Abstract 1103: Coronary Artery Calcium and Cardiopulmonary Exercise Testing: A New Method to Diagnose Coronary Artery Disease in Asymptomatic Subjects and to Refer to Coronary Angiography
Coronary artery calcium (CAC) is the most accurate method for early detection of coronary atherosclerosis. However, CAC has low specificity for symptomatic coronary artery disease (CAD), because calcification implies atherosclerosis but not necessarily the presence of a stenosis. The combination of anatomical information and functional assessment should be more accurate for diagnosing CAD than any single non-invasive test and may help clinicians to interpret if an atherosclerotic lesion is responsible of myocardial ischemia (MI) or not. We tested the combination of CAC with cardiopulmonary exercise test (CPET) in a group of subjects free of CV disease to detect or exclude inducible MI and CAD. CPET has been recently shown to improve both sensitivity (+89%) and specificity(+15%) of traditional ECG stress test through the analysis of VO2 kinetics that reflects stroke volume and cardiac output during exercise. We prospectively studied 570 subjects between 35 and 70 years with no history of CV disease. The most frequent CV risk factor was family history (56%), followed by hypertension (38%), cigarette smoking (22%) and hypercholesterolemia (21%). The SCORE was 2.4(2.1), range 0 –11. All patients underwent a CPET on a cycle ergometer and CAC by MDCT. CPET was positive in 108 subjects and negative in 462. Follow up lasted 36(6) months. Of 108 subjects with a positive CPET, CAC was present in 86(79.6%). Coronary angiography was performed in 108 subjects and revealed at least one significant stenosis in 86 subjects. Of them, 4 patients had coronary artery bypass surgery and 6 PTCA/stenting. Of 462 subjects with a negative CPET, CAC was present in 211 (45.6%) with an Agatson score of 1–99 in 25.7%, 100 –399 in 9.6%, 400 – 800 in 7.6% and >800 in 3.3%. No one of these subjects had coronary events during the follow-up. In conclusion, the combination of CPET+CAC identifies subjects with silent coronary artery disease and refers those with inducible ischemia to coronary angiography with a specificity of 100%. If we used ECG stress test instead of CPET both sensitivity and specificity of the model was significantly lower (64% and 72%, respectively, P<0.001).