Influence of percutaneous coronary intervention on coronary microvascular resistance index

Coronary microvascular resistance during maximal hyperemia is generally assumed to be unaffected by percutaneous coronary interventions (PCIs). We assessed a velocity-based index of hyperemic microvascular resistance (h-MR(v)) by using prototypes of a novel, dual-sensor (Doppler velocity and pressure)-equipped guidewire before and after PCI to test this hypothesis. Aortic pressure, flow velocity (h-v), and pressure (h-P(d)) distal to 24 coronary lesions were measured simultaneously during maximal hyperemia induced by intracoronary adenosine. Measurements were obtained in the reference vessel before PCI and in the target vessel before and after PCI, stenting, and ultrasound-guided, upsized stenting. h-P(d) increased from 57.9+/-17.0 to 85.5+/-15.6 mm Hg, and h-MR(v) (ie, h-P(d)/h-v) decreased from 2.74+/-1.40 to 1.58+/-0.61 mm Hg x cm(-1) . s after stenting (both P