True-severe aortic stenosis had significantly smaller myocardial flow reserve compared to pseudo-severe aortic stenosis (1.19 vs 1.76, p=0.003), with MFR <1.8 providing 85% accuracy for distinction.
Observational (n=50)
Yes
Does myocardial flow reserve measured by PET perfusion imaging differentiate true-severe from pseudo-severe low-flow, low-gradient aortic stenosis?
Myocardial flow reserve measured by PET is significantly more impaired in true-severe compared to pseudo-severe low-flow, low-gradient aortic stenosis, offering a potential diagnostic tool to distinguish the two.
Absolute Event Rate: 1.19% vs 1.76%
p-value: p=0.003
BACKGROUND: Impairment of myocardial flow reserve (MFR) in aortic stenosis (AS) with normal left ventricular function relates to the haemodynamic severity. OBJECTIVES: To investigate whether myocardial blood flow (MBF) and MFR differ in low-flow, low-gradient AS depending on whether there is underlying true-severe AS (TSAS) or pseudo-severe AS (PSAS). METHODS: In 36 patients with low-flow, low-gradient AS, dynamic 13Nammonia PET perfusion imaging was performed at rest (n = 36) and during dipyridamole stress (n = 20) to quantify MBF and MFR. Dobutamine echocardiography was used to classify patients as TSAS (n = 18) or PSAS (n = 18) based on the indexed projected effective orifice area (EOA) at a normal flow rate of 250 ml/s (EOAI(proj )0.55 cm(2)/m(2)). RESULTS: Compared with healthy controls (n = 14), patients with low-flow, low-gradient AS had higher resting mean (SD) MBF (0.83 (0.21) vs 0.69 (0.09) ml/min/g, p = 0.001), reduced hyperaemic MBF (1.16 (0.31) vs 2.71 (0.50) ml/min/g, p<0.001) and impaired MFR (1.44 (0.44) vs 4.00 (0.91), p<0.001). Resting MBF and MFR correlated with indices of AS severity in low-flow, low-gradient AS with the strongest relationship observed for EOAI(proj) (r(s) = -0.50, p = 0.002 and r(s) = 0.61, p = 0.004, respectively). Compared with PSAS, TSAS had a trend to a higher resting MBF (0.90 (0.19) vs 0.77 (0.21) ml/min/g, p = 0.06), similar hyperaemic MBF (1.16 (0.31) vs 1.17 (0.32) ml/min/g, p = NS), but a significantly smaller MFR (1.19 (0.26) vs 1.76 (0.41), p = 0.003). An MFR <1.8 had an accuracy of 85% for distinguishing TSAS from PSAS. CONCLUSIONS: Low-flow, low-gradient AS is characterised by higher resting MBF and reduced MFR that relates to the AS severity. The degree of MFR impairment differs between TSAS and PSAS and may be of value for distinguishing these entities.
Burwash et al. (Tue,) conducted a observational in Low-flow, low-gradient aortic stenosis (n=50). True-severe aortic stenosis vs. Pseudo-severe aortic stenosis was evaluated on Myocardial flow reserve (MFR) (p=0.003). True-severe aortic stenosis had significantly smaller myocardial flow reserve compared to pseudo-severe aortic stenosis (1.19 vs 1.76, p=0.003), with MFR <1.8 providing 85% accuracy for distinction.
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