Introduction:
Cardiac complications are rare but a potentially serious side effect of oncological therapies. While the latest European Society of Cardiology guidelines for cardio-oncology provide recommendations, recent advances in cancer treatment pose additional risks of cardiotoxicity. According to current guidelines, treatment with cyclophosphamide, doxorubicin, vincristine and prednisolone in combination with obinutuzumab (OBi-CHOP) is one of the first-line treatment options for follicular lymphoma (FL) depending on clinical stage and conditions.
Case report:
A 37-year-old woman with FL (Ann Arbor classification stage III) received 6 cycles of Obi-CHOP. 371 days after the last cycle of CHOP, during maintenance therapy with Obinutuzumab, the patient developed dyspnea and fever. Positron emission tomography–computed tomography showed no progression of lymphoma. Electrocardiography revealed a third-degree atrioventricular (AV) block, requiring urgent dual-chamber pacemaker (PM) implantation. After exclusion of other possible causes, pre-procedural cardiac magnetic resonance imaging (C-MRI) demonstrated diffuse myocardial fibrosis without late gadolinium enhancement. These findings were consistent with medication-induced (toxic) myocardial changes likely related to the initial chemotherapy. The ejection fraction remained normal. During the first 7 weeks of PM follow-up, ventricular pacing was less than 1%, suggesting recovery. In a follow-up MRI at week 8, there was interim normalization of T1/T2 mapping with complete regression of the prior findings despite ongoing therapy with Obinutuzumab.
Discussion:
We present an extremely rare case of a patient who developed a third-degree AV block during treatment with Obi-CHOP. Obinutuzumab is an anti-CD20 monoclonal antibody that, in rare cases, can lead to cardiac complications. In the literature, AV block as cardiac complication during ongoing chemotherapy has only been documented once, during infusion of doxorubicin, which is well known for its cardiotoxicity.
We, however, suspect that the doxorubicin therapy was too remote in time to have direct inflammatory effects consistent with myocarditis and suspect the myocarditis to be related to obinutuzumab. Notably, the myocarditis resolved spontaneously despite ongoing obinutuzumab therapy, suggesting a short, self-limiting course possibly triggered by the current treatment.
Conclusion:
Our findings suggest that regular cardiologic monitoring during cancer therapy should not be limited to high-risk patients. With proper cardiology care and regular diagnostic follow-up, it is possible to continue oncologic treatment without interruptions.
