[Sinus node function of ischemic heart disease patients with chronotropic incompetence].

Forty-five (17.6%) of 256 coronary patients showed inadequately small heart rate augmentation in response to rationed exercise ("chronotropic incompetence"). To assess their sinoatrial node function, esophageal atrial stimulation was done in all patients before and after drug-induced vegetative block, and the adjusted sinoatrial node function time and sinoatrial conduction time were determined. Electrophysiological evidence suggests that "chronotropic incompetence" is in most cases determined by abnormal sinoatrial rhythm. Rationed exercise testing can be used as a screening test for latent weak sinoatrial node syndrome in coronary patients.