Novel Mitochondria-Targeting Peptide in Heart Failure Treatment: A Randomized, Placebo-Controlled Trial of Elamipretide.

BACKGROUND: Mitochondrial dysfunction and energy depletion in the failing heart are innovative therapeutic targets in heart failure management. Elamipretide is a novel tetrapeptide that increases mitochondrial energy; however, its safety, tolerability, and therapeutic effect on cardiac structure and function have not been studied in heart failure with reduced ejection fraction. METHODS AND RESULTS: In this double-blind, placebo-controlled, ascending-dose trial, patients with heart failure with reduced ejection fraction (ejection fraction, ≤35%) were randomized to either a single 4-hour infusion of elamipretide (cohort 1 [n=8], 0.005; cohort 2 [n=8], 0.05; and cohort 3 [n=8], 0.25 mg·kg-1·h-1) or placebo control (n=12). Safety and efficacy were assessed by clinical, laboratory, and echocardiographic assessments performed at pre-, mid- and end-infusion and 6-, 8-, 12- and 24-hours postinfusion start. Peak plasma concentrations of elamipretide occurred at end-infusion and were undetectable by 24 hours postinfusion. There were no serious adverse events. Blood pressure and heart rate remained stable in all cohorts. Compared with placebo, a significant decrease in left ventricular end-diastolic volume (-18 mL; P=0.009) and end-systolic volume (-14 mL; P=0.005) occurred at end infusion in the highest dose cohort. CONCLUSIONS: This is the first study to evaluate elamipretide in heart failure with reduced ejection fraction and demonstrates that a single infusion of elamipretide is safe and well tolerated. High-dose elamipretide resulted in favorable changes in left ventricular volumes that correlated with peak plasma concentrations, supporting a temporal association and dose-effect relationship. Further study of elamipretide is needed to determine long-term safety and efficacy. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02388464.

Phase 2 study of TAK-442, an oral factor Xa inhibitor, in patients following acute coronary syndrome.

TAK-442 is an oral direct factor Xa inhibitor. We sought to determine the dose-dependent effect of TAK-442 on major bleeding when added to standard treatment in stabilised patients with acute coronary syndrome (ACS). In this phase II double-blind study, 2,753 ACS patients were randomised to TAK-442 or placebo in addition to usual care using a three-stage adaptive design. Patients were randomised to placebo in all stages, but doses of TAK-442 escalated from 10 mg BID, 20 mg twice-daily (BID), or 40 mg once-daily (QD) in stage 1; to 40 mg BID, 80 mg QD, or 80 mg BID in stage 2; and to 160 mg QD or 120 mg BID in stage 3. Study drug was started 36 hours after emergent treatment of ACS and within seven days of admission, and continued for 24 weeks. The primary endpoint was incidence of TIMI (thrombolysis in myocardial infarction) major bleeding. TIMI major bleeding incidence was low, but higher with the pooled TAK-442 doses than with placebo (17 [0.9%] vs 4 [0.5%]; p=0.47), although the difference was neither significant nor dose-dependent. However, a dose response was evident when using the modified ISTH scale. The incidence of cardiovascular events was similar among TAK-442 dose groups and placebo. When administered over a wide range of doses after an ACS event, TAK-442 treatment did not result in a dose-dependent increase in TIMI major bleeding, but increased bleeding was observed when a more sensitive bleeding scale was used. There was no evidence for efficacy.

Is thrombosis a contributor to heart failure pathophysiology? Possible mechanisms, therapeutic opportunities, and clinical investigation challenges.

Thrombotic events (coronary thrombosis, venous thromboembolism, intraventricular thrombosis, intracranial and systemic thromboembolism) occur frequently in patients with heart failure. These events may be precipitated by several mechanisms including hypercoagulability through enhancement of procoagulant reactions, impairment of the protein C pathway, protease activated receptor (PAR) activation, adenosine-mediated thrombosis, or neurohormonal activation; stasis secondary to low cardiac output; and endothelial dysfunction from neurohormonal activation or systemic inflammation. Pathophysiologic evidence and analyses of retrospective data support the hypothesis that antithrombotic agents may improve outcomes in patients with heart failure. Warfarin has not been shown to reduce clinical events in patients with heart failure, although several of the completed randomized trials were underpowered, and the most recent was not placebo-controlled. Many unanswered questions remain that justify continued research in this area. This paper examines the conceptual framework, opportunities, and challenges of clinical investigative approaches with the newer anti-thrombotic agents in patients with heart failure. Critical questions are raised with regard to clinical trial designs that warrant consideration as the field progresses.

