Lack of ouabain effect on pacing-induced myocardial ischemia in patients with coronary artery disease

Sixteen patients with significant two and three vessel coronary artery disease but without clinical congestive heart failure were studied during rapid atrial pacing before and after infusion of 0.015 mg/kg of ouabain. Seven patients with a decreased (less than 50 percent) election fraction and nine patients with a normal election fraction had a significant ( P < 0.05) increase in resting arterial systolic pressure after the administration of ouabain. However, resting values for coronary sinus flow, coronary vascular resistance, myocardial oxygen consumption and myocardial lactate extraction did not change significantly in either group. During pacing, patients with a decreased ejection fraction demonstrated more ischemia than patients with a normal ejection fraction; however, the administration of ouabain did not significantly alter pacing-related changes in coronary sinus flow, myocardial oxygen consumption, myocardial lactate extraction, ischemic electrocardiographic changes or onset of chest pain in either group. The administration of ouabain has a negligible effect on coronary hemodynamics, myocardial metabolism or clinical signs of ischemia in patients with coronary artery disease with normal or abnormal left ventricular function.