(CCSP095) INFLUENCE OF ESTIMATED CORONARY CALCIUM FROM SPECT MPI ON INITIATION OF MEDICAL THERAPY

Background: Single photon emission computed tomography myocardial perfusion imaging (SPECT MPI) remains one of the most widely used imaging modalities for the diagnosis and prognostication of coronary artery disease (CAD). Both perfusion abnormalities and coronary artery calcium (CAC) on SPECT MPI are predictive of major adverse cardiovascular outcomes (MACE). Despite the extensive prognostic information provided by SPECT MPI imaging, little is known about how this influences the prescription of medical therapy. Our objective was to determine how visually estimated CAC influence the prescription of aspirin and statins for patients undergoing SPECT MPI.

METHODS AND RESULTS: We performed a retrospective analysis of 7,832 consecutive patients who underwent SPECT MPI testing between 2015 and 2021 with computed tomography attenuation correction imaging. The extent of coronary artery calcium was estimated visually as absent, equivocal, present, or extensive. Normal perfusion was defined as summed stress score < 4. Medication prescriptions were ascertained from a comprehensive provincial database and included prescriptions 180 days before SPECT MPI and within 180 days after. A multivariable logistic regression (adjusting for age, sex, perfusion findings, and medical history) was used to evaluate the association of calcium burden with statin prescriptions.
The prescription of statin after SPECT MPI ranged 35.5% in patients without CAC to 80.6% in patients with extensive CAC, as shown in Figure 1. Prescription rates for aspirin also increased with increasing CAC. Similarly, in patients with normal myocardial perfusion, prescription of statin after SPECT MPI ranged 33.8% in patients without CAC to 78.0% in patients with extensive CAC. In multivariable analyses, the adjusted odds ratio for statin prescription ranged from 1.91 (95% CI 1.33 – 2.74) for equivocal CAC to 3.64 (30.4 – 4.35) for extensive CAC.

Conclusion: Increasing CAC was associated with increased rates of aspirin and statin prescription in patients following SPECT MPI. The increase was seen in patients without perfusion abnormalities and after adjustment for relevant confounders.