Abstract 341: Midterm Prognosis of Multislice Computed Tomography Coronary Angiography in Patients With Calcium Scores Zero
Background: A low coronary artery calcium score (CACS) by EBCT, especially CACS zero, is associated with a low rate of incident coronary artery disease (CAD) events. However there are limited data on the relationship between CAD outcomes and MSCT coronary angiography (CTA) in patients with CACS zero.
Objective: To determine the prognostic utility of CTA in patients with CACS zero.
Methods: The study population consisted of consecutive patients who referred for evaluation of suspected CAD. In all patients, CACS were assessed by MSCT using Agaston method prior to CTA. Of 217 patients with CACS zero, 8 patients were excluded because of poor image quality. Thus, 209 patients were included in this study. Obstructive CAD was defined as a ≥75% reduction in diameter in at least one major vessel in CTA. Non-obstructive CAD was defined as a 25–75% reduction. Normal CTA was defined as no coronary plaque. None of these patients had proven CAD. The clinical outcome variables were collected after a minimal interval of 6 months. Cardiac events were defined as cardiac death, nonfatal myocardial infarction, or coronary revascularization.
Results: Follow-up contact was possible for 175 patients (83.7%). The mean follow-up period was 837±516 days. CTA revealed that 16 patients (9.1%) had obstructive CAD, 26 (14.9%) had non-obstructive CAD and 133 (76%) had normal CTA. During follow-up period, a total of 11 cardiac events (6.3%) occurred including nonfatal myocardial infarction in 1 (0.6%) and coronary revascularization in 10 (5.7%). No cardiac death occurred. Of 11 cardiac events, 7 occurred in patients with obstructive CAD and 4 with non-obstructive CAD. Patients with normal CTA had no cardiac event. Sensitivity, specificity, positive and negative predictive values of normal CTA were 100%, 81.1%, 26.2%, 100%, respectively. Kaplan-Meier event-free survival rate was higher in patients with normal CTA as compared to those with abnormal CTA (100% vs. 73.8%, p < 0.0001).
Conclusion: Even in patients with CACS zero, nearly 25% of the study patients had obstructive or non-obstructive CAD. CTA can predict cardiac events successfully in patients referred for evaluation of suspected CAD.