THE DIAGNOSTIC VALUE OF ELECTROCARDIOGRAPHIC EXERCISE STRESS TESTING FOR CORONARY ARTERY DISEASE
Purpose: Evaluation of the diagnostic value of of electrocardiographic ( ECG) stress testing in obstructive coronary artery disease (CAD) in the modern era of cardiology.
Methods: We have performed a retrospective study on 404 patients with chest pain suggestive for angina and with no personal history of ischaemic heart disease, which have performed a treadmill exercise stress testing and after that a coronarography, from October 2008 to January 2013.The coronarography was done in a period of days until two months after the stress test. A positive test was defined as >=1 mm horizontal or downsloping ST-segment depression or >=1.5 mm slowly upsloping depression (the slope was < 1mV/s). A significant lesion on coronarography was defined as >=70% stenosis.
Results: From 404 patients, 254 were men (635) and the average age was 59.3 years +/- 9 years. Hypertension was found in 80.7% (326 patients), diabetes in 23.2% (94 patients), 48.5 % were smokers (196 patients), 82.1% had dyslipidemia (332 patients) and 30.7% were overweight (124 patients). A positive stress test was found in 285 patients and 186 had significant stenosis on coronarography. The rest of 119 patients had either a negative stress test, an equivocal one or inconclusive (the inability to reach 85% of the target heart rate, and without any ST segment alterations). At the coronarography we found significant lesions in 32 patients (26.9%) from the group with negative, equivocal or inconclusive stress testing.
The sensitivity of the test was 85.3% and the specificity 46.7%. The positive predictive value was 65.2% and the negative predictive value was 73.1%. The degree of ST segment changes showed a correlation with the degree of stenosis. No correlation was found between the ECG territory were the ST depression appeared and the affected vessel. The time of exercise is correlated with the age of the patient.
Conclusions: In modern era where imagistic stress testing seems to have a better sensitivity, the old fashioned electrocardiographic stress test continues to have a good sensitivity and remains, due to the larger accessibility and lower cost compared with other techniques (stress echography, stress SPECT, myocardial perfusion imaging) the first option in the diagnostic algorithm of coronary artery disease.