CT coronary angiography and exercise ECG in a population with chest pain and low-to-intermediate pre-test likelihood of coronary artery disease
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Objective: To evaluate diagnostic accuracy of exercise ECG (ex-ECG) versus 64-slice CT coronary angiography (CT-CA) for the detection of significant coronary artery stenosis in a population with low-to-intermediate pre-test likelihood of coronary artery disease (CAD). Design: Retrospective single centre. Setting: Tertiary academic hospital. Patients: 177 consecutive patients (88 men, 89 women, mean age 53.5±7.6 years) with chest pain and low-to-intermediate pre-test likelihood of CAD were retrospectively enrolled. Interventions: All patients underwent ex-ECG, CT-CA and invasive coronary angiography (ICA). Main outcome measure: A lumen diameter reduction of ≥50% was considered as significant stenosis for CT-CA. Ex-ECG was classified as positive, negative or non-diagnostic. Results were compared with ICA. Diagnostic accuracy of CT-CA and ex-ECG was calculated using ICA as the reference standard. A parallel comparative analysis using a cut-off value of 70% for significant lumen reduction was also performed too. Results: ICA disclosed an absence of significant stenosis (≥50% luminal narrowing) in 85.3% (151/177) patients, single-vessel disease in 9.0% (16/177) patients and multivessel disease in 5.6% (10/177) patients. Prevalence of obstructive disease at ICA was 14.7% (26/177). Sensitivity, specificity, positive and negative predictive values at the patient level were 100.0%, 98.7%, 92.9%, 100%, respectively, for CT-CA and 46.2%, 16.6%, 8.7%, 64.1%, respectively, for ex-ECG. Agreement between CT-CA and ex-ECG was 20.9%. CT-CA performed equally well in men and women, while ex-ECG had a better performance in men. After considering the cut-off value of 70% for significant stenosis, the difference between CT-CA and ex-ECG remained significant (p<0.01), with a low agreement (21.5%). Conclusions: CT-CA provides optimal diagnostic performance in patients with atypical chest pain and low-to-intermediate risk of CAD. Ex-ECG has poor diagnostic accuracy in this population. Concerns are related to risk of radiation dose versus the benefits of correct disease stratification.