Angina: current approaches to diagnosis, drug therapy, and surgical referral.

An abnormal resting ST segment renders the stress ECG impossible to interpret. Therefore, one must substitute a radionuclide stress evaluation in the presence of digitalis, left bundle-branch block, left ventricular hypertrophy, a paced rhythm, or any other condition that would cause abnormal baseline ST segments. All these are more common in the elderly. Beta-blocker therapy is useful in patients with demand-related ischemia because it decreases two of the major determinants of myocardial oxygen demand: heart rate and contractility. Propranolol, timolol, and metoprolol have been shown to decrease the reinfarction and mortality rates in patients who have had an infarction.