Coronary Hemodynamics in Patients With Severe Aortic Stenosis and Coronary Artery Disease Undergoing Transcatheter Aortic Valve Replacement

Abstract

ObjectivesIn this study, a systematic analysis was conducted of phasic intracoronary pressure and flow velocity in patients with severe aortic stenosis (AS) and coronary artery disease, undergoing transcatheter aortic valve replacement (TAVR), to determine how AS affects: 1) phasic coronary flow; 2) hyperemic coronary flow; and 3) the most common clinically used indices of coronary stenosis severity, instantaneous wave-free ratio and fractional flow reserve.BackgroundA significant proportion of patients with severe aortic stenosis (AS) have concomitant coronary artery disease. The effect of the valve on coronary pressure, flow, and the established invasive clinical indices of stenosis severity have not been studied.MethodsTwenty-eight patients (30 lesions, 50.0% men, mean age 82.1 ± 6.5 years) with severe AS and coronary artery disease were included. Intracoronary pressure and flow assessments were performed at rest and during hyperemia immediately before and after TAVR.ResultsFlow during the wave-free period of diastole did not change post-TAVR (29.78 ± 14.9 cm/s vs. 30.81 ± 19.6 cm/s; p = 0.64). Whole-cycle hyperemic flow increased significantly post-TAVR (33.44 ± 13.4 cm/s pre-TAVR vs. 40.33 ± 17.4 cm/s post-TAVR; p = 0.006); this was secondary to significant increases in systolic hyperemic flow post-TAVR (27.67 ± 12.1 cm/s pre-TAVR vs. 34.15 ± 17.5 cm/s post-TAVR; p = 0.02). Instantaneous wave-free ratio values did not change post-TAVR (0.88 ± 0.09 pre-TAVR vs. 0.88 ± 0.09 post-TAVR; p = 0.73), whereas fractional flow reserve decreased significantly post-TAVR (0.87 ± 0.08 pre-TAVR vs. 0.85 ± 0.09 post-TAVR; p = 0.001).ConclusionsSystolic and hyperemic coronary flow increased significantly post-TAVR; consequently, hyperemic indices that include systole underestimated coronary stenosis severity in patients with severe AS. Flow during the wave-free period of diastole did not change post-TAVR, suggesting that indices calculated during this period are not vulnerable to the confounding effect of the stenotic aortic valve.

Non-hyperaemic pressure ratios to guide percutaneous coronary intervention

“…The feasibility and accuracy of using iFR in patients with severe AS has been demonstrated in several studies. [70][71][72] The data suggest that a lower iFR cut-off (0.82 or 0.83) is better predictive of ischaemia-provoking lesions compared with that validated in patients with no AS. 70 72 This is likely explained by the greater resting blood flow due to the larger myocardial mass and partial microcirculatory vasodilatation which would produce greater transstenotic pressure gradients.…”

“…This was explained by an observed increase in systolic flow following TAVR (thus affecting whole-cycle indices), with no appreciable change in diastolic flow immediately after TAVR and thus no change in iFR. 71 The remainder of the NHPRs have not been assessed in this context. There may be perceivable benefits to diastolic-only rather than whole-cycle indices in this context given the largely variable systolic physiology immediately before and after valve deployment.…”

Determining the Significance of Coronary Plaque Lesions: Physiological Stenosis Severity and Plaque Characteristics

“…Severe aortic stenosis disproportionately impacts the measurement of hyperemic indices in the catheterization lab [94]. Hyperemic indices have been noted to increase significantly following transcatheter aortic valve implantation (TAVI), whereas resting flow (specifically in the wave-free period of diastole) remains unchanged [94]. The improvement in microcirculatory function following TAVI appears to be independent of the severity of concomitant coronary artery disease [94].…”

“…Hyperemic indices have been noted to increase significantly following transcatheter aortic valve implantation (TAVI), whereas resting flow (specifically in the wave-free period of diastole) remains unchanged [94]. The improvement in microcirculatory function following TAVI appears to be independent of the severity of concomitant coronary artery disease [94]. This suggests that, when a patient has both severe AS and CAD, the aortic lesion may be the predominant lesion unless the instantaneous wave-free ratio is ≤0.74.…”

Management of Coronary Artery Disease in the Setting of Transcatheter Aortic Valve Replacement

“…41 This is due to the unequal changes on proximal pressure waveforms caused by stenosed aortic valve, the haemodynamic effect of the uncoupling of aortic valve closure from a decrease in left ventricular pressure, and the effect of left ventricular hypertrophy on microvascular function. 42 However, a recent study by Ahmad et al showed iFR values did not change pre-and post-TAVR (p=0.73), whereas FFR decreased significantly post-TAVR compared with pre-TAVR (p=0.001),indicating iFR may be reliable in identifying significant CAD 43.…”