Zithromax Z-Pak Causes Fatal Heart Rhythms By Staff on March 21, 2013 Posted in Zithromax Z-Pak CNN reports that the popular antibiotic drug azithromycin, marked under the brand name Zithromaz Z-Pak, can cause fatal arrhythmia in its users. Read more on how Zithromax Z-Pak causes cardiovascular death by reading the CNN report.