Symptoms of Patients With Silent Ischemia as Detected by Thallium Stress Testing: Symptom Score
Blood pressure was measured by mercury sphygmomanometry at the end of each 3-min stage, at intermediate intervals when indicated, at peak exercise, and at 1-min intervals during recovery. The ST segment deviation during exercise (that is, horizontal or downsloping depression or rarely elevation) was measured as the difference between the resting and peak exercise ST depression measured 0.08 s after the J point, expressed in millivolts. A positive response, according to conventional criteria, consisted >1.0 mV of horizontal or downsloping depression at any time during the test or the recovery phase of the test. Individuals with a left bundle branch block pattern, receiving digoxin, or those not meeting criteria for a positive test yet not achieving >85 percent of maximal predicted heart rate were considered to have had a nondiagnostic ECG response.
A dose of 2 to 2.5 mCi of thallium-201 chloride was administered intravenously at peak exercise and exercise was continued for 45 to 60 s after injection. Myocardial images were obtained at 6 to 10 min and repeated at 3 to 5 h after the test. Imaging was performed in the anterior, 45° left anterior oblique and 70° left anterior oblique views with 10-min acquisitions per view. A small field-of-view gamma camera was used, equipped with 0.65-cm-thick sodium iodide crystal and 37 photomultiplier tubes. All images were acquired and stored on a computer. Images were interpreted visually from the computer screen. Immediate postexercise images were inspected for regions of decreased uptake. Ischemia was considered to be present if such regions demonstrated increased activity on the delayed image. Thallium studies were graded from 0 to 3:0, no defect; 1, a nonreversible defect; 2, a reversible defect; and 3, both reversible and nonreversible defects. Also, pulmonary lung activity was assessed as to whether it was normal or increased. canadian health & care mall
On completing the exercise test, individuals were requested to indicate on a questionnaire whether they had experienced any of ten symptoms and if so, to grade the discomfit as mild, moderate, or severe. The symptoms listed were chest pains, back pains, jaw or arm pains, breathlessness, tiredness, weakness, dizziness, lightheadedness, headache, and leg discomfort. A questionnaire in Spanish was used for those individuals who were Spanish speaking. Each symptom was scored as 0 for not experienced, 1 mild, 2 moderate, and 3 severe. All data were stored and analyzed using software (SPSS/PC+ 4.0.1) for a desk computer; p<0.05 was considered as statistically significant. All variables were analyzed to determine their distribution using the Kolmogorov-Smirnov test. Continuous variables that were normally distributed were analyzed using the t test and expressed as the mean±SEM. The Mann-Whitney U test was used to analyze nonparametric variables. Logistic regression was used for a multivariate analysis comparing the silent ischemia and angina groups.