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[Predictive value of the ergometric test stress parameters for myocardial ischemia according to SPECT thallium-201
1Centro Cardiovascular, Hospital Clínico, Universidad de Chile, Santiago, Chile.
Background:
Exercise EKG is used as the test of choice in the diagnosis of coronary artery disease. Classical parameters are angor and ST depression representing myocardial ischemia.
Aim:
To correlate exercise EKG parameters with SPECT 201Thallium to know their likelihood ratios for ischemia.
Patients And Methods:
Two hundred seventy four patients (171 men), aged 58 years old as a mean, were studied. Of these, 23% had a prior myocardial infarction. The likelihood ratios for the presence of ischemia of ST depression, failure to increase blood systolic pressure, the presence of angor and its duration during stress testing were calculated according to the results of SPECT 201Thallium. Seventy one patients were also subjected to a coronary angiography.
Results:
Among men, likelihood ratios for the presence of angor, failure to increase systolic pressure, ST alterations and duration of angor were 6.9, 6.15, 1.77 and 1.27 respectively. Among women, the figures were 5.45, 1.77, 0.58 and 1.4 respectively. The diagnostic accuracy of SPECT 201Thallium, when correlated with the results of coronary angiography, was 85%.
Conclusions:
Among men, the best exercise EKG predictors for myocardial ischemia were the failure to increase systolic blood pressure and the presence of angor. Among women the only significant predictor was the presence of angor.