A Novel Concept of the "Standard Human" in the Assessment of Individual Total Heart Size: Lessons from Non-Contrast-Enhanced Cardiac CT Examinations

Abstract

Background: This single-center retrospective observational study reviewed data from 2305 persons examined for coronary artery calcium (CAC) with non-contrast-enhanced cardiac CT. Other cardiac structures, including chamber volumes, were evaluated besides the CAC scoring. We proposed a novel body size indexing measure that may outperform common indices for quantifying total heart volume (THV). Methods: This index is the sum of height and the difference between height (unitless) and body surface area (unitless), [h+(h-BSA)], and if the (h-BSA) equals "zero", it is a feature of the "standard human". Results: We found that, in subjects with a low cardiovascular (CV) risk, the THV normalized for the novel index was simply a function of BW gain, being the highest in obese. If high-CV-risk features (hypertension, diabetes) were present, the measured THV was larger than expected for BW gain, exceeding values observed in low-CV-risk ones. Differences were found to be sex-independent in all BMI categories. Conclusions: Common BSA correction hides these differences and makes the prognostication of CV risk error-introducing. The indexation we proposed might help distinguish the effects of body weight gain from the ones resulting from the presence of certain cardiovascular diseases.

Keywords: coronary artery calcium; standard human; total heart volume.

Figure 1

Multiplane projections of the total heart volume. Abbreviations: BIV—bi-ventricular, IVC—inferior cava vein, LA—left atrium, LAA—left atrial appendage, LV—left ventricle, RA—right atrium, RAA—right atrial appendage, SVC—superior cava vein, RVOT—right ventricular outflow tract.

Figure 2

Relationship between BMI and h-BSA.

Figure 3

Scatterplots of h-BSA difference versus THVh-THVbsa indexed values in the reference subgroup (left) and in the entire group (right) with mean (solid line) and prediction limits (dashed line).

Figure 4

(A) Total heart volume depending on sex and BMI in subjects with low CV risk. (B) Total heart volume depending on sex and BMI in subjects with high CV risk. Abbreviations: F—female, M—male, THV—total heart volume [mL]. Statistics: MANOVA Wilks lambda = 0.99, F = 2.40, p = 0.025, effective hypothesis decomposition. Bars represent the least square means, and vertical bars denote 0.95 confidence intervals. Detailed data are presented in Table 7.