Direct Intracoronary Evidence of Collateral Steal in Humans

Seiler, Christian MD
Fleisch, Martin MD
Meier, Bernhard MD

Received June 5, 1997; revision received August 22, 1997; accepted September 7, 1997.
From Cardiology, University Hospital, Bern, Switzerland.
Correspondence to PD Dr Christian Seller, MD, FESC, University Hospital, Cardiology, Inselspital, Freiburgstr, Bern, Switzerland.
E-mail [email protected].

Circulation 96(12):p 4261-4267, December 16, 1997.

Background Coronary steal is defined as a fall in blood flow toward a certain vascular region in favor of another area during arteriolar vasodilatation, ie, a coronary flow velocity reserve (CFVR) < 1.The purpose of this study was to determine the frequency of steal in patients with a wide range of collateral supply to a vascular area of interest and to assess whether steal is associated with the amount of collateral flow.

Methods and Results One hundred patients 57 +/-9 years old with a coronary artery stenosis to be dilated were examined with intracoronary (IC) Doppler guidewires. IC adenosine-induced CFVR < 1 obtained distal to the stenosis was defined as steal. An index for collateral flow was determined by positioning the Doppler guidewire in the collateral-dependent vessel distal to the stenosis and measuring the flow velocity time integral during (Vi_occl, cm) and after (Vi_o-occl) balloon occlusion. Vi_occl/Vi_o-occl was determined without and with intravenous adenosine (140 [micro sign]g [center dot] kg^-1 [center dot] min^-1). Coronary steal occurred in 10 of 100 patients. Patients with steal showed superior collaterals compared with those without steal: Vi_occl/Vi_o-occl = 0.65 +/- 0.24 in patients with steal versus 0.29 +/- 0.18 in those without steal (P = .0001). In all patients with steal, there was a reduction in collateral flow during intravenous adenosine-induced hyperemia, whereas in the majority (70%) of patients without steal, collateral flow increased or remained unchanged during hyperemia.

Conclusions Coronary steal assessed by intracoronary Doppler flow velocity measurements occurs in 10% of patients with a wide range of coronary collaterals to the vascular area from which blood flow is redistributed.There is a direct association between the presence of steal away from and the amount of collateral flow toward the region under investigation. Collateral flow to the vascular region studied decreases during adenosine-induced hyperemia, which indicates a mechanism of steal via the extensive collaterals. (Circulation. 1997;96:4261-4267.)