Cerebral blood flow and neurocognition in patients undergoing TAVR for severe aortic stenosis

Abstract

Aortic valve stenosis (AS) results in higher systolic pressure to overcome resistance from the stenotic valve, leading to heart failure and decline in cardiac output. There has been no assessment of cerebral blood flow (CBF) association with neurocognition in AS, or the effects of valve replacement. The goal was to determine if AS is associated with altered cerebral hemodynamics and impaired neurocognition, and whether transcatheter aortic valve replacement (TAVR) improves hemodynamics and cognition. In 42 patients with planned TAVR, transcranial Doppler (TCD) assessed bilateral MCA mean flow velocity (MFV); abnormality was < 34.45 cm/sec. The neurocognitive battery assessed memory, language, attention, visual-spatial skills, and executive function, yielding a composite Z-score. Impairment was <1.5 SDs below the normative mean. The mean age was 78 years, 59%M, and the mean valve gradient was 46.87mm/Hg. Mean follow-up was 36 days post-TAVR (range 27 - 55). Pre-TAVR, the mean MFV was 42.36 cm/sec (SD=10.17), and the mean cognitive Z-score was -0.22 SD’s (range -1.99 to 1.08) below the normative mean. Among the 34 patients who returned after TAVR, the MFV was 41.59 cm/sec (SD=10.42), not different from baseline (p=0.66, 2.28-3.67). Post-TAVR average Zscores were 0.05 SDs above the normative mean, not meeting the pre-specified threshold for a clinically significant 0.5 SD change. Among patients with severe AS, there was little impairment of MFV on TCD and no correlation with cognition. TAVR did not affect MFV or cognition. Assumptions about diminished CBF and improvement after TAVR were not supported.