Long-term prognosis of coronary artery calcium scoring on top of cardiac SPECT in stable symptomatic patients.

Background

The coronary artery calcium score (CACS) has strong prognostic value in stable chest pain patients. However, studies with follow-up beyond 5 years are scarce. We studied the long-term prognosis of CACS beyond pre-test probability (PTP) and single-photon emission computed tomography (SPECT) results for major adverse cardiac events (MACE).

Methods

We performed a retrospective cohort study among 6059 patients with non-acute chest pain, suspected of obstructive coronary artery disease who underwent clinically indicated SPECT/CT imaging with simultaneous CACS. Data on MACE, defined as cardiac death and non-fatal myocardial infarction, were collected during follow-up. The value of CACS in addition to PTP categories and SPECT results was studied using multivariable Cox analysis.

Results

During a median follow-up of 9.1 years (IQR 7.8-10.4), 6.1% (N = 365) of patients suffered from MACE. In CACS 0 (27% of all) annual MACE rates were 0.2-0.3% across PTP categories, and 0.2-0.6% across SPECT results. In CACS >1000 (10 % of all) annual MACE rates were 2.5-2.5% across PTP categories and 2.2-3.0% across SPECT results. High CACS (>1000 vs. 0, HR 4.14; 95%CI, 2.64-6.53) and abnormal SPECT (>10% ischemia vs. normal, HR 1.78; 95%CI, 1.27-2.46) predicted MACE. Compared to a model of PTP and cardiovascular risk factors (area under the ROC curve 0.72), adding SPECT improved discriminatory ability (0.73; p = 0.003), and adding CACS on top of SPECT improved performance further (0.75; p < 0.001).

Conclusions

CACS adds incremental prognostic information to PTP and SPECT in stable chest pain patients. Absence of coronary calcium results in an excellent long-term prognosis regardless of PTP and SPECT result.