Situation: A 45-year-old man with bulky diffuse large B-cell lymphoma is admitted for his first cycle of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone. Three weeks later, he returns for cycle 2. His results are: Absolute neutrophil count: 2,600/mm³ (1,500–8,000) Platelet count: 180,000/mm³ (150,000–400,000) Left ventricular ejection fraction: 40% (normal 55–70%; his baseline 62%) He has no fever and no signs of bleeding. What should the nurse do before the drugs are given?

His blood counts have recovered and are within normal limits, so the marrow does not prevent treatment. However, his ejection fraction has fallen from 62% to 40%, below normal. Doxorubicin causes cumulative cardiotoxicity and is avoided when ejection fraction is reduced, so the nurse holds it and reports the result before the cycle proceeds.

His blood counts have recovered and are within normal limits, so the marrow does not prevent treatment. However, his ejection fraction has fallen from 62% to 40%, below normal. Doxorubicin causes cumulative cardiotoxicity and is avoided when ejection fraction is reduced, so the nurse holds it and reports the result before the cycle proceeds.

The absolute neutrophil count of 2,600/mm³ and platelet count of 180,000/mm³ are both within the reference ranges, indicating adequate bone marrow recovery after cycle 1. This means the hematologic criteria for proceeding with chemotherapy are met. The critical abnormality is the left ventricular ejection fraction, which has dropped from a baseline of 62% to 40%, falling below the normal threshold of 55%.

Doxorubicin is an anthracycline that exerts its antitumor effect through topoisomerase II inhibition and free radical generation, but the same oxidative stress damages cardiomyocytes through mitochondrial dysfunction and iron-mediated reactive oxygen species formation. This injury is cumulative and dose-dependent, and once left ventricular systolic function declines, further exposure can precipitate irreversible heart failure. In this patient, the ejection fraction decline from 62% to 40% after only one cycle signals early but clinically significant cardiotoxicity.

The decision to hold doxorubicin rather than cyclophosphamide reflects the distinct toxicity profiles of the R-CHOP components. Cyclophosphamide is primarily associated with hemorrhagic cystitis and bone marrow suppression, not direct myocardial depression. Vincristine causes peripheral neuropathy, and prednisone contributes to hyperglycemia and immunosuppression. None of these agents explains the observed drop in ejection fraction. The anthracycline component is the clear culprit.

Evidence from DLBCL cohorts reinforces the clinical significance of this finding. In one multicenter study, the cumulative incidence of anthracycline-induced cardiotoxicity was 12.2% at 1 year and 17.5% at 5 years, with a median time to development of 6.4 months ^[2]. Although this patient developed cardiotoxicity earlier than the median, the trajectory is consistent with the known risk. Furthermore, research comparing R-CHOP with the doxorubicin-free regimen R-CEOP in patients with cardiovascular comorbidities demonstrated that substituting etoposide for doxorubicin is a recognized strategy when anthracycline exposure is unsafe . This supports the principle that doxorubicin should be withheld when cardiac function is compromised.

Electrocardiographic changes also accompany anthracycline exposure. In one retrospective analysis of DLBCL patients receiving anthracycline-based chemotherapy, the incidence of abnormal ECG findings increased from 36.8% at baseline to 48.7% after treatment . While the current question focuses on ejection fraction rather than ECG, the broader point is that anthracyclines produce measurable cardiac injury across multiple modalities, and monitoring must be proactive.

Watch out! A common error is to assume that because blood counts have recovered, the entire cycle can proceed without modification. Hematologic recovery does not equal cardiac safety. Each organ system affected by chemotherapy requires independent assessment before drug administration.

Key point! The nurse's responsibility is to recognize that a decline in ejection fraction below normal in a patient receiving doxorubicin is a contraindication to further anthracycline exposure until the prescriber evaluates the result and adjusts the regimen. Holding the doxorubicin and reporting the finding is the correct and safest action.

In elderly DLBCL patients, risk factors for anthracycline cardiotoxicity include pre-existing cardiovascular disease and cumulative anthracycline dose, and careful monitoring is emphasized because cardiotoxicity may be irreversible once established . Although this patient is 45 years old and not elderly, the principle of early detection and dose modification applies universally.

The nurse should also anticipate that the prescriber may order a repeat echocardiogram, cardiology consultation, or a change to a non-anthracycline regimen such as R-CEOP, depending on the clinical context and the patient's overall treatment goals . The immediate nursing action, however, is to hold the doxorubicin and report the ejection fraction decline before any drugs are given.