Cardiac computed tomographic angiography in an outpatient setting: An analysis of clinical outcomes over a 40-month period

Background: Cardiac computed tomographic angiography (CTA) provides for accurate noninvasive diagnosis of coronary artery disease (CAD). Objectives: We analyzed the clinical outcomes over 40 months in patients with and without CAD as determined by CTA in an outpatient setting. Methods: Consecutive symptomatic patients (n = 493; mean age, 58 ± 15 years; 70% men) with an intermediate likelihood of CAD referred for outpatient CTA evaluation were prospectively followed for a mean of 40 ± 9 months. Results: Results of CTA included as normal (defined as normal coronary lumen), found in 32% (157), nonobstructive disease (<50% luminal stenosis) in 41% (204), obstructive disease (≥50% luminal stenosis) in 19% (93). Eight percent (n = 39) had ≥1 major nondiagnostic coronary artery segment. Follow-up identified 21 patients with myocardial infarction (MI) in the significant obstructive CAD and nondiagnostic group. No patients with either normal coronary arteries or nonobstructive disease experienced an MI during follow-up. The 40-month event-free survival was 100% for both the normal and nonobstructive disease groups, 97.5% for the nondiagnostic study group, and 79% for the group with obstructive CAD. After adjustment for age, sex, diabetes mellitus, hypertension, hypercholesterolemia, and baseline coronary artery calcium (CAC), a stepwise multivariable model (Cox regression) showed that obstructive CAD was an independent predictor of cardiac events and had significant incremental value over clinical risk factors and CAC (HR = 16.6; 95% CI, 4.9-55.2; P = 0.0001). Conclusion: In symptomatic patients with an intermediate likelihood of CAD referred for CTA, normal coronary arteries or nonobstructive CAD portends an excellent prognosis. The finding of obstructive CAD identifies patients at higher risk of subsequent MI, independent of cardiovascular risk factors and coronary artery calcium.