Implications of geographical variation on clinical outcomes of cardiovascular trials.

Cardiovascular clinical trials are increasingly conducted globally as a means to reduce costs, expedite timelines, provide broad applicability, and satisfy regulatory authorities. Potential problems with trial globalization include regional differences in patient characteristics, medical practice patterns, and health policies which may influence outcomes and limit generalizability. Moreover, concerns have been raised about ethical misconduct and unsatisfactory quality oversight in regions with less trial experience and infrastructure. This article reviews geographical differences in cardiovascular trials in heart failure, acute coronary syndromes, hypertension and atrial fibrillation. It also explores potential explanations for these differences and methods to standardize the presentation of trial results. This review is based on discussions between basic scientists and clinical trialists at the 8th Global Cardio Vascular Clinical Trialists Forum 2011 in Paris, France, from December 2 to 3.

Subgroup analysis of a randomized controlled trial evaluating the safety and efficacy of cardiac contractility modulation in advanced heart failure.

BACKGROUND: Cardiac contractility modulation (CCM) signals are nonexcitatory electrical signals delivered during the absolute refractory period intended to improve contraction. We previously tested the safety and efficacy of CCM in 428 NYHA functional class III/IV heart failure patients with EF ≤35% and narrow QRS randomized to optimal medical treatment (OMT) plus CCM (n = 215) versus OMT alone (n = 213) and found no significant effect on ventilatory anaerobic threshold (VAT), the study's primary end point. In the present analysis, we sought to identify if there was a subgroup of patients who showed a response to CCM. METHODS AND RESULTS: The protocol specified that multiregression analysis would be used to determine if baseline EF, NYHA functional class, pVO(2), or etiology of heart failure influenced the impact of CCM on AT. Etiology and baseline pVO(2) did not affect efficacy. However, baseline NYHA functional class III and EF ≥25% were significant predictors of increased efficacy. In this subgroup (comprising 97 OMT and 109 CCM patients, ∼48% of the entire population) VAT increased by 0.10 ± 2.36 in CCM versus -0.54 ± 1.83 mL kg(-1) min(-1) in OMT (P = .03) and pVO(2) increased by 0.34 ± 3.11 in CCM versus -0.97 ± 2.31 (P = .001) at 24 weeks compared with baseline; 44% of CCM versus 23% of OMT subjects showed improvement of ≥1 class in NYHA functional class (P = .002), and 59% of CCM versus 42% of OMT subjects showed a ≥10-point reduction in Minnesota Living with Heart Failure Questionnaire (P = .01). All of these findings were similar to those seen at 50 weeks. CONCLUSIONS: The results of this retrospective hypothesis-generating analysis indicate that CCM significantly improves objective parameters of exercise tolerance in a subgroup of patients characterized by normal QRS duration, NYHA functional class III symptoms, and EF >25%.

A randomized controlled trial evaluating the safety and efficacy of cardiac contractility modulation in advanced heart failure.

