A Study of the Cypher Sirolimus-Eluting Stent to Treat Bifurcation Lesions.

Inclusion Criteria: 1. Has a diagnosis of angina pectoris as defined by Canadian Cardiovascular Society Classification (CCS I, II, III, IV) OR unstable angina pectoris (Braunwald Classification B\&C, I-II) OR has documented silent ischemia; 2. Involves a single treatment of a de novo bifurcation lesion in native coronary arteries of patients with single or multivessel disease; patients with multiple lesions can be included only if other lesions treated during the index procedure are successfully treated prior to the treatment of the bifurcation lesion; 3. Has a true bifurcation lesion defined as stenosis \> 50% in both the main branch and the ostium of the side branch; 4. Has a main branch vessel that is \<=2.5 mm and \<=3.5 mm in diameter by on-line QCA proximal to the bifurcation; 5. Has a side branch vessel that is \<=2.5 mm and \<=3.5 mm in diameter by on-line QCA. Exclusion Criteria: 1. Patient has experienced a Q-wave or non-Q-wave myocardial infarction with documented elevation of CK levels \> 2 times normal or CK-MB levels \> 3 times normal within the preceding 24 hours and/or the CK and CK-MB enzymes remain above normal at the time of treatment; 2. Has unstable angina classified as Braunwald A I-III, or III B or C, or is having a peri infarction; 3. Has a bifurcation lesion in a non protected left main; 4. Has an ejection fraction \<=35%; 5. There is presence of thrombus in the bifurcation lesion; 6. Has a totally occluded vessel.