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Background: In stable patients without known coronary artery disease (CAD), clinical practice guidelines recommend documentation of ischemia prior to evaluation by invasive angiography. We sought to determine how often non-invasive stress testing is performed in this population and the association between stress test results and obstructive CAD. Methods: Patients undergoing cardiac catheterization for exclusion of CAD who were without prior history of myocardial infarction, PCI, or CABG were identified from 601 hospitals using the American College of Cardiology National Cardiovascular Data Registry between 2005 – 2007. Significant obstructive CAD was defined as the presence of any stenosis ≥ 50% left main or ≥ 70% major epicardial vessel. Patient demographics, risk factors, symptoms, stress test status and CAD presence were determined. Results: A total of 376,430 patients without known CAD were identified. The median age was 61 years, 53% were male, 26% had diabetes, and 69% had hypertension. At angiography, 142,912 (38%) of patients were found to have significant obstructive CAD. Symptom status was associated with the presence of CAD (stable angina 50%, atypical 25%, asymptomatic 40%; p<0.001). Stress testing was performed in 316,248 (84%) of patients prior to angiography, and results were associated with the presence of CAD (p<0.001) see Table . Although a positive stress test was noted in 255,617 (68% of patients undergoing cath), obstructive CAD was noted in only 105,435, yielding a positive predictive value of 41%. Conclusions: In a large national registry of stable patients without known CAD undergoing invasive angiography, only 38% were found to have significant obstructive disease. Although performed in 84% of patients prior to cath, the low positive predictive value of current stress tests may have contributed to the high rate of patients without obstructive CAD. Table p value for stress test results and presence of obstructive CAD p<0.001
Patel et al. (Tue,) studied this question.