Canceling a surgery because you're not comfortable w/ pt's hx.

just today we had a patient that was found to have undiagnosed/untreated HTN.
BP was around 180-200/80-90s. even though current literature states postponing elective surgery with diastolic >110, this pt was undiagnosed and untreated, so it was decided to consult primary care and cardiology, and postpone surgery.
some will argue why not tx BP and go ahead. even more current literature (not published yet) states that treating patients with beta blockers day of surgery (and never tx'd with BB before) actually poses a greater risk/outcome of morbidity and mortality.
so, moral of the story, as previously stated, the clinical picture needs to be your guide. and if it is a good enough argument, chances are the surgeon will go along with it, unless the surgeon says it's an emergent surgery, then you tighten your sphincter and proceed accordingly.

How often does the situation arise that you look at a patient's chart and decide that, because of the patient's history, you are not comfortable proceeding with the surgery? Does the surgeon usually agree with you or can there be a lot of conflict? I realize that CRNAs, like any health care provider, must be a patient advocate first and foremost but in this era of get 'em in and get 'em out/restaurant-style health care (at least in busier areas) how much conflict arises between anesthesia providers and surgeons over opinions of potential patient instabilty during a surgery?

This happens from time to time. But you cannot cancel a case on a "feeling" you must remember that the most common place that a CRNA will have such autonomy is a rural hospital. There are usually only a few surgeons at these hospitals and they are often the biggest revenue generators so if you say no you need a reason.
Remember surgeons want to cut and hospitals want to make money so pick your battles cause if you do it to often no one will appreciate it.