Exercise testing in suspected coronary artery disease

Addition of the duration of ST segment depression to Duke treadmill score for diagnostic accuracy of exercise electrocardiography to predict obstructive coronary artery disease

INTRODUCTION

Exercise electrocardiography (EET) is a safe and cost-effective method to predict the presence, prognosis, and severity of coronary artery disease (CAD). Various score models have been developed to increase predictive power of EET. In this study, we aimed to evaluate whether adding ST depression duration could have an effect on increasing the value of Duke treadmill score (DTS) in predicting obstructive CAD.

METHODS

In this single centred, cross-sectional study, we evaluated a total of 258 patients who presented with a complaint of chest pain and undergone coronary angiogram in result of a positive EET. DTS was calculated for all the patients. The new score-revised DTS- was calculated by adding total ST depression time to classical DS parameters. We compared area under the curve (AUC) of DTS and revised DTS by Delongi method.

RESULTS

Mean age of the group was 58.43 ± 9.37, and 37.2% (n = 96) were female. Mean total ST-depression duration was 171.72 ± 91.43 msec in normal artery group,241.54 ± 118.11 msec in non-obstructive CAD group, and 281.26 ± 113.64 in obstructive CAD group.ST-depression duration in both exercise and recovery, and total ST depression duration were significantly higher in obstructive CAD group than non-obstructive and normal artery groups (p = 0.024, p = 0.01, p < 0.01, and p < 0.01, respectively). Revised DTS had significantly higher predictive value of obstructive CAD compared to classical DS (AUC (95%CI): 0.744 vs. 0.626, p < 0.001). The AUC of DS was significantly lower than the new score (z-score:3.274, p = 0.011).

CONCLUSION

In conclusion, adding ST depression duration to DTS calculation is increasing the discriminative value of DTS to predict obstructive CAD. Benefits of EET within the context of the management of CAD is well-known, hence, it is clear that physicians may use revised DTS.

Repeated testing. An overview and analysis

Physicians often obtain the same test over and over again. This article first considers screening tests, such as mammographic screening for breast cancer, and describes several proposals for finding the interval that best balances cost, harms, and benefits. The same principles apply to monitoring a patient for recurrence of a disease, such as bladder cancer. The article closes with a theoretical consideration of the circumstances for repeating a test once to check a surprising value.

Open Access Exercise Electrocardiography: A Service to Improve Management of Ischaemic Heart Disease by General Practitioners

An initial study of the use of open access exercise electrocardiography by general practitioners (GPs) in South East Kent showed that patient selection and interpretation of test results was frequently incorrect. After issuing guidelines, modifying the request form and instituting registrar review of all requests, significant improvements in both referral pattern, result interpretation and patient management have resulted.

Forty-nine GPs requested 110 exercise tests during 1988/89. Twelve per cent were not undertaken after discussion with the referring practitioner. Eighty-four per cent of those tested would have been referred to the district general hospital cardiology outpatient department in the absence of open access exercise electrocardiography service. Six per cent of patients were referred directly for invasive investigation. Thirty-five per cent were referred to the district general hospital cardiology outpatient department, whilst 42% were spared hospital referral based on the result of the investigation.

Better use of the modified service was suggested by: Referral of fewer patients with non-cardiac chest pains (P= 0.002); more patients with a moderate pre-test probability of ischaemic heart disease (P<0.05); fewer inappropriate requests (P<0.01); and fewer inappropriately undertaken tests (P< 0.001) than in the previous study. All patients with strongly positive test results were appropriately managed.

Open access exercise electrocardiography in the format investigated is potentially a cost-effective and useful tool to improve diagnosis and management of heart disease bv GPs.