Visually assessed coronary and cardiac calcium outperforms perfusion data during scintigraphy in the prediction of adverse outcomes.

OBJECTIVES

To determine whether calcifications of the coronary arteries (coronary artery calcium 0 to 4 score), or extending the assessment also to cardiac valves and thoracic aorta (overall calcium 0 to 8 score), as seen on computed tomography for attenuation correction during stress-scintigraphy (SPECT-CT), are associated with total mortality and non-fatal myocardial infarction. We aimed to assess whether these calcifications added to the prognostic value of SPECT imaging.

BACKGROUND

The presence/amount of calcium in the coronary arteries, but also in the heart valves and aorta, has been associated with cardiovascular (CV) and all-cause mortality. This information can be obtained during SPECT-CT examinations, where low resolution CT images are co-registered for attenuation correction of myocardial perfusion, but then discarded.

METHODS

Clinical data were collected on 353 consecutive patients submitted to stress SPECT-CT between Sept 2010 and Oct 2012, for suspected coronary artery disease (CAD). Follow-up data on outcomes were collected retrospectively.

RESULTS

Mean age was 72 and 58% were male. Mean follow-up was 6.4 years, during which 48 subjects died (15 from CV causes) and 10 had non-fatal myocardial infarction (MI). Reversible perfusion defects were detected in 55 patients (15.6%), 39 of whom (11%) had >mild defects. The presence of a calcium score > 1 in the attenuation correction images was the strongest univariate predictor of all-cause death or MI (hazard ratio 7.21, p < .001). On multivariate analysis, controlling for age, gender and myocardial perfusion defects an overall calcium score > 2 remained a predictor of all-cause death or non-fatal MI (hazard ratio 4.12, p < .001).

CONCLUSIONS

Visual assessment of coronary or overall coronary, cardiac and aortic calcium in the CT images used for attenuation correction during SPECT-CT is feasible and reproducible. It was strongly associated with all-cause death and MI, even after controlling for clinical variables and myocardial perfusion data. This simple visual calcium assessment does not add additional costs or radiation, and may significantly improve risk-assessment of patients with suspected CAD undergoing SPECT-CT.

CONDENSED ABSTRACT

Calcium in the coronary arteries, heart valves and aorta has been associated with worse prognosis. We sought to determine whether assessment of such calcifications on computed tomography images (co-registered for myocardial perfusion attenuation correction and then discarded) are independently associated with long-term outcome on top of available data. We enrolled 353 consecutive patients, referred for suspected coronary artery disease. An overall calcium score > 1 in the attenuation correction images was the strongest univariate (hazard ratio 7.21, p < .001) and multivariate predictor of all-cause death or non-fatal MI (hazard ratio 4.12, p < .001), even after controlling for clinical variables and myocardial perfusion data.