The subject guide catheter extension/pre-dilatation system includes an outer delivery sheath, an inner member extending within the sheath, and a mechanism for engagement/disengagement of the inner member to/from the sheath. The inner member is configured with a tapered distal tip having a delivery micro-catheter and a pre-dilatation balloon member attached to the tapered distal tip. The guidewire and a guide catheter are advanced to the vicinity of the treatment site within a blood vessel. Subsequently, the inner member and outer delivery sheath, in their engaged configuration, are advanced along the guidewire inside the guide catheter towards the site of treatment. At the treatment site, the balloon member is inflated for pre-dilatation treatment. The inner member is disengaged and retracted from the outer delivery sheath, and a stent is delivered to the treatment site.
