Participants will include patients presenting to Kasturba Hospital after obtaining Institutional Ethics Committee approval. Those undergoing CT Coronary Angiography at the discretion of their physician will be screened for eligibility according to predefined inclusion and exclusion criteria.

After obtaining written informed consent, demographic and anthropometric data will be recorded. 

BMI categories for this study are defined as per WHO guidelines.

On CT CAG imaging, two primary parameters will be documented, which are Optimal Chest Compression Point, OCCP, and the Heart Compression Fraction, HCF.
OCCP is identified on the diastolic image showing the maximum compressible areas of both ventricles without the Left Ventricular Outflow Tract being visible.

At the OCCP level, the internal anteroposterior chest diameter and maximum heart AP diameter will be measured to calculate the HCF.

The vertical distance from the xiphisternum’s lower edge to the OCCP will be recorded.

For each participant, the heart anteroposterior diameter will be recorded as the end-diastolic value, while the difference between the internal chest diameter and the proposed Chest Compression Depth will represent the end-systolic value. The Heart Compression Fraction, a modified form of the ejection fraction, will indicate the proportion of the heart compressed at the proposed CCD. Residual depth will be determined by subtracting the proposed CCD from the internal AP chest diameter. Interpretation of values will classify an HCF of 20 percent or more as optimal compression, less than 20 percent as under compression, and a residual depth of less than 2 cm as over compression. The distance between the xiphisternum and the Optimal Chest Compression Point will be used to identify the most effective location for chest compressions. After complete data collection, OCCP and HCF values will be compared across different BMI categories to evaluate their variation with body habitus and to determine the optimal chest compression depth and point for each BMI group. Radiological parameters, including OCCP and HCF, will therefore be comprehensively assessed and analysed across all BMI categories.