BACKGROUND: Cardiac contractility modulation (CCM) delivers nonexcitatory electrical signals to the heart during the absolute refractory period intended to improve contraction. METHODS: We tested CCM in 428 New York Heart Association class III or IV, narrow QRS heart failure patients with ejection fraction (EF) ≤ 35% randomized to optimal medical therapy (OMT) plus CCM (n = 215) versus OMT alone (n = 213). Efficacy was assessed by ventilatory anaerobic threshold (VAT), primary end point, peak Vo2 (pVo2), and Minnesota Living with Heart Failure Questionnaire (MLWFQ) at 6 months. The primary safety end point was a test of noninferiority between groups at 12 months for the composite of all-cause mortality and hospitalizations (12.5% allowable delta). RESULTS: The groups were comparable for age (58 ± 13 vs 59 ± 12 years), EF (26% ± 7% vs 26% ± 7%), pVo2 (14.7 ± 2.9 vs 14.8 ± 3.2 mL kg⁻¹ min⁻¹), and other characteristics. While VAT did not improve at 6 months, CCM significantly improved pVo2 and MLWHFQ (by 0.65 mL kg⁻¹ min⁻¹ [P = .024] and -9.7 points [P < .0001], respectively) over OMT. Forty-eight percent of OMT and 52% of CCM patients experienced a safety end point, which satisfied the noniferiority criterion (P = .03). Post hoc, hypothesis-generating analysis identified a subgroup (characterized by baseline EF ≥ 25% and New York Heart Association class III symptoms) in which all parameters were improved by CCM. CONCLUSIONS: In the overall target population, CCM did not improve VAT (the primary end point) but did improve pVo2 and MLWHFQ. Cardiac contractility modulation did not have an adverse affect on hospitalizations or mortality within the prespecified boundaries. Further study is required to clarify the role of CCM as a treatment for medically refractory heart failure.

The influence of renal function on clinical outcome and response to beta-blockade in systolic heart failure: insights from Metoprolol CR/XL Randomized Intervention Trial in Chronic HF (MERIT-HF).

BACKGROUND: Limited information is available on the risk and impact of renal dysfunction on the response to beta-blockade and mode of death in systolic heart failure (HF). METHODS AND RESULTS: Renal function was estimated with glomerular filtration rate (eGFR) using the simplified Modification of Diet in Renal Disease (MDRD) equation. Patients from the Metoprolol CR/XL Controlled Randomized Intervention Trial in Chronic HF (MERIT-HF) were divided into 3 renal function subgroups (MDRD formula): eGFR(MDRD) > 60 (n = 2496), eGFR(MDRD) 45 to 60 (n = 976), and eGFR(MDRD) < 45 mL/min per 1.73 m(2) body surface area (n = 493). Hazard ratio (HR) was estimated with Cox proportional hazards models adjusted for prespecified risk factors. Placebo patients with eGFR < 45 had significantly higher risk than those with eGFR > 60: HR for all-cause mortality, 1.90 (95% confidence interval [CI], 1.28 to 2.81) comparing placebo patients with eGFR < 45 and eGFR > 60, and for the combined end point of all-cause mortality/hospitalization for worsening HF (time to first event): HR, 1.91 (95% CI, 1.44 to 2.53). No significant increase in risk with deceased renal function was observed for those randomized to metoprolol controlled release (CR)/extended release (XL) due to a highly significant decrease in risk on metoprolol CR/XL in those with eGFR < 45. For total mortality, metoprolol CR/XL vs placebo: HR, 0.41 (95% CI. 0.25 to 0.68; P < .001) in those with eGFR < 45 compared with HR, 0.71 (95% CI, 0.54 to 0.95; P < .021) for those with eGFR > 60; corresponding data for the combined end point was HR, 0.44 (95% CI, 0.31 to 0.63; P < .0001) and HR, 0.75 (0.62 to 0.92; P = .005, respectively; P = .095 for interaction by treatment for total mortality; P = .011 for combined end point). Metoprolol CR/XL was well tolerated in all 3 renal function subgroups. CONCLUSIONS: Renal function as estimated by eGFR was a powerful predictor of death and hospitalizations from worsening HF. Metoprolol CR/XL was at least as effective in reducing death and hospitalizations for worsening HF in patients with eGFR < 45 as in those with eGFR > 60.

Atenolol is inferior to metoprolol in improving left ventricular function and preventing ventricular remodeling in dogs with heart failure.

