MP-453088-9 THE SPATIAL VENTRICULAR GRADIENT IS ASSOCIATED WITH CARDIAC MAGNETIC RESONANCE MARKERS OF OF DIFFUSE MYOCARDIAL FIBROSIS

Abstract

Cardiac MRI (CMR) markers of diffuse myocardial fibrosis are of prognostic importance in cardiomyopathies. However, CMR is expensive, time-consuming, and not readily available. An ECG correlate for diffuse fibrosis, via its effect on myocardial electrical heterogeneity, would be useful. The spatial ventricular gradient (SVG), a vectorcardiographic (VCG) measurement of myocardial electrical heterogeneity, is a promising ECG correlate of CMR detected diffuse fibrosis. To assess the relationship of the SVG to extracellular volume (ECV) and native T1 values in patients referred for CMR. Retrospective cohort study of all patients referred for CMR from 2015 to 2022 at a single academic medical center who had ECG(s) performed within 30 days of CMR. Median VCGs were constructed from the 12-lead ECGs, and SVG was calculated as the area under the X, Y, and Z median beats. ECV and native T1 values were regressed on SVG vector magnitude, QT interval, and QRS duration using linear regression. Median values were compared using the rank-sum test. We evaluated 679 patients who underwent CMR and had ECV and T1 measurements and a recent ECG. The sample was 60% male and the mean age was 55 +/- 16 years. The figure shows how SVG vector magnitude was inversely correlated with both T1 and ECV (p<0.001 for both). In the lowest and highest quartiles of both ECV (0.03-0.28 vs 0.35-0.68) and T1 (1041-1227 vs 1315-1535 ms), the median SVG magnitude was significantly lower: 48.7 vs 32.3 mv*ms for ECV, and 48.5 vs 30 mv*ms for T1 (p<0.001 for both). In a multivariable model, the SVG remained independently associated with ECV and T1 after adjustment for QT interval, QRS duration, age, and sex (p<0.001). SVG magnitude is independently associated with CMR measures of extracellular fibrosis. Patients with higher SVG magnitude are unlikely to have a significant burden of diffuse fibrosis.