Abstract
BackgroundThe integration of computed tomography (CT)-derived left ventricular outflow tract area into the echocardiography-derived continuity equation results in the reclassification of a significant proportion of patients with severe aortic stenosis (AS) into moderate AS based on aortic valve area indexed to body surface area determined by fusion imaging (fusion AVAi). The aim of this study was to evaluate AS severity by a fusion imaging technique in patients with low-gradient AS and to compare the clinical impact of reclassified moderate AS versus severe AS.MethodsWe included 359 consecutive patients who underwent transcatheter aortic valve implantation for low-gradient, severe AS at two academic institutions and created a joint database. The primary endpoint was a composite of all-cause mortality and rehospitalisations for heart failure at 1 year.ResultsOverall, 35% of the population (n = 126) were reclassified to moderate AS [median fusion AVAi 0.70 (interquartile range, IQR 0.65–0.80) cm2/m2] and severe AS was retained as the classification in 65% [median fusion AVAi 0.49 (IQR 0.43–0.54) cm2/m2]. Lower body mass index, higher logistic EuroSCORE and larger aortic dimensions characterised patients reclassified to moderate AS. Overall, 57% of patients had a left ventricular ejection fraction (LVEF) <50%. Clinical outcome was similar in patients with reclassified moderate or severe AS. Among patients reclassified to moderate AS, non-cardiac mortality was higher in those with LVEF <50% than in those with LVEF ≥50% (log-rank p = 0.029).ConclusionsThe integration of CT and transthoracic echocardiography to obtain fusion AVAi led to the reclassification of one third of patients with low-gradient AS to moderate AS. Reclassification did not affect clinical outcome, although patients reclassified to moderate AS with a LVEF <50% had worse outcomes owing to excess non-cardiac mortality.
Highlights
Accurate diagnosis of the severity of aortic valve stenosis (AS) is pivotal to the decision as to whether to proceed with valve replacement therapy and has important prognostic implications [1, 2]
Overall cohort The overall cohort consisted of 359 patients with lowgradient, severe aortic stenosis (AS) on Transthoracic echocardiography (TTE); 57% were men with a median body mass index (BMI) of 26 (24–29) kg/m2 and a median logistic EuroSCORE of 16 (10–24) (Tab. 1)
The main results of the present study can be summarised as follows: (1) 35% of patients who underwent transcatheter aortic valve implantation (TAVI) for severe AS with a low mean gradient (
Summary
Accurate diagnosis of the severity of aortic valve stenosis (AS) is pivotal to the decision as to whether to proceed with valve replacement therapy and has important prognostic implications [1, 2]. The continuity equation to calculate the AVA uses the premise that the left ventricular outflow tract (LVOT) is circular. Multi-slice computed tomography (MSCT) is a threedimensional imaging tool that offers an accurate appreciation of the elliptic morphology and dimensions of the LVOT and aortic annulus [5]. The integration of computed tomography (CT)-derived left ventricular outflow tract area into the echocardiography-derived continuity equation results in the reclassification of a significant proportion of patients with severe aortic stenosis (AS) into moderate AS based on aortic valve area indexed to body surface area determined by fusion imaging (fusion AVAi). The aim of this study was to evaluate AS severity by a fusion imaging technique in patients with low-gradient AS and to compare the clinical impact of reclassified moderate AS versus severe AS.
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