Controversies in heart failure. Are beneficial effects of angiotensin-converting enzyme inhibitors attenuated by aspirin in patients with heart failure?

Diuretic Resistance in Heart Failure

Decompensated heart failure accounts for approximately 1 million hospitalizations in the United States annually, and this number is expected to increase significantly in the near future. Diuretics provide the initial management in most patients with fluid overload. However, the development of diuretic resistance remains a significant challenge in the treatment of heart failure. Due to the lack of a standard definition, the prevalence of this phenomenon remains difficult to determine, with some estimates suggesting that 25-30% of patients with heart failure have diuretic resistance. Certain characteristics, including low systolic blood pressures, renal impairment, and atherosclerotic disease, help predict the development of diuretic resistance. The underlying pathophysiology is likely multifactorial, with pharmacokinetic alterations, hormonal dysregulation, and the cardiorenal syndrome having significant roles. The therapeutic approach to this common problem typically involves increases in the diuretic dose and/or frequency, sequential nephron blockade, and mechanical fluid movement removal with ultrafiltration or peritoneal dialysis. Paracentesis is potentially useful in patients with intra-abdominal hypertension.

A perspective on diuretic resistance in chronic congestive heart failure

Chronic congestive heart failure (CHF) is a complex disorder characterized by inability of the heart to keep up the demands on it, followed by the progressive pump failure and fluid accumulation. Although the loop diuretics are widely used in heart failure (HF) patients, both pharmacodynamic and pharmacokinetic alterations are thought to be responsible for diuretic resistance in these patients. Strategies to overcome diuretic resistance include sodium intake restriction, changes in diuretic dose and route of administration and sequential nephron diuretic therapy. In this review, we discuss the definition, prevalence, mechanism of development and management strategies of diuretic resistance in HF patients.

Does aspirin use adversely influence intermediate-term postdischarge outcomes for hospitalized patients who are treated with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers? Findings from Organized Program to Facilitate Life-Saving Treatment in Hospitalized Patients with Heart Failure (OPTIMIZE-HF)

BACKGROUND

Conflicting data exist regarding a potential deleterious association between aspirin (ASA) and angiotensin-converting enzyme inhibitors (ACEIs) when used concurrently in patients with heart failure (HF). How such an interaction may be influenced by underlying etiology of HF and whether it extends to patients treated with angiotensin receptor blockers (ARBs), however, are not known.

METHODS

Eligible patients from the OPTIMIZE-HF registry were dichotomized into those with ischemic or nonischemic HF. Potential associations between ASA and ACEI or ARB use and 60- to 90-day postdischarge outcomes were assessed using Cox proportional and logistic regression modeling. Models were adjusted for factors known to influence the outcome of interest and by propensity score for ACEI or ARB prescription after an index HF admission.

RESULTS

Mortality was not increased (hazard ratio [95% CI]) when ASA was used in conjunction with ACEI (0.51 [0.29-0.87]) or ARB (0.29 [0.09-0.96]) in patients with ischemic or nonischemic (ACEI 0.71 [0.42-1.21], ARB 1.42 [0.74-2.74]) HF. Regression model parameter estimates trended toward harm reduction, but interaction terms for mortality and a composite of mortality or rehospitalization were nonsignificant (P for all >.05).

CONCLUSIONS

When combined with ACEI or ARB, ASA had no demonstrable adverse effect on intermediate-term postdischarge outcomes for patients with ischemic or nonischemic HF.

Cyclooxygenase inhibition causes marked impairment of renal function in elderly subjects treated with diuretics and ACE-inhibitors

BACKGROUND

Treatment with angiotensin-converting enzyme (ACE)-inhibitors is known to cause an initial reduction in glomerular filtration rate (GFR) in patients with congestive heart failure. The long-term beneficial effects of ACE-inhibitors in these patients can be counteracted by cyclooxygenase-inhibitors.

AIMS

To quantify the negative renal effects of the cyclooxygenase-inhibitor diclofenac in elderly healthy subjects and to assess how treatment with an ACE-inhibitor, after activation of the renin-angiotensin system, influences these renal effects.

METHODS

Fourteen elderly, healthy subjects received oral diclofenac and placebo in a double-blind cross-over fashion. The study was divided in two parts; in part one, subjects received no pre-treatment and in part two, the subjects were given pre-treatment with bendroflumethiazide and enalapril in order to activate the renin-angiotensin system.

RESULTS

Diclofenac induced significant (p<0.05) decreases in GFR, urine flow, excretion rates of sodium and potassium, electrolyte clearance, osmolality clearance and free water clearance both with and without renin-angiotensin system activation. Least square means (95% CI) of all observations during the first 6 h after dosing showed that diclofenac caused a reduction in GFR from 71 (64-78) to 59 (52-66) ml/min. After pre-treatment, diclofenac further reduced GFR from 60 (52-67) to 48 (40-55) ml/min. After diclofenac administration, urine flow fell from 7.4 (6.4-8.3) to 5.1 (4.2-6.1) ml/min, after pre-treatment, diclofenac gave a further reduction from 4.1 (3.1-5.1) to 2.2 (1.3-3.2) ml/min. More than half of the reductions were caused by the pre-treatment.

