ST segment depression criteria and the prevalence of silent cardiac ischemia in hypertensives

The reported prevalence of silent cardiac ischemia as assessed by ambulatory electrocardiographic recording varies widely. The influence of the stringency of the analysis criteria has never been reported. We performed 24-hour, 12-lead ambulatory electrocardiographic recording in patients with hypertension but without proven coronary artery disease. The recordings were analyzed according to strict ST segment depression criteria adapted from the American College of Cardiology/American Heart Association guidelines and according to basic ST segment depression criteria adapted from studies with only concise descriptions of ambulatory electrocardiographic recording analysis. Also, we performed 24-hour ambulatory blood pressure monitoring. More than 4400 hours of ambulatory electrocardiographic recording and ambulatory blood pressure monitoring in 194 patients with hypertension were analyzed. Medication was withdrawn in 45% of the patients. The average systolic blood pressure during the day was 152+/-13 (mean+/-SD); diastolic blood pressure was 94+/-17 mm Hg. According to the basic ST segment depression criteria, we found a prevalence of silent ischemia of 11.3%, and with the strict criteria the prevalence was 5.2%. The patients who were considered positive according to the basic criteria but not according to the strict criteria (false-positive) in the majority of cases (58%) had depression of an elevated baseline ST segment. We found a lower prevalence of silent cardiac ischemia as assessed by ambulatory electrocardiographic recording than generally reported. The stringency of applied analysis criteria appear to play an important role in this outcome.