OBJECTIVES: beta-Blockers are standard therapy for patients with heart failure (HF). This study compared the effects of chronic monotherapy with 2 different beta(1)-selective adrenoceptor blockers, namely atenolol and metoprolol succinate, on left ventricular (LV) function and remodeling in dogs with coronary microembolization-induced HF [LV ejection fraction (EF) 30-40%]. METHODS: Twenty HF dogs were randomized to 3 months of therapy with atenolol (50 mg once daily, n = 6), metoprolol succinate (100 mg, once daily, n = 7) or to no therapy (control, n = 7). LV EF and volumes were measured before initiating therapy and after 3 months of therapy. The change (Delta) in EF and volumes between measurements before and after therapy was calculated and compared among study groups. RESULTS: In controls, EF decreased and end-systolic volume increased. Atenolol prevented the decrease in EF and the increase in ESV. In contrast, metoprolol succinate significantly increased EF and decreased end-systolic volume. DeltaEF was significantly higher and Deltaend-systolic volume significantly lower in metoprolol succinate-treated dogs compared to atenolol-treated dogs (EF: 6.0 +/- 0.86% vs. 0.8 +/- 0.85%, p < 0.05; end-systolic volume: -4.3 +/- 0.81 ml vs. -1 +/- 0.52 ml, p <0.05). CONCLUSIONS: In HF dogs, chronic therapy with atenolol does not elicit the same LV function and remodeling benefits as those achieved with metoprolol succinate.

Effect of long-term monotherapy with the aldosterone receptor blocker eplerenone on cytoskeletal proteins and matrix metalloproteinases in dogs with heart failure.

PURPOSE: Long-term monotherapy with the aldosterone receptor blocker eplerenone in dogs with HF was previously shown to improve LV systolic and diastolic function. This study examined the effects of long-term monotherapy with the aldosterone receptor blocker eplerenone on mRNA and protein expression of the cytoskeletal proteins titin, tubulin, fibronectin and vimentin, the matrix metalloproteinases (MMPs)-1, -2 and -9, and the tissue inhibitors of MMPs (TIMPs)-1 and -2 in left ventricular (LV) myocardium of dogs with heart failure (HF). METHODS: HF was produced in 12 dogs by intracoronary microembolizations. Dogs were randomized to 3 months oral therapy with eplerenone (10 mg/kg twice daily, n = 6) or to no therapy at all (HF-control, n = 6). LV tissue from six normal dogs was used for comparison. mRNA expression was measured using reverse-transcriptase polymerase chain reaction (RT-PCR) and protein expression using Western blots. RESULTS: Compared to NL dogs, control dogs showed upregulation of mRNA and protein expression for tubulin, fibronectin, MMP-1, -2 and -9, and down-regulation of mRNA and protein expression for total titin. Normalization of mRNA and protein expression for all these genes was seen after treatment with eplerenone. N2BA/N2B-titin mRNA expression ratio increased significantly in dogs with HF treated with eplerenone. No differences in expression for vimentin, TIMP-1 and -2 were observed among groups. CONCLUSIONS: In dogs with HF, long-term eplerenone therapy normalizes mRNA and protein expression of key cytoskeletal proteins and MMPs. Reversal of these molecular maladaptations may partly explain the improvement in LV diastolic function seen after long-term therapy with eplerenone.

Chronic monotherapy with rosuvastatin prevents progressive left ventricular dysfunction and remodeling in dogs with heart failure.

OBJECTIVES: This study examined the effects of long-term monotherapy with rosuvastatin (RSV) on the progression of left ventricular (LV) dysfunction and remodeling in dogs with heart failure (HF). BACKGROUND: 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors or "statins" possess other noncholesterol-lowering properties that include inhibiting proinflammatory cytokines, attenuating LV hypertrophy, and stimulating the release of bone marrow-derived stem cells (BMSCs). METHODS: Twenty-one dogs with microembolization-induced HF were randomized to 3 months oral monotherapy with low-dose (LD) RSV (0.5 mg/kg once daily, n = 7), high-dose (HD) RSV (3.0 mg/kg once daily, n = 7), or to no therapy (control group, n = 7). The change (Delta) from pre- to post-therapy (treatment effect) in LV end-diastolic volume (EDV) and end-systolic volume (ESV) and ejection fraction (EF) was measured. Protein level of tumor necrosis factor (TNF)-alpha in LV tissue and the number of circulating Sca-1-positive BMSCs was also determined. Blood and LV tissue from 6 normal dogs was obtained and used for comparison. RESULTS: There were no differences in DeltaEDV, DeltaESV, and DeltaEF between control group and LD RSV. In contrast, DeltaEDV and DeltaESV were significantly lower, and DeltaEF was significantly higher in HD RSV compared with control group. High-dose, but not LD, RSV also normalized protein levels of TNF-alpha and was associated with a significant increase in the number of circulating BMSCs. CONCLUSIONS: In dogs with HF, chronic therapy with HD RSV prevents progressive LV dysfunction and dilation. This benefit may be partly derived from normalization of TNF-alpha expression and partly from increased mobilization of BMSCs.

