Duration of interventricular septal shift toward the left ventricle is associated with poor clinical outcome in precapillary pulmonary hypertension: A cardiac magnetic resonance study

Background: Right ventricular pressure overload results in interventricular septal shift toward the left ventricle in patients with precapillary pulmonary hypertension (PH). We aimed to investigate the predictive role of the duration of septal curvature configuration during the cardiac cycle, as expressed by the novel marker curvature duration index (CDi) in precapillary PH. Methods: This was a prospective study. All patients underwent cardiac magnetic resonance (CMR). CDi was defined by the number of CMR frames in which septal curvature configuration toward left ventricle is observed *100/total number of frames per cardiac cycle. Time from enrollment to first clinical failure event (death, hospitalization due to PH, and disease progression) was recorded. Results: The study included 36 patients with precapillary PH. During a median follow-up of 20 months (IQR 4-37 months), 14 clinical failure events were observed. Survival ROC analysis showed that the optimal cutoff value of CDi, which predicted clinical failure, was 67%. Kaplan–Meier survival analysis showed that CDi≥67% was associated with a 9.4-fold increase in the risk for clinical failure. Addition of CDi to baseline models including six-minute walk test distance (c-statistic = 0.65 vs. c-statistic = 0.79), NT-proBNP (c-statistic = 0.72 vs. c-statistic = 0.83), and WHO functional class (c-statistic = 0.76 vs. c-statistic = 0.81) improved risk stratification. Conclusion: Ventricular septal shift toward the left ventricle lasting for more than the two thirds of the cardiac cycle is associated with worse prognosis in precapillary PH.