No it is not a common reaction. From Dr Koop's site:
"Some quinolones, including levofloxacin, have been associated with prolongation of the QT interval on the electrocardiogram and infrequent cases of arrhythmia. During post-marketing surveillance, rare cases of torsades de pointes have been reported in patients taking levofloxacin. These reports generally involved patients with concurrent medical con-ditions or concomitant medications that may have been contributory.
The risk of arrhythmias may be reduced by avoiding concurrent use with other drugs that prolong the QT interval including class Ia or class III antiarrhythmic agents; in addition, use of levofloxacin in the presence of risk factors for torsades de pointes such as hypokalemia, significant bradycardia, and cardiomyopathy should be avoided. "
As a rule, I do not prescribe Levaquin for someone with a known arrhythmia and/or profound bradycardia. I have not seen Levaquin cause arrhythmia, but rather not do so also - lol.
Please don't worry about this. Yes, you should know drug interactions but this is a small percentage of cases where this develops. As long as you know it is a possibility and you have taken the appropriate precautions, like telemetry monitoring, than you have covered your bases.
Good luck and take care.