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Use of electron beam tomography data to develop models for prediction of hard coronary events
P Raggi1, B Cooil, T Q Callister
1Preventive Cardiology and Non-Invasive Imaging, Tulane University School of Medicine, 1430 Tulane Ave., New Orleans, LA 70112, USA. praggi@tulane.edu
Insights
Coronary artery calcification (CAC) scoring using electron beam tomography (EBT) improves prediction of cardiac events. An age- and sex-specific calcium score (CS%) is the best predictor, offering valuable prognostic information beyond traditional risk factors.
Area of Science:
- Cardiology
- Medical Imaging
- Preventive Medicine
Background:
- Predicting hard cardiac events like myocardial infarction and coronary death is challenging.
- Traditional risk factors for coronary artery disease (CAD) have limitations in risk stratification.
- Novel risk indicators are needed to enhance predictive accuracy for CAD events.
Purpose of the Study:
- To evaluate the predictive value of coronary artery calcification (CAC) measures for hard cardiac events.
- To develop and assess prediction models for hard cardiac events using CAC alone and with traditional risk factors.
- To determine if CAC measures provide incremental prognostic information beyond established CAD risk factors.
Main Methods:
- Electron beam tomography (EBT) was used to measure CAC in two groups of asymptomatic patients.
- Group A (n=676) was prospectively followed for hard cardiac events.
- Group B (n=10,122) served as controls for calculating calcium score nomograms.
Main Results:
- Univariate analysis identified age, smoking, diabetes, CAC presence, and calcium score metrics (absolute CS, CS%) as predictors of hard events.
- Multiple logistic regression revealed that age- and sex-specific CS% was the sole significant predictor.
- CS% provided incremental prognostic value when added to traditional risk factors, significantly improving prediction models (AUC 0.84 vs 0.71).
Conclusions:
- Age- and sex-specific calcium score (CS%) is a superior predictor of hard coronary events compared to traditional risk factors alone.
- EBT-derived CAC scoring, particularly CS%, offers significant incremental prognostic information for CAD risk assessment.
- CAC scoring should be considered for risk stratification in asymptomatic individuals, complementing conventional risk factor evaluation.
Background:
Prediction of hard cardiac events (myocardial infarction and coronary death) remains difficult in spite of the identification of several relevant risk factors for the development of coronary artery disease (CAD). New indicators of risk might add to our predictive ability. We used measures of coronary artery calcification (CAC) found by electron beam tomography (EBT) imaging to develop prediction models for hard cardiac events alone and in association with traditional risk factors for CAD.
Methods:
Two groups of patients were studied: group A, 676 asymptomatic patients (mean age 52 years, 51% men) prospectively followed up for 32 +/- 7 months after being referred by primary care physicians for a screening EBT, and group B, 10,122 asymptomatic patients screened by EBT at one center and used as controls for calculation of calcium score nomograms.
Results:
The occurrence of hard events in group A patients was related to traditional risk factors for CAD, presence of CAC (score >0), Ln (1 + absolute calcium score [CS]), and age- and sex-specific CS percentiles (CS%). Univariate analyses showed that age, smoking, diabetes mellitus, presence of CAC, Ln (1 + absolute CS), and CS% were predictive of hard events (all P <.05). Multiple logistic regression analyses demonstrated that CS% was the only significant predictor of events and provided incremental prognostic value when added to traditional risk factors for CAD (chi-square, P <.001). In a comparison of receiver-operator characteristic curves for prediction of hard events, the area under the curve for CS% plus conventional risk factors and age was significantly larger than that obtained by use of traditional risk factors and age separately as predictors (0.84 vs 0.71, respectively, P <.001). Furthermore, the area under the curve of CS% alone was significantly larger than that of traditional risk factors and age combined (0.82 vs 0.71, P =.028).
Conclusions:
Patients are usually selected for EBT screening on the basis of the presence of conventional risk factors for CAD. However, an age- and sex-specific calcium score provides the best predictive model for the occurrence of hard coronary events and adds incremental prognostic information to conventional risk factors for CAD.