Coronary calcium score of zero in stable patients presenting with chest pain or dyspnea: is contrast-enhanced imaging necessary in all cases?
R Dalmau, I Pinilla, E Perez David, S Valbuena, E Arbas, L Fernandez-Gasso, E Refoyo, G Guzman, G Buitrago, E Cuesta, C Labarta, M A Martin Arena, G Acedo, R MorenoAbstract
Introduction
Coronary computed tomography (CT) has become a robust diagnostic tool endorsed by major clinical guidelines for the evaluation of suspected ischemic heart disease, particularly in low- to intermediate-risk patients. The coronary artery calcium (CAC) score (Agatston score) is a validated predictor of cardiovascular risk; it does not require fasting or intravenous contrast administration and is easy to interpret. However, it is not recommended as a standalone test to exclude significant coronary lesions, as the absence of calcified plaque does not rule out the presence of non-calcified plaques. Nevertheless, evidence supports the high negative predictive value of a coronary calcium score of zero.
Purpose
To evaluate the prognostic significance of a CAC score of 0 in patients presenting with chest pain or dyspnea, we analyzed data from a high-volume tertiary center with extensive experience in coronary CT.
Methods
We retrospectively analyzed 391 consecutive coronary CT studies requested for the evaluation of chest pain or dyspnea in stable patients without a prior history of ischemic heart disease. Patients with CAC = 0 were compared with those with CAC > 0 in terms of clinical characteristics and the occurrence of major adverse cardiovascular events (MACE) during follow-up. Categorical variables were analyzed using the chi-square test or Fisher’s exact test, as appropriate. Continuous variables were compared using Student’s t-test or the Mann–Whitney U test. The median follow-up was 73.4 months.
Results
We included 391 consecutive coronary CT studies performed for the evaluation of chest pain or dyspnea in stable patients. The mean age was 66 years, and 65% were women. A CAC score of 0 was documented in 137 patients (35%). Contrast-enhanced imaging was performed in 98% of patients with CAC = 0 and in 72% of those with CAC > 0. Patients with CAC = 0 were younger (56 vs. 70 years) and had a lower burden of cardiovascular risk factors. Only 1.5% of patients with CAC = 0 had significant coronary stenosis (>50%) on angiography, compared with 34% among those with CAC > 0 (p < 0.001). MACE was defined as a composite of cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke. Over a median follow-up of 73.4 months, patients with CAC = 0 had a significantly lower event rate compared with those with CAC > 0 (HR 0.03; 95% CI 0.00–0.27; p < 0.001).
Conclusions
In our experience, a CAC score of 0 in stable patients with chest pain or dyspnea is associated with a low likelihood of significant coronary artery disease and a low rate of major cardiovascular events. Given the high demand for coronary CT in many hospitals, validation of this simplified strategy could help reduce waiting lists and streamline the diagnostic workflow. These findings raise the question of whether contrast-enhanced imaging is necessary in all patients with CAC = 0.Event-free survival according to CACBaseline characteristics according to CAC