Study subjects and protocol
We enrolled 202 consecutive cancer patients, planned for cardiotoxic chemotherapy, including anthracyclines, human epidermal growth factor receptor 2 (HER2) inhibitors, tyrosine kinase inhibitors, and proteasome inhibitors at Fukushima Medical University hospital from November 2016 to March 2019 (Figure 1). Patients were excluded if they were died or transferred to other hospitals within 12 months follow-up period (n=33). Remaining 169 patients were divided into 2 groups based on the cut-off value of D-dimer, which was defined by receiver operator characteristic curve analysis to detect the occurrence of CTRCD (Figure 2).
Hypertension was defined as a history of use of antihypertensive drug or systolic blood pressure of ≥140 mmHg, and/or diastolic blood pressure ≥90 mmHg. Diabetes was defined as a recent use of insulin treatment or hypoglycemic drug, or hemoglobin A1c ≥6.5%. Dyslipidemia was defined as a history of use of cholesterol-lowering drugs, or triglyceride was ≥150 mg/dl, low density lipoprotein cholesterol was ≥140 mg / dl, and/or high-density lipoprotein cholesterol was ≤40 mg/dl. Cumulative dose of anthracycline was expressed as a doxorubicin equivalent [1]. HER2 inhibitor included trastuzumab and pertuzumab. Tyrosine kinase inhibitors included dabrafenib, trametinib, lenvatinib, sorafenib, dasatinib, bevacizumab, and pazopanib. Proteasome inhibitors included carfilzomib and bortezomib. Radiation therapy was defined as a irradiation to the mediastinum and/or the heart field within follow-up period. Transthoracic echocardiography and blood sampling test were performed at baseline, as well as at 3 months, 6 months, and 12 months after administration of cardiotoxic chemotherapy. All procedures used in this research were approved by the Ethical Committee of Fukushima Medical University.
Echocardiography
Transthoracic echocardiography was performed by a trained sonographer, and images were checked by another trained sonographer and an echo-cardiologist. We measured cardiac function using EPIQ 7G (Philips Healthtech, Best, Netherland). Left ventricular ejection fraction (EF) was calculated using the modified Simpson’s method according to the guideline from the American Society of Echocardiography and the European Association of Cardiovascular Imaging [9]. The left ventricular (LV) mass was calculated using the following formula
CTRCD was defined as a decrease in EF more than 10% points, to a value less than 53% [10]. LV end-diastolic volume index, LV end-systolic volume index, LV mass index, and left atrial volume index were measured using B-mode ultrasound.
Blood sampling
High sensitivity cardiac troponin I (TnI) was measured using an assay based on Luminescent Oxygen Channeling Immunoassay technology, and run on a Dimension EXL integrated chemistry system (Siemens Healthcare Diagnostics, Deerfield, IL, USA). B-type natriuretic peptide (BNP) levels were measured using a specific immunoradiometric assay (Shionoria BNP kit, Shionogi, Osaka, Japan). D-dimer was measured using a latex agglutination method (Lias Auto D-dimer Neo, Sysmex, Kobe, Japan).
Statistical analysis
All statistical analyzes were performed using Prism 9 (GraphPad Software, San diego, USA) or R software packages version 3.6.3 (R core team 2020, Vienna, Austria). We used the Shapiro-Wilk test to discriminate which variables were normally or not normally distributed. Normally distributed variables were shown as mean ± standard deviation. Non-normally distributed variables were indicated by median with interquartile range. Category variables were shown in numbers and percentage. Student’s t-test was used for variables following a normal distribution, the Mann-Whitney U-test was used for variables of the non-normal distribution, and the χ-square test was used for categorical variables. The time course of EF (baseline, 3-month, 6-month, and 12-month after the administration of anthracyclines) was evaluated using the Friedman test.
Logistic regression analysis was performed to identify the variables to predict the occurrence of CTRCD. We selected variables relating to general condition and cardiac function, including age, echocardiographic parameters, use of anthracyclines, BNP, hemoglobin, estimated glomerular filtration ratio, and the elevation of D-dimer. The variables presenting P value less than 0.05 in the univariable analysis were entered into the multivariable analysis. Receiver operating characteristic curve analysis was performed to determine the optimal cut-off value of D-dimer for predicting the occurrence of CTRCD. The P value of 0.05 or less was defined as significant.