The role of calcium score and CT angiography in the medical management of patients with normal myocardial perfusion imaging.

Background: Individuals with normal myocardial perfusion imaging (MPI) may still have substantial coronary artery disease (CAD), which would benefit from aggressive medical therapy. The role of coronary artery calcium-score (CAC) and/or coronary CT Angiography (CTA) to identify additional treatment candidates in this population is unknown.

Methods: Ninety-four patients completed the study protocol and underwent CAC and CTA after MPI.

Results: In 81 patients who had a normal MPI, an algorithm using the clinical predictors, CAC, and then CTA was created to identify candidates for aggressive medical management; 24/81 patients had a high Framingham Risk Score (FRS) or diabetes, and need aggressive medical management, while 6/81 patients had a low FRS and low post-MPI probability of CAD. The use of CAC in 51/81 patients with intermediate clinical predictors would identify 23/51 patients with low risk (CAC < 100) and 11/51 patients (CAC > 400) for aggressive medical management. The remaining 17/51 patients with intermediate CAC scores (100-399) would require CTA, of which, would identify 8/17 additional patients with >50% stenosis for aggressive medical therapy.

Conclusion: A stepwise approach including history, CAC and CTA can identify about 50% of the patients with normal MPI who have a higher risk and may benefit from aggressive medical management.