Biventricular Pressure-Volume Area Ratio for the Assessment of Left Ventricular Preparedness for Double Switch Operation.

BACKGROUND

Assessing left ventricular (LV) preparedness in congenitally corrected transposition of the great arteries/intact ventricular septum for the double switch operation (DSO) remains challenging. Subpulmonary LV pressure-volume area (PVA)-a ventricular workload metric-compared to systemic right ventricular (RV) PVA, may be a good index of adequacy.

OBJECTIVES

The objectives of the study were to determine if LV-PVA can be estimated (ePVA) from standard parameters and if the LV:RV ePVA ratio is associated with post-DSO outcomes.

METHODS

LV-PVA was measured using conductance catheters and compared to ePVA calculated with simple catheterization and volumetric variables. Agreement and bias were assessed using Pearson correlation and Bland-Altman analysis. In a retrospective cohort, associations between a composite outcome (≥moderate LV dysfunction, transplant, or death) and LV:RV ePVA ratio and clinical variables were evaluated using univariate Cox proportional hazards.

RESULTS

The ePVA showed high agreement and low bias with measured PVA (n = 20). In the retrospective cohort, 6/42 patients (14%, median age at DSO 2.9 years) experienced the composite outcome (median follow-up 1.65 [0.12, 4.58] years). Low LV:RV ePVA and pressure ratios were the only significant associations (HR: 3.9; 95% CI: 1.5-10.0 and HR: 2.4; 95% CI: 1.3-4.2, respectively), whereas LV mass indices were not. Among 8 patients with borderline pressure ratios, 5 with ePVA ratio <0.67 had adverse outcome, whereas 3 with ePVA ratio ≥0.67 did not.

CONCLUSIONS

Estimation of subpulmonary LV-PVA using simple imaging and catheterization data was reliable compared to gold standards. LV:RV ePVA ratio ≥0.67 may serve as a good discriminator for LV preparedness for DSO for congenitally corrected transposition of the great arteries/intact ventricular septum.