Rapid changes of atrial natriuretic peptide concentration during percutaneous transluminal coronary angioplasty

Use of pro-atrial natriuretic peptide in the detection of myocardial ischaemia

BACKGROUND

Because of its unique storage and release mechanisms allowing a very rapid response to haemodynamic changes, pro-atrial natriuretic peptide (proANP) may be a helpful cardiac marker in the detection of myocardial ischaemia.

MATERIALS AND METHODS

A total of 260 consecutive patients with suspected myocardial ischaemia referred for rest/ergometry myocardial perfusion single-photon emission computed tomography (SPECT) were enrolled. Levels of plasma proANP were determined before and 1 min after maximal exercise.

RESULTS

Baseline proANP and peak exercise proANP were significantly higher in patients with myocardial ischaemia as compared to those without ischaemia (median, 82 [IQR, 57-112] vs. 67 [IQR, 50-106] pmol L(-1), P = 0.007; and 89 [IQR, 65-121] vs. 78 [IQR, 57-116] pmol L(-1), P = 0.033). The area under the ROC curve for baseline proANP was 0.597 (95% CI, 0.527-0.667), as compared to 0.577 (95% CI, 0.507-0.648) for peak exercise proANP. Exercise-induced changes in proANP were similar in patients with and without myocardial ischaemia, and showed no correlation with the extent of myocardial ischaemia.

CONCLUSIONS

Baseline proANP and peak exercise proANP are significantly higher in patients with myocardial ischaemia. However, because of considerable overlap in proANP levels between patients with and without myocardial ischaemia, neither measurement seems helpful in the detection of myocardial ischaemia in clinical practice.

Association of plasma atrial natriuretic peptide, N-terminal proatrial natriuretic peptide, and brain natriuretic peptide levels with coronary artery stenosis in patients with normal left ventricular systolic function

PURPOSE

To examine whether coronary artery stenosis affects plasma levels of atrial natriuretic peptide (ANP), N-terminal proatrial natriuretic peptide (proANP), and brain natriuretic peptide (BNP) in patients with normal left ventricular systolic function.

METHODS

We studied 104 consecutive patients with normal left ventricular function and suspected coronary artery stenosis. Plasma natriuretic peptide levels were measured by immunoradiometric assays.

RESULTS

Plasma levels of ANP, N-terminal proANP, and BNP were higher in patients with (n = 65) than in those without (n = 39) coronary artery stenosis, whereas hemodynamic variables were similar. Patients who had coronary artery stenosis with only distal lesions (n = 36) had higher levels of all three natriuretic peptides than did patients with no coronary artery stenosis. N-terminal proANP levels were significantly higher in patients who had coronary artery stenosis with proximal lesions (n = 29) than in patients who had coronary artery stenosis with only distal lesions and those with no coronary artery stenosis. Multiple logistic regression analysis revealed that N-terminal proANP, but not ANP or BNP, was independently associated with coronary artery stenosis after adjusting for clinical and demographic variables (odds ratio per 100 fmol/mL increase = 1.9; 95% confidence interval: 1.9 to 2.6; P = 0.01). However, the sensitivity, specificity, and positive and negative predictive values of each peptide were not sufficiently high to be used for prediction.

CONCLUSION

N-terminal proANP may be associated with clinically important coronary artery stenosis in patients with normal left ventricular systolic function, but its clinical usefulness may be limited.

Cardiac natriuretic peptides--hope or hype?

In recent years, biomedical science has witnessed the emergence of peptide biochemicals as significant topics of research. Some of these peptides are of little potential clinical use, while others, of which cardiac natriuretic peptides are an example, appear to be promising. This particular group of peptides (i.e. ANP, BNP and CNP) shows promising diagnostic as well as therapeutic potential for various pathological conditions. In the case of acute myocardial infarction, these peptides have significant diagnostic and predictive properties, more so than other biochemicals such as adrenaline, renin and aldosterone. In addition, ANP is found to have significant benefits over the classical anti-anginal drug glyceryl trinitrate. However, as is the case with other peptides, applying these benefits clinically may not be easy because of the structure of the compounds, but various strategies are now being applied to solve this problem. These include the use of non-peptide receptor ligands, inhibitors of ANP metabolism, gene therapy and so on. The development of drugs in clinical practice, which exploits the natriuretic peptides system therefore seems to be promising, and this article reviews advances in our understanding of these compounds.

Natriuretic peptides: physiology, therapeutic potential, and risk stratification in ischemic heart disease

BACKGROUND

The natriuretic peptide family consists of four molecules that share significant amino acid sequence homologic characteristics and a looped motif. Atrial natriuretic peptide and brain natriuretic peptide are similar in their ability to promote natriuresis and diuresis, inhibit the renin-angiotensin-aldosterone axis, and act as vasodilators. Understanding of the actions of C-type natriuretic peptide and dendroaspis natriuretic peptide is incomplete, but these two new family members also act as vasodilators. Because of the rapid evolution of information about this peptide family, we reviewed the state of the art with respect to risk stratification and therapeutic ability.

METHODS

English-language papers were identified by a MEDLINE database search covering 1966 through 1997 and supplemented with bibliographic references and texts.

CONCLUSIONS

The natriuretic peptides are counterregulatory hormones with prognostically important levels. They are similarly upregulated in heart failure and counteract neurohormones that induce vasoconstriction and fluid retention. BNP may be the superior prognosticator for risk stratification after myocardial infarction and is independent of left ventricular ejection fraction. Lastly, experimental trials suggest that administration of exogenous natriuretic peptides or inhibitors of their catabolism to patients with ischemic heart disease may be clinically beneficial.

Atrial natriuretic peptide and N-terminal atrial natriuretic peptide in plasma reflect right ventricular volumes following coronary artery surgery

BACKGROUND

Atrial natriuretic peptide (ANP) and the more stable N-terminal fragment (N-ANP) of prohormone are peptides, released in equimolar amounts from cardiac myocytes in response to atrial stretch or ventricular overload and myocardial ischaemia. Protection of the right ventricular (RV) myocardium during ischaemia in cardiac surgery is difficult, especially in patients with severe right coronary artery (RCA) disease. This prospective study was designed to ascertain a possible relationship between changes in plasma ANP/N-ANP concentration and RV function in RCA-diseased patients.

METHODS

Plasma ANP and N-ANP concentrations and RV function, measured by fast-response thermodilution, were determined serially in 15 patients with total RCA stenosis and in another 15 with no significant RCA disease (controls) before, during and after coronary surgery.

RESULTS

The RV ejection fraction was lower and the RV end-systolic volume index higher in the RCA-diseased patients than in the controls (P < 0.05) on the second postoperative day, and both ANP and N-ANP were higher in the RCA patients (P < 0.05) from 6 h after cardiopulmonary bypass till the second postoperative day. At the same time the changes in N-ANP concentrations from the levels before induction of anaesthesia correlated with RV ejection fraction and RV volume indexes, but not with heart rate or parameters indirectly reflecting left-sided loading. Right atrial pressure did not differ between the groups nor did it increase significantly during the study.

CONCLUSIONS

The relationships found between N-ANP and RV volume indexes and RV ejection fraction suggest ventricular expression of ANP: ANP release may be stimulated by RV distension, the more so the poorer the RV function.