Some of chemotherapeutic agents (e.g., mitoxantrone) may suppress the activity of inwardly rectifying K(+) channels expressed in heart cells. Consequently, their overdose may lead to cardiac arrhythmia to some extent.

https://www.karger.com/Article/Abstract/341449

As compared with congestive heart failure, cardiac arrhythmia causes rarely after the high-dose administration of cyclophosphamide?

High dose of cyclophosphamide causes prolonged QT on ecg, which will further leads to torsades de pointes.

Chronic administeration of cyclophosphamide causes cardiomyopathy ( dilated cardiomyopathy).

Suppressive activity by any of chemotherapeutic agents of inwardly rectifying potassium channels in heart cells might potentially lead to cardiac arrhythmia.

http://www.physiology.org/doi/abs/10.1152/ajpheart.00393.2006?url_ver=Z39.88-003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed

Hi Go,, high dose of cyclophosmamide rarely can cause Myocarditis and heart failure. Cardiac side effect are common with doxorubicin but high dose cyclophosmamide can rarely also cause Myocarditis and heart failure. lt is usually occur within 10days of chemotherapy and does not occur because of cumulative effect. Cardiac side effect are because of Endothelial damage and leakage of fibrin and fluids in interstitium. Histopathology usually reveals acute pericarditis and haemmorragic Myocarditis which may be fatal. Congestive heart failure is the common manifestation and arrhythmia is rare. Following link might help you ..thanks

Hi Go,, continuing the discussion pulmonary toxicity of cyclophosmamide, two types of toxicity seen. One acute onset interstitial pneumonitis like that respond to cessation of cyclophosmamide therapy. Another one is delayed bilateral pulmonary fibrosis and pulmonary arterial hypertension that does not respond to cessation of cyclophosmamide therapy and relatively poor prognosis ..thanks

Hi Go,, continuing the discussion,cyclophosphamide has been reported to cause cardiac arrhythmia in the form of atrial fibrillation and transient high grade AV block... Thanks

Dear Dr. Biswajit Majumder .

Thank you for your kind discussion!

Given that cyclophosphamide has been reported to cause cardiac arrhythmia in the form of atrial fibrillation and transient high grade AV block, we oncologists should be more careful to the ECG monitoring.

Sincerely

Go

ECG monitoring is getting important in patients treated with chemotherapeutic agents. Most of young physician appear to neglect or to ignore such simple device.