Plasma atrial/A-type natriuretic peptide (ANP) concentration in horses with various heart diseases.

The research article investigates the potential diagnostic value of plasma atrial/A-type natriuretic peptide concentration (CpANP) in horses with various heart diseases. The study involved analyzing CpANP levels in both healthy animals and those with varying degrees of heart abnormalities.

Study Design and Methodology

• The study involved a total of 75 horses which were divided into four groups. Group 1 was made up of 15 healthy horses; Group 2 consisted of 24 horses with heart diseases but normal heart chamber size and function. Group 3 included 19 horses with abnormal left atrial size and/or function but a normal left ventricle; Lastly, Group 4 comprised 17 horses with both abnormal left atrial and left ventricle size and/or function.
• CpANP levels in the horses were measured with a commercially obtainable radioimmunoassay – a scientific method used to measure minute concentrations of substances within a solution.
• The echocardiographic measurements (ultrasound of the heart) of the horses were compared using statistical tests – one-way analysis of variance (ANOVA) and Holm-Sidak post-hoc test.
• Receiver Operating Characteristic (ROC) analyses were conducted to identify the most accurate cut-off points to distinguish between the groups.
• The relationship between the echocardiographic measurements and CpANP concentrations were evaluated using a backward stepwise multiple linear regression statistical method.

Results of the Study

• The study found that CpANP levels increase across the study groups – from healthy horses (Group 1) to those with the most severe heart abnormalities (Group 4). CpANP levels were significantly higher in horses that had heart diseases.
• Interestingly, CpANP was associated with the extent of left atrial area and changes in the left ventricular fractional area. These two are echocardiographic measurements which represent the specific sections and function of the left-sided heart chambers.
• However, when using ROC analyses, results showed good specificity (ability to correctly identify those without the disease) but poor sensitivity (ability to correctly identify those with the disease). This was specifically noted when differentiating between healthy horses and those with heart diseases, and also between healthy horses and those with altered left-sided chamber dimensions and/or function.

Conclusion of the Study

• While the study found that horses with heart diseases associated with altered left-sided heart chamber dimensions and/or function had increased CpANP levels, the diagnostic value of this biomarker is limited.
• Despite CpANP dictating an increase in horses suffering from heart disease, its diagnostic utility is compromised due to poor sensitivity, meaning it might often fail to identify horses with the disease correctly.