Introduction: Aortic stenosis (AS) causes angina despite unobstructed arteries.Measurement of conventional coronary hemodynamic parameters in patients undergoing valvular surgery has failed to explain these symptoms.With the advent ofpercutaneous aortic valve replacement (PAVR) and developments in coronary pulse wave analysis it is now possible to instantaneously abolish the valvular stenosis and measure resulting changes in waves which direct coronary flow.Methods: Intracoronary pressure and flow velocity were measured immediately before and after PAVR in six patients with unobstructed coronary arteries.Using coronary pulse wave analysis, we calculated the intra-coronary diastolic suction wave (the principal accelerator of coronary blood flow).To test physiological reserve to increased myocardial demand, we measured at rest and during pacing at 90 and 120 beats per minute.Results: Prior to PAVR the basal myocardial suction wave intensity was 2.2 ±1 x1 0-5 Wm-2s-2, and this increased in magnitude with increasing severity of aortic stenosis (r=0.82, p=0.04).This wave decreased markedly with increasing heart rate (β coefficient =-0.19 x10-4 Wm-2s-2, p=0.003).After PAVR despite a fall in basal suction wave (2.2 ±1 v 1.0 ±0.4x 10-5 Wm-2s-2, p<0.004), there was an immediate improvement in coronary physiological reserve with increasing rate (β3 coefficient =0.12 x 10-4 Wm-2s-2, p=0.014).Conclusions: In aortic stenosis, the coronary physiological reserve is reversed: instead of increasing when heart rate rises, the coronary diastolic suction wave paradoxically decreases.Immediately after PAVR, this physiological reserve returns to a normal positive pattern.This may explain how aortic stenosis can mimic coronary angina and the prompt relief after PAVR.