Risk factors for exercise-induced silent myocardial ischemia in healthy volunteers

This study determined the risk factors for exercise-induced silent ischemia (SI) in 281 apparently healthy volunteers aged 40 to 87 years and compared their risk factor profiles with those of 132 patients with overt coronary artery disease (CAD). SI (concordant exercise-induced asymptomatic ST-segment depression on electrocardiography and perfusion defects on tomographic thallium-201 scintigraphy) was detected in 37 of 225 men (16%), versus 2 of 56 women (4%, p < 0.05). The prevalence of SI increased with age from 6% in men aged < 55 years to 18% in men aged 55 to 70 years, and to 25% in men aged > 70 years (p < 0.001). Compared with the 118 men with concordant normal exercise electrocardiogram and thallium scan (normals), men with SI were older (p < 0.001), and had a higher waist-to-hip ratio (p < 0.005), higher plasma triglyceride levels (p < 0.001), and lower high-density lipoprotein (HDL) cholesterol levels (p < 0.001). In stepwise logistic regression analysis, age, waist-to-hip ratio, and HDL levels were independent predictors of SI in men. Compared with 108 men with overt CAD, men with SI were younger (67 +/- 2 vs 73 +/- 1 years, p < 0.001) but had similar plasma lipids and waist-to-hip ratio. Thus, older age, male gender, abdominal obesity, and reduced HDL levels--all well-established risk factors for overt CAD--were risk factors for exercise-induced SI in these asymptomatic volunteers.