Do you routinely check an ECG in the ambulatory setting in patients without a cardiac history when starting a medication that can potentially prolong QTC?

I do not. Typically, the drugs I use that could be QTc-prolonging are short-term medications and are low dose. However, if there is a potential for longer use (>2-4 weeks) or dosages that are not typical, I will typically err on the side of caution and check an ECG prior to committing them to extend...