Is the lower mortality in patients treated with aspirin and angiotensin-converting enzyme inhibitors due to decreased norepinephrine release?

Sympathetic nervous system overactivity and its role in the development of cardiovascular disease

This review examines how the sympathetic nervous system plays a major role in the regulation of cardiovascular function over multiple time scales. This is achieved through differential regulation of sympathetic outflow to a variety of organs. This differential control is a product of the topographical organization of the central nervous system and a myriad of afferent inputs. Together this organization produces sympathetic responses tailored to match stimuli. The long-term control of sympathetic nerve activity (SNA) is an area of considerable interest and involves a variety of mediators acting in a quite distinct fashion. These mediators include arterial baroreflexes, angiotensin II, blood volume and osmolarity, and a host of humoral factors. A key feature of many cardiovascular diseases is increased SNA. However, rather than there being a generalized increase in SNA, it is organ specific, in particular to the heart and kidneys. These increases in regional SNA are associated with increased mortality. Understanding the regulation of organ-specific SNA is likely to offer new targets for drug therapy. There is a need for the research community to develop better animal models and technologies that reflect the disease progression seen in humans. A particular focus is required on models in which SNA is chronically elevated.

Does aspirin attenuate the effect of angiotensin-converting enzyme inhibitors on health outcomes of very old patients with heart failure?

OBJECTIVES

Concomitant ischemic heart disease (IHD) is common in older individuals with heart failure (HF). We estimated the effect of aspirin use on the rate of mortality, morbidity, and decline in physical functioning in nursing home residents with HF taking angiotensin-converting enzyme (ACE) inhibitors.

DESIGN

We conducted a retrospective cohort study using a nursing home database linking resident information collected via the Minimum Data Set (MDS) with drug utilization data.

SETTING

Nursing homes in four states (1992-1995).

PARTICIPANTS

Of 49,779 residents with HF admitted to these homes, 12,703 residents were taking an ACE inhibitor; 2,046 of these took aspirin.

MEASUREMENTS

Medicare enrollment files provided the date of death, and we used the Part A Medicare files to identify hospital admissions. The activity of daily living scale from repeat MDS assessments allowed us to evaluate decline in physical function. Cox proportional hazards models provided adjusted estimates of the aspirin effect, with nonusers as the reference group.

RESULTS

The overall mortality rate, hospitalization rate,and rate of decline in physical function of aspirin users were not different from those of nonusers (e.g., hospitalization rate ratio = 0.99, 95% confidence interval = 0.92-1.07). This effect did not vary by presence of concomitant IHD or by dose or type of ACE inhibitor.

CONCLUSION

In a cohort of older HF residents receiving ACE inhibitors in nursing homes, we found that treatment with aspirin did not appear to affect outcomes negatively.