Global thickness for accurate and precise evaluation of post-intervention remodelling in left ventricular hypertrophy

Background: Cardiovascular interventions may impact both left ventricular mass (LVM) and end-diastolic volume (EDV), but the net effect on wall thickness has been difficult to accurately evaluate. Global average left ventricular end-diastolic wall thickness (GT) relates non-linearly to LVM and EDV. We hypothesized that if GT is independent of EDV in health, then GT will be an ideal measure of post-intervention change in left ventricular hypertrophy. Methods: GT [mm] was calculated using LVM and EDV by cardiovascular magnetic resonance as previously validated. The correlation between GT and EDV was evaluated in healthy volunteers. Change in GT following intervention was evaluated for aortic stenosis undergoing valve replacement, hypertension commencing antihypertensive medications, athletes undergoing forced detraining, and aortic regurgitation undergoing valve replacement. The performance of GT was compared to LVM/EDV. Results: Among healthy volunteers (n=4461, mean+/-SD age 59+/-10 years, 50% female), EDV correlated with LVM/EDV but negligibly with GT (R2>0.16 vs R2<0.02, p<0.001 for both sexes). GT and not LVM/EDV changed after intervention in all conditions (p≤0.02 for all). Post-intervention changes in GT varied by condition (mean+/-SEM aortic stenosis [n=102]: -1.75+/-0.13mm, hypertension [n=78]: -0.66+/-0.08mm, athletes [n=28]: -0.29+/-0.09mm, aortic regurgitation [n=58]: +0.50+/-0.11 mm, p≤0.02 for all comparisons). Conclusions: In health, GT, unlike LVM/EDV, remains effectively unchanged across EDV values, indicating that GT is a physiological constant in health and can track pathological changes. After intervention, only GT and not LVM/EDV consistently changed. Instead of LVM/EDV, GT should be used to quantify remodelling after interventions in left ventricular hypertrophy.