The Interaction between Cardiac Sympathetic Tone and Left Ventricular Hypertrophy in Patients with Severe Aortic Stenosis undergoing Trans-catheter Aortic valve Implantation

Aims: To assess cardiac innervation on 123I-metaiodobenzylguanidine (MIBG) imaging in patients with left ventricular hypertrophy (LVH) and aortic stenosis (AS) submitted to transcatheter aortic valve implantation (TAVI) as compared to matched uncomplicated hypertensive patients. Methods: Twenty-two elder (82±5 years) patients with severe AS and severe LVH were recruited. Fourteen matched HT patients with similar degree of LVH and 10 healthy subjects were used as controls. MIBG and 99mTc-tetrofosmin single-photon emission computed-tomography (SPECT) acquisition were obtained to assess sympathetic innervation and LV perfusion. The innervation/perfusion mismatch score was computed, as an indicator of cardiac risk. In TAVI patients the imaging protocol was repeated 6 months after the procedure. Results: Regional MIBG uptake was significantly more inhomogeneous in HT and AS than controls and, therefore, innervation/perfusion mismatch score was higher in both AS (9±8) and HT (5±2) patients than controls (1±1, P<0.001). On multivariate analysis, the presence of severe LVH was an independent predictors of impaired LV sympathetic innervation [OR: 19.45, 95%CI (1.87-201.92); P=0.013]. In patients undergoing TAVI, no differences in measures of LV sympathetic innervation were observed 6 months after the procedure with only a marginal LV mass reduction (-5.4±2.4 g). Conclusions: Cardiac sympathetic innervation is significantly impaired in elder patients with LVH, either with AS or not.