The Q-T ratio as a guide to the exercise test in the digitalized subject.

Ten normal digitalized snbjem and six patients with isrhemic h e m disease taking digitalis were studied to determine the otility of the Q-T mtin as a pob sihle guide to differentiating a positive and negative exercise test in the presence of digitalis. A striking decreare in the Q-T ratio in normal digitalized mhjeftr was seen with exercise. Digitalized patienh with ischemic h e m disease, bowever, responded with a uniform lengthening of the Q-T ratio with exercise. Thus, in this mall group of patients, it appears that shortening of the Q-T ratio, in the presence of ST segment changes with exercise in the digitalized subject favors a false positive test due to the drug, whereas lengthening of the Q-T ratio favors a truly positive fed unrelated to the di-ug.