QRS Score: a composite index of exercise-induced changes in the Q, R, and S waves during exercise stress testing in
1Division of Cardiology, First Department of Medicine, University of Pecs, School of Medicine, Ifjusag ut 13, Pecs, H-7643, Hungary.
Background:
To detect ischemic heart disease, the exercise-induced ST-segment displacement is the most frequently used ECG parameter. However, the value of this marker was proven to be limited with varying sensitivity and specificity. A new parameter, called QRS score, emerged to improve the efficacy of exercise testing.
Methods:
Our study aimed at evaluating the diagnostic value of QRS score in ischemic heart disease, investigating males and females separately, and examining the effects of heart rate and antiischemic medication. QRS score and cumulative ST depression were calculated in 212 patients and correlated to the findings of the stress myocardial perfusion SPECT (197 subjects) or coronary angiography (54 subjects).
Results:
An inverse correlation could be found between the QRS score and the results of myocardial SPECT and coronary angiography in the whole population, especially in males; females did not show a significant relationship. In patients with conclusive tests (achieving 85% of the maximal predicted heart rate) QRS score correlated significantly with the results of the stress myocardial perfusion SPECT and coronary angiography. The sensitivity, specificity, and validity of the QRS score surpassed those of the cumulative ST depression in the entire population as well as in patients with conclusive tests. The antiischemic medication did not affect correlation values.
Conclusion:
QRS score was significantly related to the extent of myocardial ischemia and the severity of coronary heart disease, thus along with the analysis of ST-segment displacement may contribute to the more precise evaluation of exercise testing.
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