Atrial natriuretic peptide as a predictor of atrial fibrillation in a male population study. The Study of Men Born in 1913 and 1923

The impact of volume substitution on post-operative atrial fibrillation

BACKGROUND

Post-operative atrial fibrillation (POAF) represents a common complication after cardiac valve or coronary artery bypass surgery. While strain of atrial tissue is known to induce atrial fibrillating impulses, less attention has been paid to potentially strain-promoting values during the peri- and post-operative period. This study aimed to determine the association of peri- and post-operative volume substitution with markers of cardiac strain and subsequently the impact on POAF development and promotion.

RESULTS

A total of 123 (45.4%) individuals were found to develop POAF. Fluid balance within the first 24 hours after surgery was significantly higher in patients developing POAF as compared to non-POAF individuals (+1129.6 mL [POAF] vs +544.9 mL [non-POAF], P = .044). Post-operative fluid balance showed a direct and significant correlation with post-operative N-terminal pro-brain natriuretic peptide (NT-ProBNP) values (r = .287; P = .002). Of note, the amount of substituted volume significantly proved to be a strong and independent predictor for POAF with an adjusted odds ratio per one litre of 1.44 (95% CI: 1.09-1.31; P = .009). In addition, we observed that low pre-operative haemoglobin levels at admission were associated with a higher need of intraoperative transfusions and volume-demand.

CONCLUSION

Substitution of larger transfusion volumes presents a strong and independent predictor for the development of POAF. Via the observed distinct association with NT-proBNP values, it can reasonably be assumed that post-operative atrial fibrillating impulses are triggered via increased global cardiac strain. Optimized pre-operative management of pre-existing anaemia should be considered prior surgical intervention in terms of a personalized patient care.

Decreased plasma musclin levels are associated with potential atrial fibrillation in non-diabetic patients

Background

Musclin is involved in the regulation of natriuretic peptide (NP) clearance and may affect the concentration of atrial natriuretic peptide (ANP). It has also been found to play an important role in several diseases, such as diabetes mellitus and hypertension. Both abnormalities in ANP and associated medical history are involved in the pathogenesis of atrial fibrillation (AF). However, plasma concentration of musclin as a biomarker for risk stratification in patients with AF has not been fully investigated.

Methods

Plasma musclin levels were measured in 290 patients with AF (including 199 paroxysmal AF patients and 91 persistent AF patients) and 120 control subjects. The association between plasma musclin levels and AF onset, as well as its predictive effects on clinical outcomes after cryoballoon ablation were analyzed.

Results

AF patients were found to have a lower concentration of plasma musclin than healthy controls. Moreover, in the non-diabetic group and normal N-terminal pro-brain natriuretic peptide (NT-proBNP) level group, the association between lower plasma concentration of musclin and AF remained significant. According to receiver operating characteristic (ROC) curve analysis, the optimal cut-off point of musclin for predicting AF onset was 54.94 ng/mL, which had a sensitivity of 81.67% and a specificity of 31.47% [area under the ROC curve (AUC) =60.71%]. In follow-up studies, both diabetes and left atrial size were independent predictors of AF recurrence after ablation, while musclin showed only a modest relationship with the outcome of cryoballoon ablation.

Conclusions

Our data indicated that decreased musclin was associated with the onset of AF. Moreover, lower plasma levels of musclin were an independent risk factor of AF in non-diabetic patients. Our studies suggest that musclin could be a predictive factor for the onset of AF.

NT -pro BNP as a Mediator of the Racial Difference in Incident Atrial Fibrillation and Heart Failure

Background

Blacks harbor more cardiovascular risk factors than whites, but experience less atrial fibrillation (AF). Conversely, whites may have a lower risk of heart failure (CHF). N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) levels are higher in whites, predict incident AF, and have diuretic effects in the setting of increased ventricular diastolic pressures, potentially providing a unifying explanation for these racial differences.

Methods and Results

We used data from the CHS (Cardiovascular Health Study) to determine the degree to which baseline NT‐proBNP levels mediate the relationships between race and incident AF and CHF by comparing beta estimates between models with and without NT‐proBNP. The ARIC (Atherosclerosis Risk in Communities) study was used to assess reproducibility. Among 4731 CHS (770 black) and 12 418 ARIC (3091 black) participants, there were 1277 and 1253 incident AF events, respectively. Whites had higher baseline NT‐proBNP (CHS: 40% higher than blacks; 95% CI, 29–53; ARIC: 39% higher; 95% CI, 33–46) and had a greater risk of incident AF compared with blacks (CHS: adjusted hazard ratio, 1.60; 95% CI, 1.31–1.93; ARIC: hazard ratio, 1.93; 95% CI, 1.57–2.27). NT‐proBNP levels explained a significant proportion of the racial difference in AF risk (CHS: 36.2%; 95% CI, 23.2–69.2%; ARIC: 24.6%; 95% CI, 14.8–39.6%). Contrary to our hypothesis, given an increased risk of CHF among whites in CHS (adjusted hazard ratio, 1.20; 95% CI, 1.05–1.47) and the absence of a significant association between race and CHF in ARIC (adjusted hazard ratio, 1.07; 95% CI, 0.94–1.23), CHF‐related mediation analyses were not performed.

Conclusions

A substantial portion of the relationship between race and AF was statistically explained by baseline NT‐proBNP levels. No consistent relationship between race and CHF was observed.

See Editorial by Richards

Atrial natriuretic peptide in cardiovascular biology and disease (NPPA)

Atrial natriuretic peptide (ANP) is a cardiac hormone that regulates salt-water balance and blood pressure by promoting renal sodium and water excretion and stimulating vasodilation. ANP also has an anti-hypertrophic function in the heart, which is independent of its systemic blood pressure-lowering effect. In mice, ANP deficiency causes salt-sensitive hypertension and cardiac hypertrophy. Recent studies have shown that ANP plays an important role in regulating vascular remodeling and energy metabolism. Variants in the human NPPA gene, encoding the ANP precursor, are associated with hypertension, stroke, coronary artery disease, heart failure (HF) and obesity. ANP and related peptides are used as biomarkers for heart disease. Recombinant proteins and small molecules that enhance the ANP pathway have been developed to treat patients with HF. In this review, we discuss the role of ANP in cardiovascular biology and disease.