXCL16 expression in experimental and clinical HF. The effect of CXCL16 on cardiomyocytes and fibroblasts suggests a role for CXCL16 in matrix remodeling and ultimately in the development of HF.

Methods and Results— To determine the contribution of SMAD-dependent signaling to cardiac remodeling, we performed transaortic constriction in SMAD3 null (SMAD3^–/–) and littermate control mice (age, 10 to 12 weeks). Cumulative survival 20 days after transaortic constriction was significantly less in the SMAD3^–/– mice when compared with littermate controls (43.6% versus 90.9%, P<0.01). Transaortic constriction resulted in a significant increase in cardiac hypertrophy in the SMAD3^–/– mice, denoted by an increase in the heart weight to tibial length ratio and increased myocyte cross-sectional area. Loss of SMAD3 signaling also resulted in a significant 60% decrease in myocardial fibrosis (P<0.05). A microRNA microarray showed that 55 microRNAs were differentially expressed in littermate and SMAD3^–/– mice and that 10 of these microRNAs were predicted to bind to genes that regulate the extracellular matrix. Of these 10 candidate microRNAs, both miR-25 and miR-29a were sufficient to decrease collagen gene expression when transfected into isolated cardiac fibroblasts in vitro.

Conclusions— The results suggest that SMAD3 signaling plays dual roles in the heart: one beneficial role by delimiting hypertrophic growth and the other deleterious by modulating myocardial fibrosis, possibly through a pathway that entails accumulation of microRNAs that decrease collagen gene expression.

Methods and Results— EPDCs and cardiomyocyte progenitor cells were isolated from human adult atrial appendages, expanded in culture, and transplanted separately or together into the infarcted mouse myocardium (total cell number, 4x10⁵). Cardiac function was determined 6 weeks later (9.4T MRI). Coculturing increased proliferation rate and production of several growth factors, indicating a mutual effect. Cotransplantation resulted in further improvement of cardiac function compared with single cell-type recipients (P<0.05), which themselves demonstrated better function than vehicle-injected controls (P<0.05). However, in contrast to our hypothesis, no graft-derived cardiomyocytes were observed within the 6-week survival, supporting that not only EPDCs but also cardiomyocyte progenitor cells acted in a paracrine manner. Because injected cell number and degree of engraftment were similar between groups, the additional functional improvement in the cotransplantation group cannot be explained by an increased amount of secreted factors but rather by an altered type of secretion.

Conclusion— EPDCs and cardiomyocyte progenitor cells synergistically improve cardiac function after myocardial infarction, probably instigated by complementary paracrine actions. Our results demonstrate for the first time that synergistically acting cells hold great promise for future clinical regeneration therapy.

Methods and Results— Hearts from transplant recipients and unused donors were failing (n=12; mean ejection fraction, 24%) or nonfailing (n=9; mean ejection fraction, 59%) and similar in age (44 years) and sex (70% male). We measured the 1-AR subtypes in multiple regions of both ventricles by quantitative real-time reverse-transcription polymerase chain reaction and radioligand binding. All 3 1-AR subtype mRNAs were present, and 1A mRNA was most abundant (65% of total 1-AR mRNA). However, only 1A and 1B binding were present, and the 1B was most abundant (60% of total). In failing hearts, 1A and 1B binding was not downregulated, in contrast with β1-ARs.

Conclusions— Our data show for the first time that the 1A and 1B subtypes are both present in human myocardium, but 1D binding is not, and the 1 subtypes are not downregulated in heart failure. Because 1 subtypes in the human heart are similar to those in the mouse, where adaptive and protective effects of 1 subtypes are most convincing, it might become feasible to treat heart failure with a drug targeting the 1A and/or 1B.

Methods and Results— Under baseline conditions, isolated cardiac myocytes from TG mice showed an increased incidence of early afterdepolarizations compared with wild-type myocytes (P<0.05). CaMKII inhibition (AIP) completely abolished these afterdepolarizations in TG cells (P<0.05). Increasing intracellular Ca stores using ISO (10^–8 M) induced a larger amount of delayed afterdepolarizations and spontaneous action potentials in TG compared with wild-type cells (P<0.05). This seems to be due to an increased sarcoplasmic reticulum (SR) Ca leak because diastolic [Ca]_i rose clearly on ISO in TG but not in wild-type cells (+20±5% versus +3±4% at 10^–6 M ISO, P<0.05). In parallel, SR Ca leak assessed by spontaneous SR Ca release events showed an increased Ca spark frequency (3.9±0.5 versus 2.0±0.4 sparks per 100 µm^–1·s^–1, P<0.05). However, CaMKII inhibition (either pharmacologically using KN-93 or genetically using an isoform-specific CaMKII-knockout mouse model) significantly reduced SR Ca spark frequency, although this rather increased SR Ca content. In parallel, ISO increased the incidence of early (54% versus 4%, P<0.05) and late (86% versus 43%, P<0.05) nonstimulated events in TG versus wild-type myocytes, but CaMKII inhibition (KN-93 and KO) reduced these proarrhythmogenic events (P<0.05). In addition, CaMKII inhibition in TG mice (KN-93) clearly reduced ISO-induced arrhythmias in vivo (P<0.05).

Conclusions— We conclude that CaMKII contributes to cardiac arrhythmogenesis in TG CaMKII_C mice having heart failure and suggest the increased SR Ca leak as an important mechanism. Moreover, CaMKII inhibition reduces cardiac arrhythmias in vitro and in vivo and may therefore indicate a potential role for future antiarrhythmic therapies warranting further studies.

