From the Guidelines
An echocardiogram is strongly recommended for this 70-year-old patient with a pro-BNP of 254 pg/mL, fatigue, and a TSH of 0.1 on levothyroxine 50 mcg, recently decreased from 75 mcg, to evaluate cardiac structure and function. The patient's symptoms of fatigue, combined with an elevated pro-BNP level, suggest the possibility of heart failure, which is further supported by the fact that advanced age is a non-cardiac cause of elevated natriuretic peptides, as outlined in Table 12.3 of the 2016 ESC guidelines for the diagnosis and treatment of acute and chronic heart failure 1. Although the pro-BNP level is only mildly elevated, the patient's hyperthyroidism is a concern, as thyroid dysfunction can impact cardiac function and potentially cause or exacerbate heart failure, as noted in the guidelines, which recommend assessing thyroid-stimulating hormone (TSH) in newly diagnosed heart failure patients 1.
The patient's recent decrease in levothyroxine dosage from 75 mcg to 50 mcg may also be relevant, as changes in thyroid hormone levels can affect cardiac function. An echocardiogram would provide valuable information about cardiac structure and function, including ejection fraction, wall motion abnormalities, valve function, and potential diastolic dysfunction, helping to determine if the patient's symptoms are cardiac-related and guiding appropriate management of both the cardiac and thyroid conditions. Key considerations in interpreting the pro-BNP level include the fact that normal levels make the diagnosis of heart failure unlikely, but elevated levels do not automatically confirm the diagnosis, as they can be associated with a wide variety of cardiac and non-cardiac causes, as outlined in the guidelines 1.
Given the complexity of this patient's presentation, with both cardiac and thyroid factors potentially contributing to their symptoms, a comprehensive evaluation, including an echocardiogram, is essential to guide management and improve outcomes. The guidelines emphasize the importance of assessing cardiac troponin, blood urea nitrogen (BUN), creatinine, electrolytes, liver function tests, and TSH in patients with suspected heart failure, highlighting the need for a thorough diagnostic approach 1.
From the Research
Patient Profile
- Age: 70 years
- Complaints: Fatigue
- TSH level: 0.1 on levothyroxine (recently decreased from 75 to 50)
- Pro BNP level: 254
Relevance of Pro BNP Level
- A pro BNP level of 254 is elevated, suggesting possible heart failure 2, 3, 4
- Elevated pro BNP levels are associated with increased mortality risk and poor outcomes in patients with heart failure 2
Correlation with Echocardiographic Parameters
- Pro BNP levels are significantly correlated with left ventricular end-systolic and end-diastolic diameter, left atrial diameter, and the degree of mitral insufficiency 3
- Pro BNP levels are also inversely correlated with left ventricular ejection fraction (LVEF) 3, 4
- A significant association exists between pro BNP levels and right ventricular basal and midsystolic velocities, as well as transmitral Epeak/Apeak ratio 3, 4
Diagnostic Utility of Echo and BNP Assessment
- The combination of echocardiography and BNP assessment can improve the diagnosis and management of heart failure 5, 6
- Echo-BNP guided management has been shown to reduce worsening renal function and improve outcomes in patients with chronic heart failure 5
- BNP levels can be used to estimate left ventricular filling pressure and diagnose congestive heart failure, with a cutoff value of >250 pg/ml having 86% sensitivity and 77% specificity 6
Consideration for Echo
- Given the patient's elevated pro BNP level and symptoms of fatigue, an echo may be considered to further evaluate left ventricular function and diagnose possible heart failure 2, 3, 4, 5, 6
- The combination of echocardiography and BNP assessment can provide valuable information for guiding management and improving outcomes in patients with heart failure 5, 6