Globalization of cardiovascular clinical research: the balance between meeting medical needs and maintaining scientific standards.

A substantial need to conduct research studies and identify effective treatments for cardiovascular diseases in the developing world exists. Careful consideration of several issues is warranted to ensure that clinical trials conducted solely in developing nations are held to accepted scientific standards. Researchers conducting clinical trials in developing countries should critically evaluate the purpose and appropriateness of conducting the trial in the proposed location, the accessibility of the therapy if proven effective, the quality of the informed consent process, the presence of infrastructure to support clinical research, and the translation of data to other populations. This article discusses the importance of these considerations using a recent example of a clinical trial conducted in a developing nation. These and other issues are critical to address as the conduct of cardiovascular clinical trials continues to expand beyond the western world.

Left atrial reverse remodeling in dogs with moderate and advanced heart failure treated with a passive mechanical containment device: an echocardiographic study.

BACKGROUND: Assessment of global left ventricular (LV) remodeling is important in evaluating the efficacy of pharmacologic and device therapies for the treatment of chronic heart failure (HF). The effects of pharmacologic or device therapies on global left atrial (LA) remodeling in HF, although also important, are not often examined. We showed that long-term therapy with the Acorn Cardiac Support Device (CSD), a passive mechanical ventricular containment device, prevents or reverses LV remodeling in dogs with HF. This study examined the effects of the CSD on global LA remodeling in dogs with moderate and advanced HF. METHODS AND RESULTS: Studies were performed in 24 dogs with coronary microembolization-induced HF. Of these, 12 had moderate HF (ejection fraction, EF 30% to 40%) and 12 advanced HF (EF < or = 25%). In each group, the CSD was implanted in 6 dogs and the other 6 served as controls. Dogs were followed for 3 months in the moderate group and 6 months in the advanced HF group. LA maximal volume (LAVmax), LA volume at the onset of the p-wave (LAVp), LA minimal volume (LAVmin), LA active emptying volume (LAAEV), and LA active emptying fraction (LAAEF) were measured from 2-dimensional echocardiograms obtained before CSD implantation and at the end of the treatment period. Treatment effect (delta) comparisons between CSD-treated dogs and controls showed that CSD therapy significantly decreased LA volumes (deltaLAVmax: 3.33 +/- 0.70 vs. -2.87 +/- 1.31 mL, P = .002; 7.77 +/- 1.76 versus -0.37 +/- 0.87 mL, P = .002) and improved LA function (deltaLAAEF: -6.00 +/- 1.53 versus 1.85 +/- 1.32%, P = .003; -2.39 +/- 1.10 versus 3.13 +/- 1.66%, P = .02) in the moderate HF and advanced HF groups, respectively. CONCLUSIONS: Progressive LA enlargement and LA functional deterioration occurs in untreated dogs with HF. Monotherapy with the CSD prevents LA enlargement and improves LA mechanical function in dogs with moderate and advanced HF indicating prevention or reversal of adverse LA remodeling.

Associations of gender and etiology with outcomes in heart failure with systolic dysfunction: a pooled analysis of 5 randomized control trials.

