Abstract
1122
Objectives Diastolic dysfunction in hypertrophic cardiomyopathy (HCM) is accompanied by augmented left ventricular (LV) end-diastolic, above all in the presence of LV outflow tract (LVOT) obstruction. Increased backpressure may augment right ventricular (RV) afterload, and induce an oxidative metabolic imbalance between the 2 ventricles. The aim was to study right-to-left ventricular oxidative metabolism in HCM and the effects of alcohol septal ablation (ASA).
Methods Twenty-one HCM patients (age 55±14 years) were enrolled. Eleven healthy subjects (age 48±10 years) served as a control group. Subjects underwent 2D-echocardiography to asses LVOTG, and [11C]acetate PET to determine RVk2 and LVk2, as a non-invasive index of oxidative metabolism. Seven HCM patients with LVOT obstruction, scheduled to undergo ASA, were also studied 6 months after the procedure.
Results RVk2 was higher in HCM patients than controls (0.081±0.021 min-1 vs. 0.061±0.017 min-1, p = 0.05), whereas LVk2 was comparable between groups. Consequently, RVk2/LVk2 was increased in the patients (0.85±0.19 vs. 0.59±0.13, p = 0.004). In patients with obstructive HCM, ASA reduced RVk2 (0.085±0.021 min-1 to 0.072±0.022 min-1, p = 0.001). Inasmuch as LVk2 remained unaffected by the procedure, RVk2/LVk2 was decreased after ASA (0.66±0.18, p = 0.03). The absolute change in LVOTG was related to the absolute change in RVk2 (r = 0.77, p = 0.044).
Conclusions In HCM patients, RV oxygen consumption is increased in relation to the LV. ASA reduces RV oxygen consumption in HCM patients with LVOT obstruction, suggesting that increased LV loading conditions and diastolic dysfunction play a predominant role in augmenting RV workload in these patients