Abstract 13145: Ventriculoarterial Coupling Ratio is Associated With Adverse Outcomes in Repaired Tetralogy of Fallot

Abstract

Introduction: Patients with repaired tetralogy of Fallot (TOF) are at risk of premature death and ventricular arrhythmias. The ventriculoarterial coupling (VAC) ratio, the ratio of arterial elastance (Ea) and ventricular end-systolic elastance (Ees), is a measure of cardiac efficiency. Little is known about the VAC ratio in this population. We used a previously described cardiac magnetic resonance (CMR) method to measure right and left VAC ratios in patients with repaired TOF, and assessed the hypothesis that this is related to outcomes. Methods and Results: We measured VAC from CMR data at a single institution on 593 TOF patients (age 21.5 ± 14.4 years) and 58 controls (age 13.2 ± 4.0 years). Frequency matching based on age and gender yielded 326 TOF patients to compare with controls. VAC ratio was calculated for both right (RV) and left (LV) ventricles as Ea/Ees = end-systolic volume/stroke volume. TOF patients had higher RV and LV VAC ratios (p<0.001) (RV results, figure A). Within the TOF cohort, RV VAC ratio correlated positively with LV VAC (r=0.43, p<0.001), but not with pulmonary regurgitation fraction. After a median follow-up of 5.0 (IQR 2.4-8.5) years, 26 patients (4.4%) reached a composite endpoint of death (n=16), aborted sudden cardiac death (n=5), or sustained ventricular tachycardia (VT, n=5). An RV VAC ratio in the highest tertile (T3) was associated with higher risk of the outcome (p<0.001, figure B). Controlling for known risk factors (RV mass-to-volume ratio, atrial arrhythmia and non-sustained VT), an RV VAC ratio ≥1.11 (highest tertile) was independently associated with the composite outcome (hazard ratio 7.3, 95% CI 2.7-19.9, p<0.001). Conclusion: In this cohort, TOF patients demonstrated inefficient VAC as compared with controls. A higher RV VAC ratio was independently associated with the composite outcome of death, aborted sudden cardiac death, or sustained VT. Further investigation of the significance of VAC in this population is warranted.