Reversal of radial artery 'string sign' at 6 months follow-up.

The clinical importance of radial artery string sign is still debated. We present a case of reversal of radial artery string sign in 6 months with concomitant involution of competitive flow arising from an important collateral coronary circulation to an occluded right coronary artery. The hypothesis that the string sign is an extreme form of autoregulation of the radial artery is confirmed, and the flow reserve of this conduit is emphasized.