Abstract 10875: Impaired Stress Myocardial Oxygenation and Not Perfusion Reserve is Associated With Arrhythmic Risk in Hypertrophic Cardiomyopathy: Insights From a Novel Oxygen Sensitive Cardiac Magnetic Resonance Approach

In hypertrophic cardiomyopathy (HCM), myocardial ischemia may promote life-threatening ventricular arrhythmias. Blood oxygen level dependent cardiac magnetic resonance (BOLD CMR) detects blunted stress oxygenation in HCM despite normal perfusion. Whether or not stress oxygenation or myocardial perfusion reserve (MPRI) on CMR determines arrhythmic risk is unknown. In practice, T2-prepared steady-state free precession (T2p-SSFP) BOLD suffers from reduced precision due to heart rate dependence, coil sensitivity and off-resonance effects. To resolve this, we identified a novel oxygen-sensitive CMR approach called Fast Low Angle Shot normalized T2p-SSFP BOLD (nBOLD). A comparison of standard (sBOLD) and novel approaches in 20 healthy subjects confirmed that nBOLD is more precise than sBOLD (Fig1A). Furthermore, with this novel approach, oxygen-sensitive signal could be visualized. We then tested the hypothesis that stress oxygenation (nBOLD) is more predictive of arrhythmic risks than MPRI in HCM. 103 genotyped-HCM and 32 matched healthy subjects underwent adenosine stress BOLD, perfusion and late gadolinium (LGE) CMR. HCM patients were monitored for ventricular tachycardia on 24-hour Holter. Stress oxygenation and MPRI were impaired in HCM. Stress oxygenation was more blunted in sarcomeric HCM than genotype negative HCM (Fig1C,D). Stress oxygenation, but not MPRI, was associated with ventricular tachycardia on univariate analysis. A stepwise increase in ventricular tachycardia prevalence was seen with decreasing quartiles of oxygenation (Fig1E). HCM patients with the lowest quartile of oxygenation had a three-fold increased risk of ventricular tachycardia (OR 3.04, p=0.04) after adjusting for LGE mass, age and sudden cardiac death risk. In conclusion, we have successfully discovered and implemented a novel oxygen-sensitive CMR approach, providing insights into the role of stress oxygenation as a promising biomarker of arrhythmic risk in HCM.