MR 4D flow-derived left atrial acceleration factor for differentiating advanced left ventricular diastolic dysfunction

Objectives The magnetic resonance (MR) 4D flow imaging-derived left atrial (LA) acceleration factor alpha was recently introduced as a means to non-invasively estimate LA pressure. We aimed to investigate the association of alpha with the severity of left ventricular (LV) diastolic dysfunction using echocardiography as the reference method. Methods Echocardiographic assessment of LV diastolic function and 3-T cardiac MR 4D flow imaging were prospectively performed in 94 subjects (44 male/50 female; mean age, 62 +/- 12 years). LA early diastolic peak outflow velocity (v(E)), systolic peak inflow velocity (v(S)), and early diastolic peak inflow velocity (vD) were evaluated from 4D flow data. alpha was calculated from alpha = v(E) / [(v(S) + v(D)) / 2]. Mean parameter values were compared by t-test; diagnostic performance of alpha in predicting diastolic (dys)function was investigated by receiver operating characteristic curve analysis. Results Mean alpha values were 1.17 +/- 0.14, 1.20 +/- 0.08, 1.33 +/- 0.15, 1.77 +/- 0.18, and 2.79 +/- 0.69 for grade 0 (n = 51), indeterminate (n = 9), grade I (n = 13), grade II (n = 13), and grade III (n = 8) LV diastolic (dys)function, respectively. alpha differed between subjects with non-advanced (grade < II) and advanced (grade >= II) diastolic dysfunction (1.20 +/- 0.15 vs. 2.16 +/- 0.66, p < 0.001). The area under the curve (AUC) for detection of advanced diastolic dysfunction was 0.998 (95% CI: 0.958-1.000), yielding sensitivity of 100% (95% CI: 84-100%) and specificity of 99% (95% CI: 93-100%) at cut-off alpha >= 1.58. The AUC for differentiating grade III diastolic dysfunction was also 0.998 (95% CI: 0.976-1.000) at cut-off alpha >= 2.14. Conclusion The 4D flow-derived LA acceleration factor alpha allows grade II and grade III diastolic dysfunction to be distinguished from non-advanced grades as well as from each other. Clinical relevance statement As a single continuous parameter, the 4D flow-derived LA acceleration factor alpha shows potential to simplify the multi-parametric imaging algorithm for diagnosis of advanced LV diastolic dysfunction, thereby identifying patients at increased risk for cardiovascular events. Key Points Detection of advanced diastolic dysfunction is typically performed using a complex, multi-parametric approach. The 4D flow-derived left atrial acceleration factor alpha alone allows accurate detection of advanced left ventricular diastolic dysfunction. As a single continuous parameter, the left atrial acceleration factor alpha could simplify the diagnosis of advanced diastolic dysfunction.