OBJECTIVES: This study sought to explore the gender-related differences in etiology and outcomes in chronic heart failure (HF) patients from 5 randomized trials. BACKGROUND: Each year, 550,000 new cases of HF are identified; however, there remain limited data on gender-related differences in etiology and outcomes among patients with HF with systolic dysfunction. METHODS: We analyzed data from 8,791 men and 2,851 women randomized in 5 clinical trials (PRAISE [Prospective Randomized Amlodipine Survival Evaluation], PRAISE-2, MERIT-HF [Metoprolol Extended Release Randomized Intervention Trial in Heart Failure], VEST [Vesnarinone Trial], and PROMISE [Prospective Randomized Milrinone Survival Evaluation]) to explore gender-related differences in etiology (ischemic vs. nonischemic) and outcomes (all-cause mortality and death or all-cause hospitalization). Hazard ratios (HR), 95% confidence intervals (CIs), and Kaplan-Meier survival curves were generated by gender and etiology. RESULTS: A total of 18% of ischemic and 31% of nonischemic patients were women. Irrespective of etiology, women were older, more ethnically diverse, and had higher systolic blood pressures, more diabetes, and severe HF symptoms, but less often smoked or had prior myocardial infarctions than men. Mean ejection fractions were similar between women (23.6%) and men (23.2%). The 1-year Kaplan-Meier survival estimates varied by gender and etiology (female nonischemics, HR 0.88 [95% CI 0.85 to 0.89]; female ischemics, HR 0.83 [95% CI 0.81 to 0.85]; male nonischemics, HR 0.84 [95% CI 0.83 to 0.85]; male ischemics, HR 0.79 [95% CI 0.78 to 0.81]). After adjustment, female gender (HR 0.77 [95% CI 0.69 to 0.85]) and nonischemic etiology (HR 0.80 [95% CI 0.72 to 0.89]) were associated with longer survival time. Time to death or hospitalization was longer among nonischemics (HR 0.83 [95% CI 0.78 to 0.89], p < 0.0001); however, female gender was not significantly associated with the composite outcome (HR 1.01 [95% CI 0.95 to 1.08]). CONCLUSIONS: Our data clarify that outcomes differ by both gender and etiology among patients with HF with systolic dysfunction. Understanding these differences may lead to better management of HF patients and improved overall prognosis.

Long-term pharmacological activation of PPARgamma does not prevent left ventricular remodeling in dogs with advanced heart failure.

BACKGROUND: Peroxisome proliferator-activated receptor gamma (PPARgamma) activators affect the myocardium through inhibition of inflammatory cytokines and metabolic modulation but their effect in the progression of heart failure is unclear. In the present study, we examined the effects of the PPARgamma activator, GW347845 (GW), on the progression of heart failure. METHODS AND RESULTS: Heart failure was produced in 21 dogs by intracoronary microembolizations to LV ejection fraction (EF) less than 30% and randomized to 3 months of therapy with high-dose GW (10 mg/Kg daily, n = 7), low-dose GW (3 mg/Kg daily, n = 7), or no therapy (control, n = 7). In control dogs, EF significantly decreased (28 +/- 1 vs. 22 +/- 1%, p < 0.001) and end-diastolic volume (EDV) and end-systolic volume (ESV) increased during the 3 months of the follow-up period (64 +/- 4 vs. 76 +/- 5; p = 0.003, 46 +/- 3 vs. 59 +/- 4 ml, p = 0.002, respectively). In dogs treated with low-dose GW, EDV increased significantly (69 +/- 4 vs.81 +/- 5 ml, p = 0.01), whereas ESV remained statistically unchanged (50 +/- 3 vs. 54 +/- 3 ml, p = 0.10) resulting in modestly increased ejection fraction (27 +/- 1 vs. 32 +/- 3%, p = 0.05). In dogs treated with high-dose GW, both EDV and ESV increased (72 +/- 4 vs. 79 +/- 5 ml, p = 0.04; 53 +/- 3 vs. 62 +/- 5 ml, p = 0.04) and EF decreased (26 +/- 1 vs. 23 +/- 1%, p = 0.04) as with control dogs. There was significantly increased myocardial hypertrophy as evidenced by increased LV weight to body weight ratio and myocyte cross-section area in the GW treated animals compared to controls. Compared to control, treatment with GW had no effect on mRNA expression of PPARgamma, inflammatory cytokines, stretch response proteins, or transcription factors that may induce hypertrophy. CONCLUSIONS: Long-term PPARgamma activation with GW did not prevent progressive LV remodeling in dogs with advanced heart failure.

