Abstract 10692: Impaired Myocardial Oxygenation Response During Stress in Patients With Severe Aortic Stenosis: Insights From Oxygenation-sensitive Cardiovascular Magnetic Resonance
Background: Left ventricular hypertrophy in aortic stenosis (AS) is characterised by reduced myocardial perfusion reserve due to coronary microvascular dysfunction. However, whether this hypoperfusion leads to myocardial tissue deoxygenation is uncertain. The aim of this study was to assess myocardial oxygenation and perfusion in patients with severe AS but no obstructive coronary artery disease before and after aortic valve replacement (AVR).
Methods and Results: Twenty two patients with isolated severe AS underwent cardiovascular magnetic resonance (CMR) at 3 Tesla. Myocardial function, perfusion (myocardial perfusion reserve index-MPRI) and oxygenation (blood-oxygen level dependent-BOLD signal intensity-SI change) during adenosine stress and rest, and fibrosis (late gadolinium enhancement-LGE) were assessed. No patient had flow limiting coronary stenoses on coronary angiography. Fifteen age- and gender-matched volunteers served as controls. AS patients had reduced perfusion reserve (MPRI 1.0 ± 0.3 vs. controls 1.7 ± 0.3, p < 0.001) and blunted oxygenation response during stress (BOLD SI change 4.8 ± 9.6% vs. controls 18.2 ± 11.6%, p = 0.001). In 10 AS patients scanned 8.0 ± 2.1 months post AVR, MPRI (1.5 ± 0.4, p = 0.005 vs. pre AVR) and BOLD SI change (16.4 ± 7.0%, p = 0.014 vs. pre AVR) improved significantly (Figure 1).
Conclusions: Myocardial perfusion impairment in AS is severe enough to cause a blunted oxygenation response during vasodilator stress. Following AVR, perfusion and oxygenation are restored to near normal levels. These findings suggest that medical treatment strategies that improve perfusion and oxygenation in AS are promising and their effects on prognosis merit testing.
Figure 1. (A) BOLD SI change and (B) MPRI in patients with severe aortic stenosis before and after aortic valve replacement, and in normal controls.
*p<0.05 vs pre AVR and >0.05 vs controls. Error bars indicate ± standard error of mean.
- © 2013 by American Heart Association, Inc.