CONCLUSION

Renal function in elderly, healthy subjects is impaired after acute intake of diclofenac. This impairment is observed both with and without activation of the renin-angiotensin system and ACE-inhibitor treatment but is more pronounced after pre-treatment.

Aspirin Use in Older Patients With Heart Failure and Coronary Artery Disease

OBJECTIVES

We sought to determine patterns of aspirin use and the relationship between aspirin prescription and outcomes in patients with coronary artery disease (CAD) and heart failure (HF).

BACKGROUND

Because of the potential for exacerbating hypertension or renal insufficiency and possible interactions with angiotensin-converting enzyme (ACE) inhibitors, the use of aspirin for secondary prevention of coronary events is controversial in patients with HF.

METHODS

We studied a national sample of Medicare beneficiaries > or =65 years old after hospitalization for HF with CAD and without aspirin contraindications between April 1998 and June 2001. We assessed factors associated with aspirin prescription and the relationship between aspirin and outcomes in regression models accounting for differences in patient, physician, and hospital characteristics and for clustering of patients by hospital.

RESULTS

Of the 24,012 patients, 54% received aspirin. Treated patients had lower unadjusted rates of death (31% vs. 39% for those not receiving aspirin, p < 0.001). In multivariable analyses, aspirin remained associated with a lower risk of death (risk ratio [RR] 0.94; 95% confidence interval [CI] 0.90 to 0.99). This association was similar regardless of hypertension, renal insufficiency, or treatment with ACE inhibitors (p for all interactions > 0.2). Aspirin also was associated with lower risks of death or all-cause readmission (RR 0.98; 95% CI 0.97 to 0.99) and of death or readmission for HF (RR 0.98; 95% CI 0.96 to 0.99).

CONCLUSIONS

Almost one-half of patients with CAD hospitalized for HF in the U.S. are not treated with aspirin. This study found no evidence of harm from aspirin in this population and suggests a treatment benefit. Withholding aspirin based upon theoretical concerns about adverse effects appears to be unjustified.

Effect of Combined Treatment with Aspirin and Dipyridamole on Oxidative Homeostasis in Mouse Serum

Using the method of peroxidative luminol-dependent chemiluminescence we showed that combined treatment with aspirin in low dose and dipyridamole corrects imbalance in oxidative homeostasis in mouse serum. This state resulted from a sharp increase in prooxidant processes after platelet disaggregation with normal dose of aspirin or dose-dependent inhibition of free radical processes with dipyridamole.

Prolonged aspirin inhibition of anodal vasodilation is not due to the trafficking delay of neural mediators

We previously reported that forearm vasodilation to a delivered all-at-once over 5 min or a 1-min repeated monopolar anodal 0.10-mA current application is aspirin sensitive and that a single high-dose aspirin exerts a long-lived effect in the former case. We hypothesized that 1) in the latter case, the effect of aspirin would also be long lived and 2) the time required to resupply nerve endings with unblocked cyclooxygenase through axonal transport could explain this phenomenon. We studied the time course for the recovery of vasodilation to repeated current application after placebo or 1-g aspirin treatment. We then searched for a difference at a proximal vs. distal site in the recovery of the response. Aspirin abolished current-induced vasodilation at 2 h, 10 h, and 3 days, with a progressive recovery thereafter, but no difference between distal and proximal site was observed for the recovery of the response. This suggests that, although neural cyclooxygenase could participate in the response, the time course of aspirin inhibition of current-induced cutaneous vasodilation is not due to the time required through neural transport to resupply nerve endings with unblocked proteins.

Heart failure as a cause for hospitalization in chronic dialysis patients

BACKGROUND

Risk factors for heart failure (HF) have not been reported previously in a nationally representative sample of dialysis patients.

METHODS

We conducted a historic cohort study of 1,995 patients enrolled in the US Renal Data System Dialysis Morbidity and Mortality Study Wave 2 who were Medicare eligible at the study start and were followed up until December 31, 1999, or receipt of a renal transplant. Cox regression analysis was used to model associations with time to first hospitalization for both recurrent and de novo HF (International Classification of Diseases, Ninth Revision code 428.x), defined as patients with and without a history of HF, respectively.

RESULTS

The incidence density of HF was 71/1,000 person-years. Angiotensin-converting enzyme inhibitors and beta-blockers were each used in less than 25% of patients with a known history of HF. A history of coronary heart disease was associated with an increased total risk for HF, as were hemodialysis (versus peritoneal dialysis), aspirin use, and a history of diabetes. However, hemodialysis and aspirin use were the only factors associated with both de novo and recurrent HF. Widened pulse pressure was associated with de novo HF. The mortality rate after HF was 83% at 3 years (adjusted hazard ratio for mortality, 2.10; 95% confidence interval, 1.80 to 2.45; P < 0.0001).

