Abstract 19208: Higher Cornell Product and QTc on Exercise Stress Testing are Correlated with Lower Cardiac MRI T1 Times in Hypertrophic Cardiomyopathy

Abstract

Hypertrophic cardiomyopathy (HCM) is characterized by ventricular hypertrophy, myocyte disarray and interstitial fibrosis which result in arrhythmias, sudden death and heart failure. Studies have shown that the resting EKG can be used to predict abnormalities on contrast enhanced cardiac MRIs. However, studies correlating changes seen in the EKG during exercise and measurements on MRIs in the HCM population have not been studied. The exercise state is clinically relevant for patients with HCM and exercise stress testing is an economical tool that is often abnormal in HCM patients. We assessed the hypothesis that during the exercise state changes in various EKG parameters such as the Cornell product, for example, would correlate with lower T1 times on contrast enhanced MRIs. One hundred and sixty three patients (67% male) were evaluated fulfilling standard HCM criteria and clinical history was obtained. EKGs from Bruce protocol treadmill stress testing were independently analyzed for heart rate, QRS duration, LVH criteria including Sokolow-Lyon and Cornell product, ST changes, T wave inversions, and strain pattern. Contrast enhanced MRIs were performed and T1 mapping was analyzed independently. As shown in Table 1, compared to the rest state, peak exercise EKGs showed higher Cornell product, QTc, QRS duration, greater presence of strain pattern, and non-specific ST depressions and T wave inversions (p < 0.001 in all groups). The Cornell product (r = -0.71 for rest, r = -0.86 for exercise state) and QTc (r = -0.62 for rest, r = -0.74 for exercise) were correlated with lower T1 times. In conclusion, the novel findings of this study are that abnormalities in parameters such as the Cornell product or QTc correlate with lower T1 times on MRI, especially in the exercise state. Lower T1 times are associated with greater fibrosis and abnormalities in repolarization or conduction (as seen in EKGs during the exercise state) could indicate a subpopulation of HCM patients at greater risk.