This is a meta-analysis involving seven studies with data from a total of 4810 patients. The authors found no difference between the continuous or intermittent ADT treatments in the incidence of cardiovascular events or problems with blood clots. They did, though, find a very slight reduction in the number of death due to cardiovascular events in the men who got ADT intermittently.
It is worth noting that the patients in the study were all on LHRH agonists (like Lupron or Zoladex). None of the patients received a LHRH antagonist (like Degarelix) which may have a lower risk of serious cardiovascular events.
Jin C, Fan Y, Meng Y, Shen C, Wang Y, Hu S, Cui C, Xu T, Yu W, Jin J. 2016. A meta-analysis of cardiovascular events in intermittent androgen-deprivation therapy versus continuous androgen-deprivation therapy for prostate cancer patients. Prostate Cancer Prostatic Dis. [Epub ahead of print] 6 September 2016. www.ncbi.nlm.nih.gov/pubmed/27595915