Exercise-induced ST depression in an asymptomatic population without coronary artery disease

Objectives. Exercise electrocardiogram (ExECG) in low risk populations frequently generates false positive ST depression. We aimed to characterize factors that are associated with exercise-induced ST depression in asymptomatic men without coronary artery disease. Design. Cycle ergometer exercise tests from 509 male firefighters without imaging proof of significant coronary artery disease were analysed. Analysed test data included heart rate at rest before exercise, and workload, blood pressure, heart rate, ST depression and ST segment slope at peak exercise. ST depression of >0.1 mV was considered significant (STdep). With a mean follow-up of 6.1 ± 1.7 years, medical records were reviewed for cardiovascular diagnoses, hyperlipidemia and diabetes. Logistic regression analysis was used for risk assessment. Results. In total, 22% had STdep in ≥1 lead. Subjects with STdep were older than those with normal ExECG (p < .001). Downsloping STdep was more common in extremity leads (9%) than in precordial leads (2%). STdep was categorized according to location (precordial/extremity) and slope direction into eight categories. Larger age-adjusted heart rate increase predicted STdep in seven categories (p < .05). Age-adjusted peak heart rate correlated with STdep in five categories, predominantly where the ST slope was positive. Peak blood pressure and exercise capacity were both associated with STdep in few categories. We found no association between STdep and hypertension, hyperlipidemia or diabetes (all p > .05). Conclusions. In asymptomatic men with a physically demanding occupation and no coronary artery disease, both age and heart rate response were associated with ST depression, whereas common cardiovascular risk factors, blood pressure response and exercise capacity were not.