The incidence of non-fatal myocardial infarction among 4830 vasectomised men was 0.9 cases per 1000 man-years during 24 420 man-years of observation. This was slightly lower than the rate in 24 150 non-vasectomised men, matched with a vasectomised man for calendar year of birth and duration of observation. Review of medical records for a matched sample of study subjects indicated no measurable confounding by important cardiac risk factors.
PIP: This study was undertaken to investigate the risk of nonfatal myocardial infarction among vasectomized men. Among a group of 4830 vasectoized men there were 23 first time infarctions, giving a rate of 0.90 infarction/1000 man-years at risk. There were 120 first time infarctions in a control group of nonvasectomized men, giving a rate of 1.0 infarctions/1000 man-years at risk. Incidence rate rose with time in both groups as the men became older, and obesity and smoking were both associated with infarction in both groups. The lack of a vasectomy-related effect was present throughout an observation period of 7 years after vasectomy. Some laboratory data gathered on monkeys suggest that there may be long-term risks not yet manifested in human populations. Long-term studies are needed to obtain more information on the subject.