Swiss Interventional Study on Silent Ischemia (SWISSI 1)

Although there is still controversy regarding why ischemic episodes are symptomatic in some patients and completely asymptomatic in others, it is now widely accepted that silent ischemia, like symptomatic episodes, negatively affects prognosis. Silent ischemia may occur in totally asymptomatic patients without (type I) or with a history (type II) of an ischemic cardiac event and coexists with symptomatic episodes in many patients (type III). However, there is a lack of data on the prognostic importance of silent ischemia in totally asymptomatic subjects without history of coronary artery disease (CAD), i.e. silent ischemia type I, and, particularly, on a possible benefit of medical therapy in such patients. Reasons lie in the difficulty to identify such patients and their expected low event rates implying that large patient populations and/or long follow-up periods would be necessary to come to definite conclusions. Still, to address this problem, we perform SWISSI 1 which includes totally asymptomatic subjects older than 40 years of age without any history of CAD but one cardiovascular risk factor with documented silent ischemia. They are randomized to open antianginal drug therapy and risk factor control versus only risk factor management and followed up for ≥ 10 years.