Chimeric antigen receptor T- Cell (CAR-T) immunotherapy has been a breakthrough treatment for various hematological malignancies. However, cardiotoxicities such as new-onset heart failure, arrhythmia, acute coronary syndrome and cardiovascular death occur in 10–15% of patients treated with CAR-T. This study aims to investigate the changes in cardiac and inflammatory biomarkers in CAR-T therapy to determine the role of pro-inflammatory cytokines.In this observational study, ninety consecutive patients treated with CAR-T underwent baseline cardiac investigation with electrocardiogram (ECG), transthoracic echocardiogram (TTE), troponin-I, and B-type natriuretic peptide (BNP). Follow-up ECG, troponin-I and BNP were obtained five days post- CAR-T. In a subset of patients (N = 53), serum inflammatory cytokines interleukin (IL)-2, IL-6, IL-15, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, granulocyte-macrophage colony-stimulating factor (GM-CSF), and angiopoietin 1 & 2 were tested serially, including baseline and daily during hospitalization. Adverse cardiac events were defined as new-onset cardiomyopathy/heart failure, acute coronary syndrome, arrhythmia and cardiovascular death.2; p = 0.042). Day 5 BNP levels , but not troponin-I, were higher in patients with adverse cardiac events, compared to those without. The maximum levels of IL-6 , IFN-γ  and IL-15  were also higher in the adverse cardiac events group. However, cardiac and inflammatory biomarker levels were not associated with cardiac events. Patients who developed cardiac events did not exhibit worse survival compared to patients without cardiac events (Log-rank p = 0.200).Eleven patients (12%) had adverse cardiac events . Adverse cardiac events appear to have occurred among patients with advanced age , higher baseline creatinine  and higher left atrial volume index . The changes in serial inflammatory cytokine after CAR-T in the setting of adverse cardiac events suggests pro-inflammation as a pathophysiology and require further investigation for their role in adverse cardiac events.CAR-T related Cardiotoxicity has elevated cardiac and inflammatory biomarkers. #CARTCell #CardioOnc #CardioImmunology.The online version contains supplementary material available at 10.1186/s40959-023-00170-5. Chimeric antigen receptor T- Cell (CAR-T) immunotherapy has been a breakthrough for various CD19 + hematological malignancies, including lymphoma . One serThe pathophysiology of these cardiovascular toxicities is thought to be secondary to CRS and potentiated by both cardiac and non-cardiac risk factors , 10. TheThe purpose of this study was to investigate the changes of cardiac biomarkers and inflammatory cytokines that occur in the setting of adverse cardiac events after CAR-T therapy.This was an observational study in a single, National Cancer Institute (NCI)-designated academic center (H. Lee Moffitt Cancer Center). This study was approved by the IRB of the University of South Florida (Pro00029257 and Pro00021733). Participating patients provided informed consent for the quantification of inflammatory cytokines. Inclusion criteria included patients diagnosed with B-cell lymphoma  who were treated with four types of CAR-T therapy . As a collaborative work between our cardio-oncology team and CAR-T team, we set up standard clinical practice guidelines at our institution beginning October 2020. Consecutive patients undergoing CAR-T therapy from October 2020 until October 2021 underwent baseline and follow-up cardiac biomarkers. This study included a retrospective review clinical data, as summarized in below section. In addition, of the consecutive patients reviewed, there were subset of patients who were enrolled in prospective observational study investigating the validity of daily cytokine monitoring system for CRS.Baseline cardiac investigation at the time of evaluation for CAR-T therapy included electrocardiogram, transthoracic echocardiogram, troponin-I, and B-type natriuretic peptide (BNP). Follow-up ECG, troponin-I, and BNP levels were obtained five days after CAR-T infusion and at the development of CRS Grade ≥2 (fever with hypotension or hypoxia). The CRS grading was based on published guidelines by the American Society for Transplantation and Cellular Therapy (ASTCT) . The carSeparate to this study, a subset of patients were enrolled in a prospective study on inflammatory biomarkers in subjects who underwent CAR-T (USF IRB Pro00021733). The study was open to all patients who underwent commercial CAR-T and all subjects who provided written informed consent was included in the study, as previously described . The curClinical data were extracted retrospectively from electronic medical records, including demographics, baseline cardiac and oncologic risk factors, and baseline laboratory and transthoracic echocardiogram. Cardio-oncologists reviewed all electrocardiograms and transthoracic echocardiograms. Echocardiogram data was extracted through clinical reports. LV dimensions were calculated from parasternal long axis. LV ejection fraction was calculated through method-of-disc (MOD) method. LA volume was calculated through MOD method, indexed to body surface area. Data were collected and managed using REDCap electronic data management system hosted at Moffitt Cancer Center .Continuous variables were presented as mean ± standard deviation or median with interquartile range, depending on the normality of data using the Shapiro-Wilk normality test. Continuous variables were compared between groups using the student’s t-test or nonparametric comparison (Mann-Whitney test) depending on the normality of the data. Categorical data were compared using a chi-square test. Univariate logistic regression analyses were performed to report odds ratio and 90% confidence intervals (95% C.I.) of factors associated with cardiac events. Kaplan Meier survival analysis and a log-rank test were performed to determine differences in median overall survival durations of patients with and without cardiac events. A two-tailed p-value ≤0.05 was considered statistically significant. Statistical analysis was performed using R Software version 4.0.4 and GraphPad Prism (version 9) .