Introduction: CAR T-cell therapy has been reported to have cardiovascular (CV) adverse effects mostly in context of cytokine reconstitution syndrome (CRS). Although pathophysiology of CAR T-cell cardiotoxicity (CTCC) is not fully understood, it is thought to be IL-6 mediated which has been implicated as a mediator of myocardial depression in infectious and inflammatory states. Another mechanism is direct cardiotoxicity from potential cross-reactivity with unrelated peptides expressed by normal tissue. We present a case of Takotsubo cardiomyopathy following CAR T cells. Case: 61 year old male with h/o Waldenstrom's macroglobulinemia, DMT2, HLD was admitted for CAR T cell therapy. Following infusion, he developed chills, diaphoresis, tachypnea, tachycardia, chest tightness lasting several hours. EKG had dynamic ST depressions in inferolateral leads with elevated hstroponin (6000 pg/ml). Despite severe pancytopenia, heparin was started for acute coronary syndrome. Pain resolved with morphine and he received tocilizumab for CRS. Echo showed a mid-cavitary variant of Takotsubo involving right and left ventricles with depressed systolic function (LVEF 30-35%; Image). Coronary angiogram was deferred due to bleeding risk. Repeat echo in 2 days showed persistent mid-cavity hypokinesis with slight improvement in LVEF (40%) after initiating beta blocker. The temporal relation of acute mid-cavity dysfunction to CAR T-cells indicates most likely CTCC. Heparin was stopped and he was managed conservatively with plan to reassess LVEF in 2 months. Conclusion: Patients undergoing CAR T-cell therapy should be assessed for CV symptoms using biomarkers and imaging for early detection of cardiotoxicity and prompt initiation of supportive treatment. We present a case of acute mid-cavity left ventricular dysfunction (a Tako-tsubo variant) that was temporally related to CAR T cell infusion. Further studies are needed to determine the frequency of this acute form of CTCC.