Ondansetron-induced cardiac arrest and cardiomyopathy with successful reversal: a case report

Ondansetron, a 5-hydroxytryptamine 3 (5-HT3) receptor antagonist, is used as an antiemetic medication for the management of nausea and vomiting. Since ondansetron may cause QT-interval prolongation, the Food and Drug Administration (FDA) issued a warning about its use, particularly in individuals who are at risk for cardiac arrhythmias. We report a case of cardiac arrest and cardiomyopathy following a single intravenous (IV) ondansetron dose with successful complete recovery after taking proper clinical interventions. Our findings would therefore raise awareness to take preventive measures upon administering ondansetron, whether in patients who are medically free or those who are at risk for developing cardiac arrhythmias.

We report a 43-year-old female patient with a negative medical and psycho-social history who had cardiac arrest due to ondansetron administration, along with hypomagnesemia, hypocalcemia, and lower-limit serum potassium level, which resulted in ventricular fibrillation, torsade de pointes, and cardiomyopathy. We also raised the suspicion of anaphylaxis to ondansetron, where certain investigations were done accordingly. The patient required cardiopulmonary resuscitation (CPR) and intensive care unit (ICU) admission for further management of electrolyte imbalance, left ventricular (LV) dysfunction, and suspected anaphylaxis. Certain interventions were done, which resulted in significant improvement and complete patient recovery.

Our case emphasizes the need to be cautious when administering ondansetron, and electrolyte imbalance is considered a risk factor for cardiac arrhythmias following ondansetron administration. It is then imperative that clinicians consider ondansetron-associated cardiac arrest and cardiomyopathy, take preventive measures, and remain vigilant for any unfavorable incidents that may arise.