What is your typical approach to the use of beta blockers in the setting of recent cocaine use amongst patients presenting with cocaine-related MI, arrhythmias, or new-onset heart failure?   

I favor using or continuing non-selective beta-blockers in patients presenting with acute cardiac manifestations of recent cocaine use. My preferred agent in this setting is carvedilol. 

BB withdrawal has similar manifestations to cocaine induced alpha receptor activation (minus tachycardia).  So continued BB use would be advisable.  BB with alpha receptor effects like carvedilol or labetalol are reasonable options in this setting.