(Table 1). Eleven patients developed adverse cardiac events (12.2%). One patient developed cardiomyopathy with reduced left ventricular ejection fraction and was later diagnosed with acute myocarditis based on cardiac MRI. Ten patients (11.1%) developed atrial fibrillation, one of whom had a history of atrial fibrillation prior to CAR-T therapy. A total of 26 patients (28.9%) underwent follow-up TTE at a median of 10 days [interquartile range of 6–23 days] after CAR-T.Ninety patients were included in this study. The cohort’s median age was 68 years, with 61.1% being male (Table ). Patients in the cardiac events group were older , had higher baseline creatinine  and a larger indexed left atrium volume , when compared to those who did not develop cardiac events (Table 1). After CAR-T therapy, the incidence of grade 2 or above CRS was similar in both groups  (Table 3). There was no difference in the rate of treatment of tocilizumab between those who did or did not develop cardiac events . There were eleven deaths (12.2%) one-year post-CAR-T. Of those, nine deaths were due to cancer progression, one due to CRS, and one due to pneumonia. The patients with cardiac events did not exhibit worse survival compared with patients without cardiac events .Baseline cardiac comorbidities were not significantly different in the cardiac events group, including prior heart failure, coronary artery disease, atrial arrhythmia, and chronic kidney disease Table . Patient(Table 3). There was no association between cardiac biomarkers performed at baseline or day 5 post-CAR-T and cardiac events in univariate logistic regression analysis. Of the 31 patients who developed CRS grade 2 or above, post-CAR-T TTE was performed in 17 patients (54.8%).The baseline troponin-I  and BNP  were similar between the two groups . After CAR-T therapy, the cardiac events group had a higher BNP level on day 5 . Day 5 troponin-I levels during hospitalization were not different between the two groups. Supplementary Tables 1–3). Inflammatory cytokine levels are summarized in Fig. A total of fifty-three patients  had serum testing of inflammatory cytokines at baseline and daily during hospitalization. Of the total eleven patients who developed cardiac events, nine had inflammatory cytokines tested. Baseline clinical characteristics, post-CAR-T clinical events and laboratory values were similar in patients who did and those who did not have inflammatory cytokine data , with 11.1% of patients experiencing atrial arrhythmia and one developing cardiomyopathy (1.1%). We identified that mostly clinical factors  were associated with cardiac events. However, cardiac (Troponin I and BNP) and inflammatory cytokine levels were not associated with cardiac events after CAR-T.Notably, our cohort had differences in the type of cardiac events compared to prior studies –8, 11. WIn our study, the baseline clinical factors, such as age and baseline creatinine were associated with adverse cardiac events similar to prior literature , 11, 12.We investigated cardiac biomarkers five days after CAR-T to assess the role of cardiac biomarkers in cardiotoxicities. Day 5 troponin-I was not elevated in those who developed cardiac events. Only one in ten patients who developed atrial fibrillation had elevated day 5 troponin I. Troponin-I is a traditional biomarker associated with new-onset cardiomyopathy, myocarditis, arrhythmia and cardiovascular death in cancer patients . In pediIn contrast, there was only a tendency for day 5 BNP levels association with cardiac events. The accentuated BNP level after CAR-T in the setting of cardiac events may be a reflection of baseline comorbidities  although not statistically significant due to low number. This may lead to sensitization to hemodynamic stress in cardiac events such as atrial fibrillation. Prior observational studies have shown inconsistent results regarding BNP levels and their association with cardiotoxicity , 22. WhiOf note, the current cohort had a lower incidence of high-grade CRS. Only two patients (2.2%) developed high-grade CRS with CRS grade 3 and 5 and no CRS grade 4. This is in comparison to an 8–22% incidence of high-grade CRS 3 or above in clinical trials and real-world commercial CAR-T use , 26. AltContrary to prior literature, adverse cardiac events did not occur more frequently in higher-grade CRS. To that end, we performed a comprehensive analysis of inflammatory cytokines to see if pro-inflammatory status plays a role in the pathophysiology of cardiac events. Several pro-inflammatory cytokines  were higher in the cardiac events group. This is in line with prior studies showing elevated IL-6 and IL-15 in patients with atrial fibrillation , 28. HowThere are several limitations to the current study. First, the study was a retrospective review of cardiac events. The method of detecting arrhythmia with abnormal heart rate or symptoms may underestimate the incidence of atrial fibrillation. However, the incidence of AF are comparable to other studies. To our knowledge, there is no study published that has performed continuous telemetry monitoring for all CAR-T patients. For other cardiac events, a close collaboration between the cardio-oncology and cellular immunotherapy teams was developed to evaluate for cardiotoxicities. Therefore, the chances of missing cardiotoxicity after CAR-T were low. Second, we have not performed daily measurements of cardiac biomarkers, which could have missed pre-clinical cardiac injury. Next, the current exploratory study had a small sample size and lower incidence of adverse cardiac events which did not allow for multivariate analysis. The strength of our study includes the measurement of inflammatory cytokines in the setting of CAR-T related cardiac events. Until now, the association between CRS and cardiac events were the only evidence for inflammation-induced cardiac events. Also, our study population represents the relatively recent management changes of CRS with earlier and aggressive use of tocilizumab. Although speculative, this may have changed the incidences of more severe cardiac events such as cardiomyopathy/ heart failure. Further studies are needed with larger cohort size to ascertain this hypothesis.In conclusion, adverse cardiac events, predominantly atrial fibrillation, occur commonly after CAR-T. The changes in serial inflammatory cytokine after CAR-T in the setting of adverse cardiac events suggests pro-inflammation as a pathophysiology and warrant further investigation.Below is the link to the electronic supplementary material.Supplementary Material 1