CONCLUSION

In chronic dialysis patients, hemodialysis and aspirin use were associated with increased risk for both total and de novo HF. Hospitalized HF was associated with a significantly increased risk for death.

Comparative effects of aspirin with ACE inhibitor or angiotensin receptor blocker on myocardial infarction and vascular function

OBJECTIVES

We previously showed that an angiotensin-converting enzyme inhibitor (captopril) or an angiotensin receptor blocker (losartan) reduced infarct size and improved endothelial function in a rat model of ischaemia-reperfusion. The present study was undertaken to see if aspirin (ASA) antagonised the beneficial effects of captopril or losartan.

METHODS

One hundred and fourteen Sprague-Dawley rats were randomised into six groups; Control, ASA, captopril, losartan, ASA+captopril, and ASA+losartan. ASA, captopril or losartan were given at a concentration of 40 mg/kg/day in drinking water. After six weeks of pre-treatment, the rats were subjected to 17 minutes of left anterior descending coronary artery occlusion and 120 minutes of reperfusion, with haemodynamic and ECG monitoring. During the reperfusion period, the effective refractory period (ERP), ventricular fibrillation threshold (VFT) and bleeding time (BT) were measured. In fresh aortic rings precontracted with phenylephrine, endothelium-dependent and -independent relaxations were assessed using acetylcholine and nitroglycerin.

RESULTS

Haemodynamic changes were not different between the groups. Serum ASA concentrations were 0.5, 1.1 and 0.6 mg/dl in the ASA, ASA+captopril and ASA+losartan groups, respectively, and BT was prolonged (p<0.01). ASA alone reduced endothelium-dependent relaxation (-29+8 vs. -69+11%, p<0.01), but did not change endothelium-independent relaxation. ASA did not affect endothelial relaxation induced by acetylcholine in the presence of either captopril or losartan. Angiotensin I and ERP were elevated by captopril and losartan. Angiotensin II and VFT were elevated by losartan. ASA with captopril, captopril and losartan equally reduced infarct size, compared with control (39+3, 39+4, and 39+5 vs. 53+3%, all p<0.05).

CONCLUSIONS

Captopril and losartan had similar cardiovascular protective effects in a rat model of ischaemia-reperfusion. Aspirin did not attenuate the cardiovascular protective effects of captopril or losartan.

Analysis of a large cohort of health maintenance organization patients with congestive heart failure

The aim of this article was to measure guideline compliance in the care of health plan members diagnosed with congestive heart failure (CHF). Chart review was conducted on members with a discharge diagnosis of CHF (n = 2,697). Information was entered onto a scannable form designed by the health plan, which was coupled to an optical character recognition reader and entered into a database. Eighty-four percent of the patients had an ejection fraction (EF) measured. An angiotensin-converting enzyme inhibitor was prescribed to 72% of patients with an EF less than 40%. Comorbidities and other measures were evaluated and based on guideline recommendations. Most of the CHF patients in this health plan are being treated appropriately during posthospitalization for CHF. The use of a novel, cost-effective method for data collection resulted in the rapid acquisition of clinical data for analysis.

Heart failure and the brain: new perspectives

Despite recent therapeutic advances, the prognosis for patients with heart failure remains dismal. Unchecked neurohumoral excitation is a critical element in the progressive clinical deterioration associated with the heart failure syndrome, and its peripheral manifestations have become the principal targets for intervention. The link between peripheral systems activated in heart failure and the central nervous system as a source of neurohumoral drive has therefore come under close scrutiny. In this context, the forebrain and particularly the paraventricular nucleus of the hypothalamus have emerged as sites that sense humoral signals generated peripherally in response to the stresses of heart failure and contribute to the altered volume regulation and augmented sympathetic drive that characterize the heart failure syndrome. This brief review summarizes recent studies from our laboratory supporting the concept that the forebrain plays a critical role in the pathogenesis of ischemia-induced heart failure and suggesting that the forebrain contribution must be considered in designing therapeutic strategies. Forebrain signaling by neuroactive products of the renin-angiotensin system and the immune system are emphasized.

Pharmacotherapy in congestive heart failure: diuretic resistance and strategies to overcome resistance in patients with congestive heart failure

Congestive heart failure is a complex clinical hemodynamic disorder characterized by chronic and progressive pump failure and fluid accumulation. Although the overall impact of diuretic therapy on congestive heart failure mortality remains unknown, diuretics remain a vital component of symptomatic congestive heart failure management. Over time, sodium and water excretion are equalized before adequate fluid elimination occurs. This phenomenon is thought to occur in one out of three patients with congestive heart failure on diuretic therapy and is termed diuretic resistance. In congestive heart failure, both pharmacokinetic and pharmacodynamic alterations are thought to be responsible for diuretic resistance. Due to disease chronicity, symptomatic management is vital to improved quality of life and enhancing diuretic response is therefore pivotal.