Cardiovascular Risk Assessment in Rural Populations: Insights from Epicardial Fat Volume
Harrison Hamblin1, Billy Poulden1, David Hodge1, Johanna Stanton2, Joseph Suttie1
1. The University of Notre Dame Rural Clinical School, Wagga Wagga
2. I-Med Radiology Network, Wagga Wagga
Background:
Cardiovascular and metabolic disease confer a disproportionately high burden of disease in rural and remote communities. Epicardial fat is a visceral fat deposit between the heart and pericardium, implicated in local inflammation and coronary atherosclerosis. Epicardial fat volume (EFV) measurement is a well-established cardiovascular risk assessment tool, but is typically performed using expensive, single-use software and, as a result, has seldom been used in at-risk rural populations.
Aim:
The primary aims of this study were;
- To establish a reliable method for calculating EFV on software available in regional imaging
centres
- To establish the value of EFV in predicting major adverse cardiac events in rural patients
- To analyse the relationship between EFV and traditional cardiovascular risk factors
Methods:
EFV was measured in 50 randomly selected patients from a 2000-patient cohort who underwent routine cardiac CT from 2014 to 2016 at a regional imaging centre in NSW. CT images were obtained using GE Healthcare’s SnapShot Pulse 70 software. Regions of interest were manually traced every five axial slices from the pulmonary artery bifurcation to the cardiac apex with automated interpolation. Fat attenuation thresholds (-30 to -190 HU) were used to highlight the EFV. Inter-rater reliability was assessed in 15 cases and quantified using the intraclass correlation coefficient (ICC), and measurement times were recorded. Patient demographic data, cardiac risk factors and the occurrence of major adverse cardiac events (MACE) after cardiac CT were recorded from hospital records within the Local Health District. MACEs were defined as either acute myocardial infarction, stroke, cardiovascular death or unstable angina. Statistical analyses included chi-squared tests for categorical variables and Mann-Whitney U tests and Spearman correlation coefficients for continuous data.
Results:
Inter-rater reliability was excellent (ICC = 0.986), and the mean EFV measurement time was 181 seconds (range: 122-282). The cohort (mean age: 82.6 years; 34 female) had a mean EFV of 136.5 cm³ (range: 20.9–382.7). Ten (20%) patients experienced a MACE. EFV was lower in the event group (mean 107.3 cm³ vs. 143.8 cm³, p=0.189), though not statistically significant. Higher coronary artery calcium scores were observed in patients with major cardiac events (mean 872.4 vs. 526.9, p=0.163). Male gender and smoking were associated with statistically significantly higher EFV (p<0.001 and p=0.019, respectively).
Conclusion: This study successfully developed a reproducible method for EFV quantification using widely available software in regional imaging centres, demonstrating excellent inter-rater reliability. While EFV was not significantly associated with major adverse cardiac events in this cohort, its relationship with traditional cardiovascular risk factors, particularly male gender and smoking, highlights its potential role in cardiovascular risk stratification. Further research with larger sample sizes is warranted to explore the prognostic value of EFV in rural populations and its integration into routine cardiovascular risk assessment.