Hemodynamic and neurohormonal predictors and consequences of the development of atrial fibrillation in dogs with chronic heart failure.

BACKGROUND: Heart failure increases the risk of atrial fibrillation (AF), which frequently results in heart failure progression. This prospective study examined the contribution of hemodynamic and neurohormonal activation to the spontaneous occurrence of AF in heart failure, and assessed the effects of AF on left ventricular (LV) function and neurohormonal activation. METHODS AND RESULTS: Heart failure (LV ejection fraction [LVEF] 25%-30%) was induced in 27 dogs via sequential coronary microembolizations. Hemodynamic and neurohormonal measurements were performed at 1 month (prior to development of AF) and 4 months post-embolization. During the time between measurements, 10 dogs developed spontaneous AF. Plasma norepinephrine concentration (PNE) at 1 month was higher in animals that subsequently developed AF (576 + 101 vs. 425 + 197 pg/mL, P = .03). There were no significant differences between the groups in 1-month LV end-diastolic pressure (LVEDP), pulmonary artery wedge pressure (PAWP), cardiac output, end-diastolic volume (EDV), LVEF, or plasma renin activity (PRA). At 4 months, cardiac output was lower (2.1 + .4 vs. 2.6 + .6 L/h, P = .02) and PNE was higher (1036 + 857 vs. 508 + 288 pg/mL, P = .03) in dogs with AF versus those in sinus rhythm. There were no significant differences between groups in 4-month LVEDP, PAWP, EDV, LVEF, or PRA. CONCLUSION: Spontaneous AF in heart failure was preceded by a significant increase in PNE. In animals that developed AF, there was a further decline in cardiac output and increase in PNE.

Selective matrix metalloproteinase inhibition attenuates progression of left ventricular dysfunction and remodeling in dogs with chronic heart failure.

Matrix metalloproteinases (MMPs) contribute to the progression of left ventricular (LV) dysfunction and remodeling associated with heart failure (HF). The present study examined the long-term effects of a selective MMP inhibitor PG-530742 (PG) on the progression of LV dysfunction and remodeling in dogs with HF. Chronic HF [LV ejection fraction (LVEF),

Consistency of the beneficial effect of metoprolol succinate extended release across a wide range dose of angiotensin-converting enzyme inhibitors and digitalis.

BACKGROUND: The effects of beta-blockade with different extent of angiotensin-converting enzyme inhibitors (ACEI) and digitalization are unknown. To assess the effect of metoprolol succinate controlled release/extended release (CR/XL) combined with high versus low doses of ACEI and digitalis, we analyzed data from The Metoprolol CR/XL Randomized Intervention Trial in Chronic Heart Failure (MERIT-HF) in which patients with heart failure and left ventricular ejection fraction < or =40% were randomized to metoprolol CR/XL versus placebo. METHODS AND RESULTS: Outcome was analyzed separately for those on a low dose (< or =median) of the ACEI or digitalis versus high dose (> median). The mean dose of ACEI in the high-dose group (n = 1457) was 3 times higher than that in the low-dose group (n = 2094). Mortality was reduced to a similar extent in the high- and low-dose ACEI subgroups (RR = .69 versus .64, respectively). Corresponding figures for combined mortality/all hospitalization and for mortality/hospitalization for heart failure were .85 versus .83, and .70 versus .68, respectively. Likewise, reduction in total mortality with metoprolol CR/XL was similar in patients receiving no digitalis (n = 1447; RR = .56), low dose (n = 1122; RR = .71), or high dose (n = 1421; RR = .71). CONCLUSION: This analysis of MERIT-HF demonstrates consistent and similar improvement in outcome of patients receiving metoprolol CR/XL when combined with either a high or low dose of an ACEI or digitalis, or no digitalis at all. Thus regardless of ACEI and digitalis dose and whether patients are treated with digitalis or not, it is very important to add a beta-blocker to the existing heart failure therapy. beta-blockers should not be withheld until target doses of ACEI have been achieved.