Relation between the Left Ventricular Mass and the Left Coronary Artery Dimensions as Determined by 16-Channel Multidetector CT: Comparison between the Normotensive group and the Hypertensive Group

Kang, Doo Kyung; Park, Kyung Joo; Tahk, Seung Jea; Kim, Sun Yong

Abstract

PURPOSE
The purpose of this study is to determine the left ventricular mass (LVM) and the left coronary artery dimension and to investigate the relationship between the two values in the normotensive group and hypertensive group with using 16-channel multidetector CT (MDCT).
MATERIALS AND METHODS
Among the patients who underwent a CT coronary angiogram procedure using 16-channel MDCT at Ajou University Hospital from October 2004 to February 2005, 33 patients became the subjects of this study. These 33 patients showed normal findings without calcification or stenosis of the coronary arteries. The total volume of the left ventricular wall was calculated using work-in-progress cardiac CT reconstruction software. The LVM could then be directly calculated by multiplying the left ventricular muscle volume by the myocardial tissue density, which was assumed to be 1.05 g/cm3. The coronary diameter was measured by a fixed threshold method from the transverse reformation images obtained along the long-axis of each coronary artery. We calculated the cross-sectional area (CSA) of the coronary arteries from the equation of pi D2/4 (D=diameter). Regression analysis was performed for the relationship between LVM and the left coronary artery dimensions with using a linear least-squares method. Comparison between the normotensive group and the hypertensive group was done using the Student t test.
RESULTS
The average LVM was 127.9+/-36.2 g (mean+/-standard deviation) and the average left ventricular mass index (LVMI) was 74.7+/-15.5 g in this study population. The average diameter of the coronary arteries was 4.38+/-0.69 mm for the left coronary artery. In all the subjects (n=33, r=0.67, p=0.000) and the normotensive group (n=21, r=0.68, p=0.000), the LVM was significantly correlated with the CSA of the left coronary artery, but not in the hypertensive group (n=12, r=0.57, p=0.062). In the hypertensive group, the CSA of the left coronary arteries per 100 g of muscle mass tended to decrease as the LVM increased. However, no statistical significance was demonstrated (r=-0.51, p=0.087). The end-diastolic left ventricular volume of the hypertensive group was smaller than that of the normotensive group (p=0.039).
CONCLUSION
Using 16-channel MDCT, we could determine the LVM and coronary artery dimensions simultaneously in all the subjects. In all the subjects and the normotensive group, the LVM was significantly correlated with the CSA of the left coronary artery. However, the coronary artery dimensions did not increase commensurately with a concomitant increase of the LVM in the patients with hypertension.