Noninvasive Leg-Positive Pressure Stress Echocardiography Reveals Preload Reserve in Adult Patients after Complete Repair of Tetralogy of Fallot

Abstract

Long-term sequelae such as right ventricular dysfunction and reduced hemodynamic reserve are the main determinants of cardiovascular outcomes after repair of tetralogy of Fallot (TOF). Echocardiographic parameters at rest offer only partial information on impaired hemodynamics in these patients, and data during stress testing are lacking. The leg-positive pressure (LPP) maneuver has recently been reported to be able to apply acute preload stress. The aim of this study was to test the hypothesis that preload reserve is impaired and ventricular interaction is exacerbated in patients with TOF. In this prospective cross-sectional study, we recruited 44 consecutive patients with TOF and 30 normal control subjects. Echocardiography was performed both at rest and during LPP stress, and preload reserve was defined as the change between baseline stroke volume (SV) and that obtained during LPP stress. The eccentricity index was calculated as the ratio of the left ventricular anteroposterior to septal-lateral dimensions to quantify ventricular interaction. LPP stress significantly increased SV from 73±14 to 83±16mL(P<.01) in control subjects, while the increase in SV was significantly blunted (from 75±19 to 79±18mL; P<.01 for interaction) in patients with TOF. The eccentricity index significantly changed during LPP stress in patients with TOF only from 1.07±0.13 to 1.13±0.14 (P<.01 for interaction). Patients with TOF were subdivided into two subgroups on the basis of the median value of increased response in SV (22 with sufficient and 22 with insufficient preload reserve). Multivariate analysis identified significant pulmonary regurgitation as the only independent determinant factor for insufficient preload reserve (odds ratio, 4.57; 95% CI, 1.048-19.90; P=.04). In patients after repair of TOF, ventricular interaction was exacerbated and preload reserve was impaired, especially in patients with significant pulmonary regurgitation. LPP stress testing may direct tailored treatment approaches, risk stratification, and clinical decision-making, such as more aggressive pharmacologic therapy, meticulous outpatient follow-up, or earlier reintervention.