Reversal of peripheral microvascular dysfunction during long-term treatment with the angiotensin-converting enzyme inhibitor fosinopril in congestive heart failure

Thenar Muscle Oxygen Saturation Using Vascular Occlusion Test: A Novel Technique to Study Microcirculatory Abnormalities in Pediatric Heart Failure Patients

Heart failure (HF) is associated with microcirculatory changes secondary to neuro-humoral imbalance, vascular stiffness and increased sympathetic tone. Near Infra-Red Spectroscopy (NIRS) derived Thenar muscle tissue oxygenation levels (StO₂) can provide an estimate of the functional status of microcirculation. There is a paucity of literature regarding evaluation of microcirculation in pediatric subjects with HF. We hypothesized that microcirculation and oxygen saturation dynamics as assessed by Thenar StO₂ levels using vascular occlusion test (VOT) would be altered in HF subjects and that these changes may correlate with the severity of heart failure. We prospectively enrolled 60 pediatric subjects (29 healthy control, 31 HF). Baseline StO₂ levels were measured using InSpectra™ StO₂ probe placed over the Thenar eminence of right hand, followed by a VOT for 3 min, during which the changes in StO₂ levels during the occlusion phase and post occlusion phase were recorded. Baseline Thenar StO₂ levels (72 ± 8 vs 76 ± 5, p = 0.02) and time to baseline StO₂ in seconds (150 ± 70 vs 200 ± 70, p = 0.007) were significantly lower in HF group compared to healthy control (HC). In addition, HF patients had a significantly lower trough StO₂ (37 ± 9 vs 42 ± 11%, p =  0.04) and peak StO₂ compared to HC (87 ± 8 vs 91 ± 5%, p = 0.01). However, there was no difference in the rate of desaturation, rate of resaturation or time to peak StO₂ levels in between the 2 groups. Significant correlation was present between baseline Thenar StO₂ levels and NYU Pediatric Heart Failure Index Score (NYU-PHFI) (p = 0.003). This study is the first to report an objective assessment of microcirculation and Thenar tissue oxygen dynamics in pediatric subjects with HF in comparison with HC. Our study suggests altered microcirculation and oxygenation patterns in these subjects as well as correlation with a validated pediatric heart failure clinical score. Large-scale prospective studies are needed to further study the utility of this novel technology in HF subjects.

Peripheral artery disease: potential role of ACE-inhibitor therapy

Subjects with peripheral arterial disease (PAD) of the lower limbs are at high risk for cardiovascular and cerebrovascular events and the prevalence of coronary artery disease in such patients is elevated. Recent studies have shown that regular use of cardiovascular medications, such as therapeutic and preventive agents for PAD patients, seems to be promising in reducing long-term mortality and morbidity. The angiotensin-converting-enzyme (ACE) system plays an important role in the pathogenesis and progression of atherosclerosis, and ACE-inhibitors (ACE-I) seem to have vasculoprotective and antiproliferative effects as well as a direct anti-atherogenic effect. ACE-I also promote the degradation of bradykinin and the release of nitric oxide, a potent vasodilator; further, thay have shown important implications for vascular oxidative stress. Other studies have suggested that ACE-I may also improve endothelial dysfunction. ACE-I are useful for reducing the risk of cardiovascular events in clinical and subclinical PAD. Particularly, one agent of the class (ie, ramipril) has shown in many studies to able to significantly reduce cardiovascular morbidity and mortality in patients with PAD.

[Head-to-head comparison of clinical, biochemical and functional effects of fosinopril and enalapril in patients with systolic heart failure]

INTRODUCTION

The aim of this study was to evaluate short-term clinical, biochemical and functional effects of fosinopril versus enalapril in patients with heart failure.

MATERIAL AND METHODS

59 consecutive patients (mean age 57 +/- 8 years, EF 18.9 +/- 6.3%, NYHA III or IV class 19/59) were randomized to receive fosinopril or enalapril for three months. All patients underwent echocardiography, metabolic testing, and a 6-minute walk test and completed the Minnesota questionnaire on inclusion and three months later. Additionally, serum creatinine, BUN, total cholesterol and triglycerides were measured. Kaplan-Meier curve was created to assess event-free survival for cardiac death and hospitalization for heart failure.

RESULTS

There was no statistically significant difference in event-free survival between patients on fosinopril and enalapril (86.7% vs. 82.8%, log rank 4.21 p=0.43). However, time to the event was longer in patients on fosinopril (77.0 +/- 25.35 vs. 40.2 +/- 6.8 days, p=0.04). At the end of the study, no difference between fosinopril and enalapril group existed with respect to maximal oxygen consumption (20.90 +/- 4.47 vs. 20.89 +/- 6.86 ml/kg/min), ejection fraction (20.5 +/- 7.4 vs. 21.4 +/- 7.8%), distance during the 6-minute test walk (313 +/- 74 vs. 352 +/- 129 meters) and quality of life (23.8 +/- 15.8 vs. 25.6 +/- 20.3 points), but patients on enalapril had higher creatinine (99 +/- 13 vs. 113 +/- 17 micromol/L, p=0.002) and BUN (7.28 +/- 1.7 vs. 8.89 +/- 2.39 mmol/L, p=0.01) levels. Increase in fosinopril dose during the study was higher than increase in enalapril dose (24.1% +/- 23.8% vs. 9.5 +/- 24.5%, p=0.04).

CONCLUSIONS

Fosinopril and enalapril have similar short-term effects on event-free survival, ejection fraction, functional capacity and quality of life in patients with heart failure. Patients on fosinopril presented with longer survival without event and had lower creatinine and BUN at the end-of the follow-up. Additionally, fosinopril can be easily titrated to the maximum therapeutic dose.