Biventricular Pressure-Volume Loop Analysis Predicts Outcomes After Double Switch Operation For Congenitally Corrected Transposition Of The Great Arteries with Intact Ventricular Septum
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Background
Assessing left ventricular (LV) preparedness in congenitally-corrected transposition of the great arteries/intact ventricular septum (ccTGA/IVS) prior to the double switch operation (DSO) remains challenging. Subpulmonary LV Pressure-Volume Area (PVA) - a comprehensive metric of ventricular workload - when compared to systemic right ventricular (RV) PVA as a benchmark, may be a good index of adequacy.
Aims
Determine (1) if LV PVA can be estimated from simple catheterization and imaging parameters, using conductance-catheter derived PVA as reference, and (2) if LV:RV ePVA ratio predicts outcomes after DSO.
Methods
Subpulmonary LV PVA was measured using conductance catheters and compared to estimated PVA (ePVA) calculated with simple catheterization and volumetric variables. Then, in a retrospective cohort, LV:RV ePVA ratio and other clinical variables were evaluated as predictors for a composite adverse outcome of ≥moderate LV dysfunction, transplant, or death post-DSO.
Results
ePVA yielded high agreement and low bias compared to measured PVA by conductance catheter (n=20). In the retrospective cohort, 6/42 patients (14%) experienced the outcome. Low LV:RV ePVA and pressure ratios were the only significant predictors, while LV mass and mass-to-volume ratio were not. Amongst 8 patients with borderline pressure ratios, ePVA ratio was an excellent discriminator – five with ePVA ratio <0.67 had adverse outcome, whereas three with ePVA ratio ≥0.67 did not.
Conclusions
Estimation of subpulmonary LV PVA using simple imaging and catheterization data was reliable compared to gold standard techniques. LV:RV ePVA ratio ≥0.67 was a strong and novel predictor of LV preparedness for DSO in patients with ccTGA/IVS.
Central Message
Biventricular pressure-volume area (PVA), a surrogate of myocardial V̇O2, can be estimated in ccTGA patients. LV:RV PVA ratio >0.67 is a novel marker of LV preparedness for double switch operation.
Perspective Statement
The current approach for determining LV preparedness prior to double switch operation (DSO) is inadequate with a 15% rate of post-DSO LV dysfunction. Pressure-Volume Area (PVA) is a comprehensive yet concise metric incorporating both pressure and volume work. Use of LV:RV PVA ratio may improve patient selection and therefore outcomes after DSO in patients with ccTGA and intact ventricular septum.
