Abstract 13612: Association Between B-Type Natriuretic Peptide and Inferior Vena Cava Diameter as a Measure of Hypovolemia in Cancer Patients

Abstract

Introduction: Hypovolemia is frequently seen in cancer patients due to catabolism, cachexia, and decreased oral intake. However, volume status assessment in this population is often difficult due to competing comorbid conditions such as edema. Elevated B-type natriuretic peptide (BNP) is an established biomarker of myocardial wall stress in patients with hypervolemia. We sought to determine if very low BNP could be an objective marker of hypovolemia in cancer patients Hypothesis: In cancer patients undergoing treatment, is low BNP level (<10 pg/mL) associated with small inferior vena cava (IVC) diameter (< 1.4 cm) - an established marker of hypovolemia on transthoracic echocardiography (TTE)?We hypothesize that BNP <10 pg/mL is associated with small IVC as a marker of hypovolemia in cancer patients. Methods: We conducted a retrospective study (N=91) with solid malignancies, undergoing chemo- and/or radiation therapy (RT), divided into 3 groups based on BNP values in pg/mL: low (BNP <10), normal (BNP 10-100) and high (BNP>100). Retrospective data were obtained between 2016-2023 from Rush University Medical Center Cardio-Oncology Registry. IVC measurements by 2 medial trainees (Cohen’s intraclass correlation coefficient = 0.87, p < 0.01) were acquired from formal TTEs obtained within 1 week of BNP measurements. Linear regression was used to calculate the adjusted means (for age, sex, BMI, blood pressure, creatinine, RT, TSH) of the 2 measured IVC diameters per datapoint. Mean difference in IVC diameters was compared between the 3 BNP groups. Results: The population mean age was 59.99 ± 12.19, 67% women. Adjusted mean IVC measurements were 1.89cm, 1.55cm, and 1.26cm for the high, normal, and low BNP groups respectively. The mean difference in IVC diameters between high and low BNP groups was 0.628 ±0.164 cm (p<0.01). Conclusions: In cancer patients undergoing treatment, very low BNP (<10pg/mL) was associated with small IVC as a marker of hypovolemia. In this group of patients, BNP measured with routine lab data is a readily available tool to identify individuals with hypovolemia where other measures of volume status such as physical exams might be uncertain.