Symptoms of Patients With Silent Ischemia as Detected by Thallium Stress Testing: Method


Symptoms of Patients With Silent Ischemia as Detected by Thallium Stress Testing: MethodThe occurrence of myocardial ischemia without chest pains has been referred to as silent (myocardial) ischemia. Because myocardial ischemia produces a complex array of hemodynamic and neurohu-moral effects, even when pain is not experienced, nonanginal symptoms might be expected. Previous studies of silent ischemia have focused on the significance, mechanisms, and prognostic implications of this disorder.” It would be of interest to know also whether individuals with myocardial ischemia not having chest pains experience other sensations that might serve as surrogate warnings. Symptoms resulting from myocardial ischemia not perceived as angina pectoris could be termed “anginal equivalents.” Patients undergoing stress testing might be a suitable cohort for identifying “anginal equivalents’ The purpose of this study was to determine the symptoms of individuals who have evidence of myocardial ischemia but do not experience chest, arm, back, or jaw pains. In this study, myocardial ischemia was denoted by scintigraphic or electrocardiographic changes occurring on thallium stress testing. Symptoms occurring during the test were assessed by a questionnaire completed by the patient immediately following cessation of the study.

From January 1991 through April 1992, a database was accumulated of individuals who had undergone thallium stress testing and had completed questionnaires before the test relating to clinical considerations and another after the test in which symptoms occurring during the test were quantified. Data were collected from 294 consecutive individuals who had been tested and completed both questionnaires. The angiographic findings of those in this group who had coronary arteriography during this period were also reviewed. (Severity was scored as 0 for patent arteries, 1 for single artery not involving left anterior descending [LAD], 2 for single artery involving LAD, 3 for double artery not involving LAD, 4 for double artery involving LAD, 5 for triple artery, and 6 for left main artery; stenoses > than 50 percent were considered significant.) All individuals underwent a standard Bruce protocol treadmill exercise test. Twelve-lead electrocardiograms (ECG) were recorded before exercise, at the end of each exercise stage, at peak exercise, and at 1-min intervals during recovery, until the ECG had returned to baseline values. During exercise, three leads (2, aVF, and V5) were continuously monitored. Time of onset and resolution of ST segment depression and symptoms were also noted. End points for the test were the development of exertion limiting symptoms (chest pain, fatigue, dyspnea, or claudication) cardiac arrhythmias, such as frequent ventricular couplets or ventricular tachycardia, a decrease of systolic pressure >10 mm Hg from pretest value, and/ or >2 mV of horizontal depression.