Background As younger patients are being considered for transcatheter aortic valve implantation (TAVI), the assessment and treatment of concomitant coronary artery disease is taking on increased importance. Methods and Results Thirteen contemporary lower‐risk patients with TAVI with severe aortic stenosis (AS) and moderate‐severe coronary lesions were included. Patients underwent assessment of coronary hemodynamics in the presence of severe AS (pre‐ TAVI ), in the absence of severe AS (immediately post‐ TAVI ), and at longer‐term follow‐up (6 months post‐ TAVI ). Fractional flow reserve decreased from 0.85 (0.76–0.88) pre‐ TAVI to 0.79 (0.74–0.83) post‐ TAVI , and then to 0.71 (0.65–0.77) at 6‐month follow‐up ( P <0.001 for all comparisons). Conversely, instantaneous wave‐free ratio was not significantly different: 0.82 (0.80–0.90) pre‐ TAVI , 0.83 (0.77–0.88) post‐ TAVI , and 0.83 (0.73–0.89) at 6 months ( P =0.735). These changes are explained by the underlying coronary flow. Hyperemic whole‐cycle coronary flow (fractional flow reserve flow) increased from 26.36 cm/s (23.82–31.82 cm/s) pre‐ TAVI to 30.78 cm/s (29.70–34.68 cm/s) post‐ TAVI ( P =0.012), to 40.20 cm/s (32.14–50.00 cm/s) at 6‐month follow‐up ( P <0.001 for both comparisons). Resting flow during the wave‐free period of diastole was not significantly different: 25.48 cm/s (21.12–33.65 cm/s) pre‐ TAVI , 24.54 cm/s (20.74–27.88 cm/s) post‐ TAVI , and 25.89 cm/s (22.57–28.96 cm/s) at 6 months ( P =0.500). Conclusions TAVI acutely improves whole‐cycle hyperemic coronary flow, with ongoing sustained improvements at longer‐term follow‐up. This enhanced response to hyperemic stimuli appears to make fractional flow reserve assessment less suitable for patients with severe AS. Conversely, resting diastolic flow is not significantly influenced by the presence of severe AS. Resting indices of coronary stenosis severity, therefore, appear to be more appropriate for this patient population, although large‐scale prospective randomized trials will be required to determine the role of coronary physiology in patients with severe AS.
Background: In patients with stable coronary artery disease, the amount of myocardium subtended by coronary stenoses constitutes a major determinant of prognosis, as well as of the benefit of coronary revascularization. We devised a novel method to estimate partial myocardial mass (PMM; ie, the amount of myocardium subtended by a stenosis) during physiological stenosis interrogation. Subsequently, we validated the index against equivalent PMM values derived from applying the Voronoi algorithm on coronary computed tomography angiography. Methods: Based on the myocardial metabolic demand and blood supply, PMM was calculated as follows: PMM (g)=APV×D 2 ×π/(1.24×10 − 3 ×HR×sBP+1.6), where APV indicates average peak blood flow velocity; D, vessel diameter; HR, heart rate; and sBP, systolic blood pressure. We calculated PMM to 43 coronary vessels (32 patients) interrogated with pressure and Doppler guidewires, and compared it with computed tomography–based PMM. Results: Median PMM was 15.8 g (Q1, Q3: 11.7, 28.4 g) for physiology-based PMM, and 17.0 g (Q1, Q3: 12.5, 25.9 g) for computed tomography–based PMM ( P =0.84). Spearman rank correlation coefficient was 0.916 ( P <0.001), and Passing-Bablok analysis revealed absence of both constant and proportional differences (coefficient A: −0.9; 95% CI, −4.5 to 0.9; and coefficient B, 1.00; 95% CI, 0.91 to 1.25]. Bland-Altman analysis documented a mean bias of 0.5 g (limit of agreement: −9.1 to 10.2 g). Conclusions: Physiology-based calculation of PMM in the catheterization laboratory is feasible and can be accurately performed as part of functional stenosis assessment.
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