Methods and Results— All studies were performed using human cardiac tissue obtained from (1) hearts not matched for transplantation (nonfailing), (2) at the time of cardiac transplant (failing), or (3) paired samples at the time of VAD implant (pre-VAD) and removal (post-VAD). The expression of brain naturetic peptide, leptin, leptin receptor, and tumor necrosis factor mRNA was measured, and the protein expression of leptin and its receptor was examined by Western blot and immunofluorescent staining of cardiac sections. The assessment of leptin signaling was performed by measuring the phosphorylation state of the leptin receptor. The phosphorylation state of signal transducer and activator of transcription-3 and AMP-activated kinase proteins were also measured. All data are expressed as mean±SEM with a statistical significance in failing relative to nonfailing groups determined by Student independent t test, and the significance between pre- and post-VAD groups determined by paired t test. In failing human hearts, the mRNA expressions of leptin and its receptor were increased 5.4±0.3-fold (P<0.05) and 4.5±0.3-fold (P<0.05), respectively, with similar changes in protein. The phosphorylation state of both the leptin receptor and signal transducer and activator of transcription-3 proteins were increased 1.4±0.1-fold (P<0.05), and the level of phosphorylated AMP-activated kinase protein was increased 1.9±0.2-fold (P<0.05). Mechanical unloading of the failing human heart with a VAD resulted in no change in tumor necrosis factor expression but a marked decrease in leptin production to 1.7±0.1% (P<0.05) and leptin receptor expression to 3.0±0.2% (P<0.05) of pre-VAD levels. Phosphorylation of the leptin receptor, signal transducer and activator of transcription-3, and AMP-activated kinase were also decreased to 45±7%, 75±8%, and 58±8% of pre-VAD values, respectively (P<0.05 for all values).

Conclusions— These results indicate that the failing human heart increases expression of leptin and its receptor and that mechanical unloading downregulates this increase. Further, a cardioprotective role for leptin in the failing human heart is suggested through the activation of signal transducer and activator of transcription-3 and AMP-activated kinase signaling.

Methods and Results— IL-33 protected cultured cardiomyocytes from hypoxia-induced apoptosis, and this cardioprotection was partially inhibited by sST2. IL-33 induced expression of the antiapoptotic factors XIAP, cIAP1, and survivin. To define the cardioprotective role of IL-33 in vivo, we performed a blinded and randomized study of ischemia/reperfusion in rats. IL-33 reduced cardiomyocyte apoptosis, suppressed caspase-3 activity, and increased expression of IAP family member proteins. IL-33 decreased both infarct and fibrosis volumes at 15 days; furthermore, both echocardiographic and hemodynamic studies revealed that IL-33 improved ventricular function. To determine whether cardioprotection by IL-33 is mediated through ST2 signaling, a randomized and blinded study of ST2^–/– versus wild-type littermate mice was performed in 98 mice subjected to MI. At 4 weeks after MI, IL-33 reduced ventricular dilation and improved contractile function in wild-type mice but not in ST2^–/– mice. Finally, IL-33 improved survival after MI in wild-type but not in ST2^–/– mice.

Conclusion— IL-33 prevents cardiomyocyte apoptosis and improves cardiac function and survival after MI through ST2 signaling.

Methods and Results— Fifteen dogs were randomized into control (n=7) and VNS (n=8) groups. All dogs underwent 8 weeks of high-rate ventricular pacing (at 220 bpm for the first 4 weeks to develop HF and another 4 weeks at 180 bpm to maintain HF). Concomitant VNS, at an intensity reducing sinus rate 20 bpm, was delivered together with the ventricular pacing in the VNS group. At 4 and 8 weeks of ventricular pacing, both left ventricular end-diastolic and -systolic volumes were lower and left ventricular ejection fraction was higher in the VNS group than in the control group. Heart rate variability and baroreflex sensitivity improved in the VNS dogs. Rises in plasma norepinephrine, angiotensin II, and C-reactive protein levels, ordinarily expected in this model, were markedly attenuated with VNS treatment.

Conclusions— Chronic VNS improves cardiac autonomic control and significantly attenuates HF development in the canine high-rate ventricular pacing model. The therapeutic benefit of VNS is associated with pronounced anti-inflammatory effects. VNS is a novel and potentially useful therapy for treating HF.

Methods and Results— This study examined the hypothesis that HF promotes a loss of myosin protein from single skeletal muscle fibers, which in turn reduces contractile performance. Ten patients with chronic HF and 10 controls were studied. Muscle atrophy was not evident in patients, and groups displayed similar physical activity levels, suggesting that observed differences reflect the effects of HF and not muscle atrophy or disuse. In single muscle fibers, patients with HF showed reduced myosin heavy chain protein content (P<0.05) that manifested as a reduction in functional myosin-actin cross-bridges (P<0.05). No evidence was found for a generalized loss of myofilament protein, suggesting a selective loss of myosin. Accordingly, single muscle fiber maximal Ca²⁺-activated tension was reduced in myosin heavy chain I fibers in patients (P<0.05). However, tension was maintained in myosin heavy chain IIA fibers in patients because a greater proportion of available myosin heads were bound to actin during Ca²⁺ activation (P<0.01).

Conclusions— Collectively, our results show that HF alters the quantity and functionality of the myosin molecule in skeletal muscle, leading to reduced tension in myosin heavy chain I fibers. Loss of single fiber myosin protein content represents a potential molecular mechanism underlying muscle weakness and exercise limitation in patients with HF.