Would you withhold a fluoropyrimidine in a newly diagnosed patient with metastatic colon cancer who had a STEMI and new diagnosis of ischemic cardiomyopathy within the last 3 months?

While the reported incidence of cardiac events is noted above, in practice this is far less likely as a clinical event. Also, as noted, vasospasm is more likely in the younger patient, generally without atherosclerotic heart disease.

In the patient with a STEMI, it is most likely safe to use infusi...

This patient is at high risk for coronary vasospasm as you have surmised. I think obtaining an NGS panel is critical here. If KRAS wild type or BRAF mutated, I would definitely start with non-5FU regimens. If those are not options or you can’t wait for NGS to result to start treatment you can consid...

Cardiotoxicity related to 5-FU administration is a poorly understood but relatively common clinical entity. The reported incidence of 5-FU-associated cardiotoxicity can be from as low as 1% to as high as 18% due to differences in the sample population, definitions of 5-FU-associated cardiotoxicity, ...