Direct assessment of coronary steal and associated changes of collateral hemodynamics in chronic total coronary occlusions.

BACKGROUND: Coronary steal can occur in collateral-dependent myocardium during pharmacologically induced vasodilation. This study assessed coronary steal invasively in chronic total coronary occlusions (TCOs). METHODS AND
RESULTS: In 35 consecutive patients with a percutaneous transluminal coronary angioplasty of a TCO (duration >4 weeks), coronary flow velocity (APV) by a Doppler wire and distal pressure (P(D)) by a pressure wire were assessed in the collateral-dependent vascular bed before dilatation. Indexes of peripheral resistance (R(P)) and for the collateral pathway, including the donor artery segment (R(CP)), were calculated. Changes of these parameters were assessed during intravenous adenosine (140 microg x kg(-1) x min(-1)). Adenosine caused a decrease of APV, ie, coronary steal, in 13 patients (37%; group S), an increase in 11 patients (group R), and no change in 11 patients (group N). Angiographic analysis of collateral pathways showed no difference between the groups, except that in group S all collateral connections were continuously visible but no large collaterals (>0.5 mm) were found. In group N, collaterals were least developed. The increase of APV in group R was associated with a decrease of R(P), whereas R(CP) remained unchanged. In contrast, group S showed no change in R(P) but a significant increase of R(CP), indicating an increased resistance of the donor segment.
CONCLUSIONS: Coronary steal is observed in about one third of TCOs and is associated with specific hemodynamic changes of R(P) and R(CP). Steal occurred only with well-developed angiographically visible collaterals but not with very large collaterals.